Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

9 files changed, 5223 insertions, 0 deletions

diff --git a/third_party/rust/askama_derive/src/config.rs b/third_party/rust/askama_derive/src/config.rs
new file mode 100644
index 0000000000..cf22a720f0
--- /dev/null
+++ b/third_party/rust/askama_derive/src/config.rs
@@ -0,0 +1,582 @@
+use std::collections::{BTreeMap, HashSet};
+use std::convert::TryFrom;
+use std::path::{Path, PathBuf};
+use std::{env, fs};
+
+#[cfg(feature = "serde")]
+use serde::Deserialize;
+
+use crate::CompileError;
+
+#[derive(Debug)]
+pub(crate) struct Config<'a> {
+    pub(crate) dirs: Vec<PathBuf>,
+    pub(crate) syntaxes: BTreeMap<String, Syntax<'a>>,
+    pub(crate) default_syntax: &'a str,
+    pub(crate) escapers: Vec<(HashSet<String>, String)>,
+    pub(crate) whitespace: WhitespaceHandling,
+}
+
+impl<'a> Config<'a> {
+    pub(crate) fn new(
+        s: &'a str,
+        template_whitespace: Option<&String>,
+    ) -> std::result::Result<Config<'a>, CompileError> {
+        let root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
+        let default_dirs = vec![root.join("templates")];
+
+        let mut syntaxes = BTreeMap::new();
+        syntaxes.insert(DEFAULT_SYNTAX_NAME.to_string(), Syntax::default());
+
+        let raw = if s.is_empty() {
+            RawConfig::default()
+        } else {
+            RawConfig::from_toml_str(s)?
+        };
+
+        let (dirs, default_syntax, mut whitespace) = match raw.general {
+            Some(General {
+                dirs,
+                default_syntax,
+                whitespace,
+            }) => (
+                dirs.map_or(default_dirs, |v| {
+                    v.into_iter().map(|dir| root.join(dir)).collect()
+                }),
+                default_syntax.unwrap_or(DEFAULT_SYNTAX_NAME),
+                whitespace,
+            ),
+            None => (
+                default_dirs,
+                DEFAULT_SYNTAX_NAME,
+                WhitespaceHandling::default(),
+            ),
+        };
+        if let Some(template_whitespace) = template_whitespace {
+            whitespace = match template_whitespace.as_str() {
+                "suppress" => WhitespaceHandling::Suppress,
+                "minimize" => WhitespaceHandling::Minimize,
+                "preserve" => WhitespaceHandling::Preserve,
+                s => return Err(format!("invalid value for `whitespace`: \"{s}\"").into()),
+            };
+        }
+
+        if let Some(raw_syntaxes) = raw.syntax {
+            for raw_s in raw_syntaxes {
+                let name = raw_s.name;
+
+                if syntaxes
+                    .insert(name.to_string(), Syntax::try_from(raw_s)?)
+                    .is_some()
+                {
+                    return Err(format!("syntax \"{name}\" is already defined").into());
+                }
+            }
+        }
+
+        if !syntaxes.contains_key(default_syntax) {
+            return Err(format!("default syntax \"{default_syntax}\" not found").into());
+        }
+
+        let mut escapers = Vec::new();
+        if let Some(configured) = raw.escaper {
+            for escaper in configured {
+                escapers.push((
+                    escaper
+                        .extensions
+                        .iter()
+                        .map(|ext| (*ext).to_string())
+                        .collect(),
+                    escaper.path.to_string(),
+                ));
+            }
+        }
+        for (extensions, path) in DEFAULT_ESCAPERS {
+            escapers.push((str_set(extensions), (*path).to_string()));
+        }
+
+        Ok(Config {
+            dirs,
+            syntaxes,
+            default_syntax,
+            escapers,
+            whitespace,
+        })
+    }
+
+    pub(crate) fn find_template(
+        &self,
+        path: &str,
+        start_at: Option<&Path>,
+    ) -> std::result::Result<PathBuf, CompileError> {
+        if let Some(root) = start_at {
+            let relative = root.with_file_name(path);
+            if relative.exists() {
+                return Ok(relative);
+            }
+        }
+
+        for dir in &self.dirs {
+            let rooted = dir.join(path);
+            if rooted.exists() {
+                return Ok(rooted);
+            }
+        }
+
+        Err(format!(
+            "template {:?} not found in directories {:?}",
+            path, self.dirs
+        )
+        .into())
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct Syntax<'a> {
+    pub(crate) block_start: &'a str,
+    pub(crate) block_end: &'a str,
+    pub(crate) expr_start: &'a str,
+    pub(crate) expr_end: &'a str,
+    pub(crate) comment_start: &'a str,
+    pub(crate) comment_end: &'a str,
+}
+
+impl Default for Syntax<'static> {
+    fn default() -> Self {
+        Self {
+            block_start: "{%",
+            block_end: "%}",
+            expr_start: "{{",
+            expr_end: "}}",
+            comment_start: "{#",
+            comment_end: "#}",
+        }
+    }
+}
+
+impl<'a> TryFrom<RawSyntax<'a>> for Syntax<'a> {
+    type Error = CompileError;
+
+    fn try_from(raw: RawSyntax<'a>) -> std::result::Result<Self, Self::Error> {
+        let default = Syntax::default();
+        let syntax = Self {
+            block_start: raw.block_start.unwrap_or(default.block_start),
+            block_end: raw.block_end.unwrap_or(default.block_end),
+            expr_start: raw.expr_start.unwrap_or(default.expr_start),
+            expr_end: raw.expr_end.unwrap_or(default.expr_end),
+            comment_start: raw.comment_start.unwrap_or(default.comment_start),
+            comment_end: raw.comment_end.unwrap_or(default.comment_end),
+        };
+
+        if syntax.block_start.len() != 2
+            || syntax.block_end.len() != 2
+            || syntax.expr_start.len() != 2
+            || syntax.expr_end.len() != 2
+            || syntax.comment_start.len() != 2
+            || syntax.comment_end.len() != 2
+        {
+            return Err("length of delimiters must be two".into());
+        }
+
+        let bs = syntax.block_start.as_bytes()[0];
+        let be = syntax.block_start.as_bytes()[1];
+        let cs = syntax.comment_start.as_bytes()[0];
+        let ce = syntax.comment_start.as_bytes()[1];
+        let es = syntax.expr_start.as_bytes()[0];
+        let ee = syntax.expr_start.as_bytes()[1];
+        if !((bs == cs && bs == es) || (be == ce && be == ee)) {
+            return Err(format!("bad delimiters block_start: {}, comment_start: {}, expr_start: {}, needs one of the two characters in common", syntax.block_start, syntax.comment_start, syntax.expr_start).into());
+        }
+
+        Ok(syntax)
+    }
+}
+
+#[cfg_attr(feature = "serde", derive(Deserialize))]
+#[derive(Default)]
+struct RawConfig<'a> {
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    general: Option<General<'a>>,
+    syntax: Option<Vec<RawSyntax<'a>>>,
+    escaper: Option<Vec<RawEscaper<'a>>>,
+}
+
+impl RawConfig<'_> {
+    #[cfg(feature = "config")]
+    fn from_toml_str(s: &str) -> std::result::Result<RawConfig<'_>, CompileError> {
+        basic_toml::from_str(s)
+            .map_err(|e| format!("invalid TOML in {CONFIG_FILE_NAME}: {e}").into())
+    }
+
+    #[cfg(not(feature = "config"))]
+    fn from_toml_str(_: &str) -> std::result::Result<RawConfig<'_>, CompileError> {
+        Err("TOML support not available".into())
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+#[cfg_attr(feature = "serde", derive(Deserialize))]
+#[cfg_attr(feature = "serde", serde(field_identifier, rename_all = "lowercase"))]
+pub(crate) enum WhitespaceHandling {
+    /// The default behaviour. It will leave the whitespace characters "as is".
+    Preserve,
+    /// It'll remove all the whitespace characters before and after the jinja block.
+    Suppress,
+    /// It'll remove all the whitespace characters except one before and after the jinja blocks.
+    /// If there is a newline character, the preserved character in the trimmed characters, it will
+    /// the one preserved.
+    Minimize,
+}
+
+impl Default for WhitespaceHandling {
+    fn default() -> Self {
+        WhitespaceHandling::Preserve
+    }
+}
+
+#[cfg_attr(feature = "serde", derive(Deserialize))]
+struct General<'a> {
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    dirs: Option<Vec<&'a str>>,
+    default_syntax: Option<&'a str>,
+    #[cfg_attr(feature = "serde", serde(default))]
+    whitespace: WhitespaceHandling,
+}
+
+#[cfg_attr(feature = "serde", derive(Deserialize))]
+struct RawSyntax<'a> {
+    name: &'a str,
+    block_start: Option<&'a str>,
+    block_end: Option<&'a str>,
+    expr_start: Option<&'a str>,
+    expr_end: Option<&'a str>,
+    comment_start: Option<&'a str>,
+    comment_end: Option<&'a str>,
+}
+
+#[cfg_attr(feature = "serde", derive(Deserialize))]
+struct RawEscaper<'a> {
+    path: &'a str,
+    extensions: Vec<&'a str>,
+}
+
+pub(crate) fn read_config_file(
+    config_path: Option<&str>,
+) -> std::result::Result<String, CompileError> {
+    let root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
+    let filename = match config_path {
+        Some(config_path) => root.join(config_path),
+        None => root.join(CONFIG_FILE_NAME),
+    };
+
+    if filename.exists() {
+        fs::read_to_string(&filename)
+            .map_err(|_| format!("unable to read {:?}", filename.to_str().unwrap()).into())
+    } else if config_path.is_some() {
+        Err(format!("`{}` does not exist", root.display()).into())
+    } else {
+        Ok("".to_string())
+    }
+}
+
+fn str_set<T>(vals: &[T]) -> HashSet<String>
+where
+    T: ToString,
+{
+    vals.iter().map(|s| s.to_string()).collect()
+}
+
+#[allow(clippy::match_wild_err_arm)]
+pub(crate) fn get_template_source(tpl_path: &Path) -> std::result::Result<String, CompileError> {
+    match fs::read_to_string(tpl_path) {
+        Err(_) => Err(format!(
+            "unable to open template file '{}'",
+            tpl_path.to_str().unwrap()
+        )
+        .into()),
+        Ok(mut source) => {
+            if source.ends_with('\n') {
+                let _ = source.pop();
+            }
+            Ok(source)
+        }
+    }
+}
+
+static CONFIG_FILE_NAME: &str = "askama.toml";
+static DEFAULT_SYNTAX_NAME: &str = "default";
+static DEFAULT_ESCAPERS: &[(&[&str], &str)] = &[
+    (&["html", "htm", "xml"], "::askama::Html"),
+    (&["md", "none", "txt", "yml", ""], "::askama::Text"),
+    (&["j2", "jinja", "jinja2"], "::askama::Html"),
+];
+
+#[cfg(test)]
+mod tests {
+    use std::env;
+    use std::path::{Path, PathBuf};
+
+    use super::*;
+
+    #[test]
+    fn get_source() {
+        let path = Config::new("", None)
+            .and_then(|config| config.find_template("b.html", None))
+            .unwrap();
+        assert_eq!(get_template_source(&path).unwrap(), "bar");
+    }
+
+    #[test]
+    fn test_default_config() {
+        let mut root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
+        root.push("templates");
+        let config = Config::new("", None).unwrap();
+        assert_eq!(config.dirs, vec![root]);
+    }
+
+    #[cfg(feature = "config")]
+    #[test]
+    fn test_config_dirs() {
+        let mut root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
+        root.push("tpl");
+        let config = Config::new("[general]\ndirs = [\"tpl\"]", None).unwrap();
+        assert_eq!(config.dirs, vec![root]);
+    }
+
+    fn assert_eq_rooted(actual: &Path, expected: &str) {
+        let mut root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
+        root.push("templates");
+        let mut inner = PathBuf::new();
+        inner.push(expected);
+        assert_eq!(actual.strip_prefix(root).unwrap(), inner);
+    }
+
+    #[test]
+    fn find_absolute() {
+        let config = Config::new("", None).unwrap();
+        let root = config.find_template("a.html", None).unwrap();
+        let path = config.find_template("sub/b.html", Some(&root)).unwrap();
+        assert_eq_rooted(&path, "sub/b.html");
+    }
+
+    #[test]
+    #[should_panic]
+    fn find_relative_nonexistent() {
+        let config = Config::new("", None).unwrap();
+        let root = config.find_template("a.html", None).unwrap();
+        config.find_template("c.html", Some(&root)).unwrap();
+    }
+
+    #[test]
+    fn find_relative() {
+        let config = Config::new("", None).unwrap();
+        let root = config.find_template("sub/b.html", None).unwrap();
+        let path = config.find_template("c.html", Some(&root)).unwrap();
+        assert_eq_rooted(&path, "sub/c.html");
+    }
+
+    #[test]
+    fn find_relative_sub() {
+        let config = Config::new("", None).unwrap();
+        let root = config.find_template("sub/b.html", None).unwrap();
+        let path = config.find_template("sub1/d.html", Some(&root)).unwrap();
+        assert_eq_rooted(&path, "sub/sub1/d.html");
+    }
+
+    #[cfg(feature = "config")]
+    #[test]
+    fn add_syntax() {
+        let raw_config = r#"
+        [general]
+        default_syntax = "foo"
+
+        [[syntax]]
+        name = "foo"
+        block_start = "{<"
+
+        [[syntax]]
+        name = "bar"
+        expr_start = "{!"
+        "#;
+
+        let default_syntax = Syntax::default();
+        let config = Config::new(raw_config, None).unwrap();
+        assert_eq!(config.default_syntax, "foo");
+
+        let foo = config.syntaxes.get("foo").unwrap();
+        assert_eq!(foo.block_start, "{<");
+        assert_eq!(foo.block_end, default_syntax.block_end);
+        assert_eq!(foo.expr_start, default_syntax.expr_start);
+        assert_eq!(foo.expr_end, default_syntax.expr_end);
+        assert_eq!(foo.comment_start, default_syntax.comment_start);
+        assert_eq!(foo.comment_end, default_syntax.comment_end);
+
+        let bar = config.syntaxes.get("bar").unwrap();
+        assert_eq!(bar.block_start, default_syntax.block_start);
+        assert_eq!(bar.block_end, default_syntax.block_end);
+        assert_eq!(bar.expr_start, "{!");
+        assert_eq!(bar.expr_end, default_syntax.expr_end);
+        assert_eq!(bar.comment_start, default_syntax.comment_start);
+        assert_eq!(bar.comment_end, default_syntax.comment_end);
+    }
+
+    #[cfg(feature = "config")]
+    #[test]
+    fn add_syntax_two() {
+        let raw_config = r#"
+        syntax = [{ name = "foo", block_start = "{<" },
+                  { name = "bar", expr_start = "{!" } ]
+
+        [general]
+        default_syntax = "foo"
+        "#;
+
+        let default_syntax = Syntax::default();
+        let config = Config::new(raw_config, None).unwrap();
+        assert_eq!(config.default_syntax, "foo");
+
+        let foo = config.syntaxes.get("foo").unwrap();
+        assert_eq!(foo.block_start, "{<");
+        assert_eq!(foo.block_end, default_syntax.block_end);
+        assert_eq!(foo.expr_start, default_syntax.expr_start);
+        assert_eq!(foo.expr_end, default_syntax.expr_end);
+        assert_eq!(foo.comment_start, default_syntax.comment_start);
+        assert_eq!(foo.comment_end, default_syntax.comment_end);
+
+        let bar = config.syntaxes.get("bar").unwrap();
+        assert_eq!(bar.block_start, default_syntax.block_start);
+        assert_eq!(bar.block_end, default_syntax.block_end);
+        assert_eq!(bar.expr_start, "{!");
+        assert_eq!(bar.expr_end, default_syntax.expr_end);
+        assert_eq!(bar.comment_start, default_syntax.comment_start);
+        assert_eq!(bar.comment_end, default_syntax.comment_end);
+    }
+
+    #[cfg(feature = "toml")]
+    #[should_panic]
+    #[test]
+    fn use_default_at_syntax_name() {
+        let raw_config = r#"
+        syntax = [{ name = "default" }]
+        "#;
+
+        let _config = Config::new(raw_config, None).unwrap();
+    }
+
+    #[cfg(feature = "toml")]
+    #[should_panic]
+    #[test]
+    fn duplicated_syntax_name_on_list() {
+        let raw_config = r#"
+        syntax = [{ name = "foo", block_start = "~<" },
+                  { name = "foo", block_start = "%%" } ]
+        "#;
+
+        let _config = Config::new(raw_config, None).unwrap();
+    }
+
+    #[cfg(feature = "toml")]
+    #[should_panic]
+    #[test]
+    fn is_not_exist_default_syntax() {
+        let raw_config = r#"
+        [general]
+        default_syntax = "foo"
+        "#;
+
+        let _config = Config::new(raw_config, None).unwrap();
+    }
+
+    #[cfg(feature = "config")]
+    #[test]
+    fn escape_modes() {
+        let config = Config::new(
+            r#"
+            [[escaper]]
+            path = "::askama::Js"
+            extensions = ["js"]
+        "#,
+            None,
+        )
+        .unwrap();
+        assert_eq!(
+            config.escapers,
+            vec![
+                (str_set(&["js"]), "::askama::Js".into()),
+                (str_set(&["html", "htm", "xml"]), "::askama::Html".into()),
+                (
+                    str_set(&["md", "none", "txt", "yml", ""]),
+                    "::askama::Text".into()
+                ),
+                (str_set(&["j2", "jinja", "jinja2"]), "::askama::Html".into()),
+            ]
+        );
+    }
+
+    #[cfg(feature = "config")]
+    #[test]
+    fn test_whitespace_parsing() {
+        let config = Config::new(
+            r#"
+            [general]
+            whitespace = "suppress"
+            "#,
+            None,
+        )
+        .unwrap();
+        assert_eq!(config.whitespace, WhitespaceHandling::Suppress);
+
+        let config = Config::new(r#""#, None).unwrap();
+        assert_eq!(config.whitespace, WhitespaceHandling::Preserve);
+
+        let config = Config::new(
+            r#"
+            [general]
+            whitespace = "preserve"
+            "#,
+            None,
+        )
+        .unwrap();
+        assert_eq!(config.whitespace, WhitespaceHandling::Preserve);
+
+        let config = Config::new(
+            r#"
+            [general]
+            whitespace = "minimize"
+            "#,
+            None,
+        )
+        .unwrap();
+        assert_eq!(config.whitespace, WhitespaceHandling::Minimize);
+    }
+
+    #[cfg(feature = "toml")]
+    #[test]
+    fn test_whitespace_in_template() {
+        // Checking that template arguments have precedence over general configuration.
+        // So in here, in the template arguments, there is `whitespace = "minimize"` so
+        // the `WhitespaceHandling` should be `Minimize` as well.
+        let config = Config::new(
+            r#"
+            [general]
+            whitespace = "suppress"
+            "#,
+            Some(&"minimize".to_owned()),
+        )
+        .unwrap();
+        assert_eq!(config.whitespace, WhitespaceHandling::Minimize);
+
+        let config = Config::new(r#""#, Some(&"minimize".to_owned())).unwrap();
+        assert_eq!(config.whitespace, WhitespaceHandling::Minimize);
+    }
+
+    #[test]
+    fn test_config_whitespace_error() {
+        let config = Config::new(r#""#, Some(&"trim".to_owned()));
+        if let Err(err) = config {
+            assert_eq!(err.msg, "invalid value for `whitespace`: \"trim\"");
+        } else {
+            panic!("Config::new should have return an error");
+        }
+    }
+}
diff --git a/third_party/rust/askama_derive/src/generator.rs b/third_party/rust/askama_derive/src/generator.rs
new file mode 100644
index 0000000000..05b3fc3245
--- /dev/null
+++ b/third_party/rust/askama_derive/src/generator.rs
@@ -0,0 +1,2171 @@
+use crate::config::{get_template_source, read_config_file, Config, WhitespaceHandling};
+use crate::heritage::{Context, Heritage};
+use crate::input::{Print, Source, TemplateInput};
+use crate::parser::{parse, Cond, CondTest, Expr, Loop, Node, Target, When, Whitespace, Ws};
+use crate::CompileError;
+
+use proc_macro::TokenStream;
+use quote::{quote, ToTokens};
+use syn::punctuated::Punctuated;
+
+use std::collections::hash_map::{Entry, HashMap};
+use std::path::{Path, PathBuf};
+use std::{cmp, hash, mem, str};
+
+/// The actual implementation for askama_derive::Template
+pub(crate) fn derive_template(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput = syn::parse(input).unwrap();
+    match build_template(&ast) {
+        Ok(source) => source.parse().unwrap(),
+        Err(e) => e.into_compile_error(),
+    }
+}
+
+/// Takes a `syn::DeriveInput` and generates source code for it
+///
+/// Reads the metadata from the `template()` attribute to get the template
+/// metadata, then fetches the source from the filesystem. The source is
+/// parsed, and the parse tree is fed to the code generator. Will print
+/// the parse tree and/or generated source according to the `print` key's
+/// value as passed to the `template()` attribute.
+fn build_template(ast: &syn::DeriveInput) -> Result<String, CompileError> {
+    let template_args = TemplateArgs::new(ast)?;
+    let config_toml = read_config_file(template_args.config_path.as_deref())?;
+    let config = Config::new(&config_toml, template_args.whitespace.as_ref())?;
+    let input = TemplateInput::new(ast, &config, template_args)?;
+    let source: String = match input.source {
+        Source::Source(ref s) => s.clone(),
+        Source::Path(_) => get_template_source(&input.path)?,
+    };
+
+    let mut sources = HashMap::new();
+    find_used_templates(&input, &mut sources, source)?;
+
+    let mut parsed = HashMap::new();
+    for (path, src) in &sources {
+        parsed.insert(path.as_path(), parse(src, input.syntax)?);
+    }
+
+    let mut contexts = HashMap::new();
+    for (path, nodes) in &parsed {
+        contexts.insert(*path, Context::new(input.config, path, nodes)?);
+    }
+
+    let ctx = &contexts[input.path.as_path()];
+    let heritage = if !ctx.blocks.is_empty() || ctx.extends.is_some() {
+        Some(Heritage::new(ctx, &contexts))
+    } else {
+        None
+    };
+
+    if input.print == Print::Ast || input.print == Print::All {
+        eprintln!("{:?}", parsed[input.path.as_path()]);
+    }
+
+    let code = Generator::new(
+        &input,
+        &contexts,
+        heritage.as_ref(),
+        MapChain::new(),
+        config.whitespace,
+    )
+    .build(&contexts[input.path.as_path()])?;
+    if input.print == Print::Code || input.print == Print::All {
+        eprintln!("{code}");
+    }
+    Ok(code)
+}
+
+#[derive(Default)]
+pub(crate) struct TemplateArgs {
+    pub(crate) source: Option<Source>,
+    pub(crate) print: Print,
+    pub(crate) escaping: Option<String>,
+    pub(crate) ext: Option<String>,
+    pub(crate) syntax: Option<String>,
+    pub(crate) config_path: Option<String>,
+    pub(crate) whitespace: Option<String>,
+}
+
+impl TemplateArgs {
+    fn new(ast: &'_ syn::DeriveInput) -> Result<Self, CompileError> {
+        // Check that an attribute called `template()` exists once and that it is
+        // the proper type (list).
+        let mut template_args = None;
+        for attr in &ast.attrs {
+            if !attr.path().is_ident("template") {
+                continue;
+            }
+
+            match attr.parse_args_with(Punctuated::<syn::Meta, syn::Token![,]>::parse_terminated) {
+                Ok(args) if template_args.is_none() => template_args = Some(args),
+                Ok(_) => return Err("duplicated 'template' attribute".into()),
+                Err(e) => return Err(format!("unable to parse template arguments: {e}").into()),
+            };
+        }
+
+        let template_args =
+            template_args.ok_or_else(|| CompileError::from("no attribute 'template' found"))?;
+
+        let mut args = Self::default();
+        // Loop over the meta attributes and find everything that we
+        // understand. Return a CompileError if something is not right.
+        // `source` contains an enum that can represent `path` or `source`.
+        for item in template_args {
+            let pair = match item {
+                syn::Meta::NameValue(pair) => pair,
+                _ => {
+                    return Err(format!(
+                        "unsupported attribute argument {:?}",
+                        item.to_token_stream()
+                    )
+                    .into())
+                }
+            };
+
+            let ident = match pair.path.get_ident() {
+                Some(ident) => ident,
+                None => unreachable!("not possible in syn::Meta::NameValue(…)"),
+            };
+
+            let value = match pair.value {
+                syn::Expr::Lit(lit) => lit,
+                syn::Expr::Group(group) => match *group.expr {
+                    syn::Expr::Lit(lit) => lit,
+                    _ => {
+                        return Err(format!("unsupported argument value type for {ident:?}").into())
+                    }
+                },
+                _ => return Err(format!("unsupported argument value type for {ident:?}").into()),
+            };
+
+            if ident == "path" {
+                if let syn::Lit::Str(s) = value.lit {
+                    if args.source.is_some() {
+                        return Err("must specify 'source' or 'path', not both".into());
+                    }
+                    args.source = Some(Source::Path(s.value()));
+                } else {
+                    return Err("template path must be string literal".into());
+                }
+            } else if ident == "source" {
+                if let syn::Lit::Str(s) = value.lit {
+                    if args.source.is_some() {
+                        return Err("must specify 'source' or 'path', not both".into());
+                    }
+                    args.source = Some(Source::Source(s.value()));
+                } else {
+                    return Err("template source must be string literal".into());
+                }
+            } else if ident == "print" {
+                if let syn::Lit::Str(s) = value.lit {
+                    args.print = s.value().parse()?;
+                } else {
+                    return Err("print value must be string literal".into());
+                }
+            } else if ident == "escape" {
+                if let syn::Lit::Str(s) = value.lit {
+                    args.escaping = Some(s.value());
+                } else {
+                    return Err("escape value must be string literal".into());
+                }
+            } else if ident == "ext" {
+                if let syn::Lit::Str(s) = value.lit {
+                    args.ext = Some(s.value());
+                } else {
+                    return Err("ext value must be string literal".into());
+                }
+            } else if ident == "syntax" {
+                if let syn::Lit::Str(s) = value.lit {
+                    args.syntax = Some(s.value())
+                } else {
+                    return Err("syntax value must be string literal".into());
+                }
+            } else if ident == "config" {
+                if let syn::Lit::Str(s) = value.lit {
+                    args.config_path = Some(s.value())
+                } else {
+                    return Err("config value must be string literal".into());
+                }
+            } else if ident == "whitespace" {
+                if let syn::Lit::Str(s) = value.lit {
+                    args.whitespace = Some(s.value())
+                } else {
+                    return Err("whitespace value must be string literal".into());
+                }
+            } else {
+                return Err(format!("unsupported attribute key {ident:?} found").into());
+            }
+        }
+
+        Ok(args)
+    }
+}
+
+fn find_used_templates(
+    input: &TemplateInput<'_>,
+    map: &mut HashMap<PathBuf, String>,
+    source: String,
+) -> Result<(), CompileError> {
+    let mut dependency_graph = Vec::new();
+    let mut check = vec![(input.path.clone(), source)];
+    while let Some((path, source)) = check.pop() {
+        for n in parse(&source, input.syntax)? {
+            match n {
+                Node::Extends(extends) => {
+                    let extends = input.config.find_template(extends, Some(&path))?;
+                    let dependency_path = (path.clone(), extends.clone());
+                    if dependency_graph.contains(&dependency_path) {
+                        return Err(format!(
+                            "cyclic dependency in graph {:#?}",
+                            dependency_graph
+                                .iter()
+                                .map(|e| format!("{:#?} --> {:#?}", e.0, e.1))
+                                .collect::<Vec<String>>()
+                        )
+                        .into());
+                    }
+                    dependency_graph.push(dependency_path);
+                    let source = get_template_source(&extends)?;
+                    check.push((extends, source));
+                }
+                Node::Import(_, import, _) => {
+                    let import = input.config.find_template(import, Some(&path))?;
+                    let source = get_template_source(&import)?;
+                    check.push((import, source));
+                }
+                _ => {}
+            }
+        }
+        map.insert(path, source);
+    }
+    Ok(())
+}
+
+struct Generator<'a> {
+    // The template input state: original struct AST and attributes
+    input: &'a TemplateInput<'a>,
+    // All contexts, keyed by the package-relative template path
+    contexts: &'a HashMap<&'a Path, Context<'a>>,
+    // The heritage contains references to blocks and their ancestry
+    heritage: Option<&'a Heritage<'a>>,
+    // Variables accessible directly from the current scope (not redirected to context)
+    locals: MapChain<'a, &'a str, LocalMeta>,
+    // Suffix whitespace from the previous literal. Will be flushed to the
+    // output buffer unless suppressed by whitespace suppression on the next
+    // non-literal.
+    next_ws: Option<&'a str>,
+    // Whitespace suppression from the previous non-literal. Will be used to
+    // determine whether to flush prefix whitespace from the next literal.
+    skip_ws: WhitespaceHandling,
+    // If currently in a block, this will contain the name of a potential parent block
+    super_block: Option<(&'a str, usize)>,
+    // buffer for writable
+    buf_writable: Vec<Writable<'a>>,
+    // Counter for write! hash named arguments
+    named: usize,
+    // If set to `suppress`, the whitespace characters will be removed by default unless `+` is
+    // used.
+    whitespace: WhitespaceHandling,
+}
+
+impl<'a> Generator<'a> {
+    fn new<'n>(
+        input: &'n TemplateInput<'_>,
+        contexts: &'n HashMap<&'n Path, Context<'n>>,
+        heritage: Option<&'n Heritage<'_>>,
+        locals: MapChain<'n, &'n str, LocalMeta>,
+        whitespace: WhitespaceHandling,
+    ) -> Generator<'n> {
+        Generator {
+            input,
+            contexts,
+            heritage,
+            locals,
+            next_ws: None,
+            skip_ws: WhitespaceHandling::Preserve,
+            super_block: None,
+            buf_writable: vec![],
+            named: 0,
+            whitespace,
+        }
+    }
+
+    fn child(&mut self) -> Generator<'_> {
+        let locals = MapChain::with_parent(&self.locals);
+        Self::new(
+            self.input,
+            self.contexts,
+            self.heritage,
+            locals,
+            self.whitespace,
+        )
+    }
+
+    // Takes a Context and generates the relevant implementations.
+    fn build(mut self, ctx: &'a Context<'_>) -> Result<String, CompileError> {
+        let mut buf = Buffer::new(0);
+
+        self.impl_template(ctx, &mut buf)?;
+        self.impl_display(&mut buf)?;
+
+        #[cfg(feature = "with-actix-web")]
+        self.impl_actix_web_responder(&mut buf)?;
+        #[cfg(feature = "with-axum")]
+        self.impl_axum_into_response(&mut buf)?;
+        #[cfg(feature = "with-gotham")]
+        self.impl_gotham_into_response(&mut buf)?;
+        #[cfg(feature = "with-hyper")]
+        self.impl_hyper_into_response(&mut buf)?;
+        #[cfg(feature = "with-mendes")]
+        self.impl_mendes_responder(&mut buf)?;
+        #[cfg(feature = "with-rocket")]
+        self.impl_rocket_responder(&mut buf)?;
+        #[cfg(feature = "with-tide")]
+        self.impl_tide_integrations(&mut buf)?;
+        #[cfg(feature = "with-warp")]
+        self.impl_warp_reply(&mut buf)?;
+
+        Ok(buf.buf)
+    }
+
+    // Implement `Template` for the given context struct.
+    fn impl_template(
+        &mut self,
+        ctx: &'a Context<'_>,
+        buf: &mut Buffer,
+    ) -> Result<(), CompileError> {
+        self.write_header(buf, "::askama::Template", None)?;
+        buf.writeln(
+            "fn render_into(&self, writer: &mut (impl ::std::fmt::Write + ?Sized)) -> \
+             ::askama::Result<()> {",
+        )?;
+
+        // Make sure the compiler understands that the generated code depends on the template files.
+        for path in self.contexts.keys() {
+            // Skip the fake path of templates defined in rust source.
+            let path_is_valid = match self.input.source {
+                Source::Path(_) => true,
+                Source::Source(_) => path != &self.input.path,
+            };
+            if path_is_valid {
+                let path = path.to_str().unwrap();
+                buf.writeln(
+                    &quote! {
+                        include_bytes!(#path);
+                    }
+                    .to_string(),
+                )?;
+            }
+        }
+
+        let size_hint = if let Some(heritage) = self.heritage {
+            self.handle(heritage.root, heritage.root.nodes, buf, AstLevel::Top)
+        } else {
+            self.handle(ctx, ctx.nodes, buf, AstLevel::Top)
+        }?;
+
+        self.flush_ws(Ws(None, None));
+        buf.writeln("::askama::Result::Ok(())")?;
+        buf.writeln("}")?;
+
+        buf.writeln("const EXTENSION: ::std::option::Option<&'static ::std::primitive::str> = ")?;
+        buf.writeln(&format!("{:?}", self.input.extension()))?;
+        buf.writeln(";")?;
+
+        buf.writeln("const SIZE_HINT: ::std::primitive::usize = ")?;
+        buf.writeln(&format!("{size_hint}"))?;
+        buf.writeln(";")?;
+
+        buf.writeln("const MIME_TYPE: &'static ::std::primitive::str = ")?;
+        buf.writeln(&format!("{:?}", &self.input.mime_type))?;
+        buf.writeln(";")?;
+
+        buf.writeln("}")?;
+        Ok(())
+    }
+
+    // Implement `Display` for the given context struct.
+    fn impl_display(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        self.write_header(buf, "::std::fmt::Display", None)?;
+        buf.writeln("#[inline]")?;
+        buf.writeln("fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {")?;
+        buf.writeln("::askama::Template::render_into(self, f).map_err(|_| ::std::fmt::Error {})")?;
+        buf.writeln("}")?;
+        buf.writeln("}")
+    }
+
+    // Implement Actix-web's `Responder`.
+    #[cfg(feature = "with-actix-web")]
+    fn impl_actix_web_responder(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        self.write_header(buf, "::askama_actix::actix_web::Responder", None)?;
+        buf.writeln("type Body = ::askama_actix::actix_web::body::BoxBody;")?;
+        buf.writeln("#[inline]")?;
+        buf.writeln(
+            "fn respond_to(self, _req: &::askama_actix::actix_web::HttpRequest) \
+             -> ::askama_actix::actix_web::HttpResponse<Self::Body> {",
+        )?;
+        buf.writeln("<Self as ::askama_actix::TemplateToResponse>::to_response(&self)")?;
+        buf.writeln("}")?;
+        buf.writeln("}")
+    }
+
+    // Implement Axum's `IntoResponse`.
+    #[cfg(feature = "with-axum")]
+    fn impl_axum_into_response(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        self.write_header(buf, "::askama_axum::IntoResponse", None)?;
+        buf.writeln("#[inline]")?;
+        buf.writeln(
+            "fn into_response(self)\
+             -> ::askama_axum::Response {",
+        )?;
+        buf.writeln("::askama_axum::into_response(&self)")?;
+        buf.writeln("}")?;
+        buf.writeln("}")
+    }
+
+    // Implement gotham's `IntoResponse`.
+    #[cfg(feature = "with-gotham")]
+    fn impl_gotham_into_response(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        self.write_header(buf, "::askama_gotham::IntoResponse", None)?;
+        buf.writeln("#[inline]")?;
+        buf.writeln(
+            "fn into_response(self, _state: &::askama_gotham::State)\
+             -> ::askama_gotham::Response<::askama_gotham::Body> {",
+        )?;
+        buf.writeln("::askama_gotham::respond(&self)")?;
+        buf.writeln("}")?;
+        buf.writeln("}")
+    }
+
+    // Implement `From<Template> for hyper::Response<Body>` and `From<Template> for hyper::Body.
+    #[cfg(feature = "with-hyper")]
+    fn impl_hyper_into_response(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        let (impl_generics, orig_ty_generics, where_clause) =
+            self.input.ast.generics.split_for_impl();
+        let ident = &self.input.ast.ident;
+        // From<Template> for hyper::Response<Body>
+        buf.writeln(&format!(
+            "{} {{",
+            quote!(
+                impl #impl_generics ::core::convert::From<&#ident #orig_ty_generics>
+                for ::askama_hyper::hyper::Response<::askama_hyper::hyper::Body>
+                #where_clause
+            )
+        ))?;
+        buf.writeln("#[inline]")?;
+        buf.writeln(&format!(
+            "{} {{",
+            quote!(fn from(value: &#ident #orig_ty_generics) -> Self)
+        ))?;
+        buf.writeln("::askama_hyper::respond(value)")?;
+        buf.writeln("}")?;
+        buf.writeln("}")?;
+
+        // TryFrom<Template> for hyper::Body
+        buf.writeln(&format!(
+            "{} {{",
+            quote!(
+                impl #impl_generics ::core::convert::TryFrom<&#ident #orig_ty_generics>
+                for ::askama_hyper::hyper::Body
+                #where_clause
+            )
+        ))?;
+        buf.writeln("type Error = ::askama::Error;")?;
+        buf.writeln("#[inline]")?;
+        buf.writeln(&format!(
+            "{} {{",
+            quote!(fn try_from(value: &#ident #orig_ty_generics) -> Result<Self, Self::Error>)
+        ))?;
+        buf.writeln("::askama::Template::render(value).map(Into::into)")?;
+        buf.writeln("}")?;
+        buf.writeln("}")
+    }
+
+    // Implement mendes' `Responder`.
+    #[cfg(feature = "with-mendes")]
+    fn impl_mendes_responder(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        let param = syn::parse_str("A: ::mendes::Application").unwrap();
+
+        let mut generics = self.input.ast.generics.clone();
+        generics.params.push(param);
+        let (_, orig_ty_generics, _) = self.input.ast.generics.split_for_impl();
+        let (impl_generics, _, where_clause) = generics.split_for_impl();
+
+        let mut where_clause = match where_clause {
+            Some(clause) => clause.clone(),
+            None => syn::WhereClause {
+                where_token: syn::Token![where](proc_macro2::Span::call_site()),
+                predicates: syn::punctuated::Punctuated::new(),
+            },
+        };
+
+        where_clause
+            .predicates
+            .push(syn::parse_str("A::ResponseBody: From<String>").unwrap());
+        where_clause
+            .predicates
+            .push(syn::parse_str("A::Error: From<::askama_mendes::Error>").unwrap());
+
+        buf.writeln(
+            format!(
+                "{} {} for {} {} {{",
+                quote!(impl #impl_generics),
+                "::mendes::application::IntoResponse<A>",
+                self.input.ast.ident,
+                quote!(#orig_ty_generics #where_clause),
+            )
+            .as_ref(),
+        )?;
+
+        buf.writeln(
+            "fn into_response(self, app: &A, req: &::mendes::http::request::Parts) \
+             -> ::mendes::http::Response<A::ResponseBody> {",
+        )?;
+
+        buf.writeln("::askama_mendes::into_response(app, req, &self)")?;
+        buf.writeln("}")?;
+        buf.writeln("}")?;
+        Ok(())
+    }
+
+    // Implement Rocket's `Responder`.
+    #[cfg(feature = "with-rocket")]
+    fn impl_rocket_responder(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        let lifetime = syn::Lifetime::new("'askama", proc_macro2::Span::call_site());
+        let param = syn::GenericParam::Lifetime(syn::LifetimeParam::new(lifetime));
+        self.write_header(
+            buf,
+            "::askama_rocket::Responder<'askama, 'askama>",
+            Some(vec![param]),
+        )?;
+
+        buf.writeln("#[inline]")?;
+        buf.writeln(
+            "fn respond_to(self, _: &::askama_rocket::Request) \
+             -> ::askama_rocket::Result<'askama> {",
+        )?;
+        buf.writeln("::askama_rocket::respond(&self)")?;
+
+        buf.writeln("}")?;
+        buf.writeln("}")?;
+        Ok(())
+    }
+
+    #[cfg(feature = "with-tide")]
+    fn impl_tide_integrations(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        self.write_header(
+            buf,
+            "::std::convert::TryInto<::askama_tide::tide::Body>",
+            None,
+        )?;
+        buf.writeln(
+            "type Error = ::askama_tide::askama::Error;\n\
+            #[inline]\n\
+            fn try_into(self) -> ::askama_tide::askama::Result<::askama_tide::tide::Body> {",
+        )?;
+        buf.writeln("::askama_tide::try_into_body(&self)")?;
+        buf.writeln("}")?;
+        buf.writeln("}")?;
+
+        buf.writeln("#[allow(clippy::from_over_into)]")?;
+        self.write_header(buf, "Into<::askama_tide::tide::Response>", None)?;
+        buf.writeln("#[inline]")?;
+        buf.writeln("fn into(self) -> ::askama_tide::tide::Response {")?;
+        buf.writeln("::askama_tide::into_response(&self)")?;
+        buf.writeln("}\n}")
+    }
+
+    #[cfg(feature = "with-warp")]
+    fn impl_warp_reply(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
+        self.write_header(buf, "::askama_warp::warp::reply::Reply", None)?;
+        buf.writeln("#[inline]")?;
+        buf.writeln("fn into_response(self) -> ::askama_warp::warp::reply::Response {")?;
+        buf.writeln("::askama_warp::reply(&self)")?;
+        buf.writeln("}")?;
+        buf.writeln("}")
+    }
+
+    // Writes header for the `impl` for `TraitFromPathName` or `Template`
+    // for the given context struct.
+    fn write_header(
+        &mut self,
+        buf: &mut Buffer,
+        target: &str,
+        params: Option<Vec<syn::GenericParam>>,
+    ) -> Result<(), CompileError> {
+        let mut generics = self.input.ast.generics.clone();
+        if let Some(params) = params {
+            for param in params {
+                generics.params.push(param);
+            }
+        }
+        let (_, orig_ty_generics, _) = self.input.ast.generics.split_for_impl();
+        let (impl_generics, _, where_clause) = generics.split_for_impl();
+        buf.writeln(
+            format!(
+                "{} {} for {}{} {{",
+                quote!(impl #impl_generics),
+                target,
+                self.input.ast.ident,
+                quote!(#orig_ty_generics #where_clause),
+            )
+            .as_ref(),
+        )
+    }
+
+    /* Helper methods for handling node types */
+
+    fn handle(
+        &mut self,
+        ctx: &'a Context<'_>,
+        nodes: &'a [Node<'_>],
+        buf: &mut Buffer,
+        level: AstLevel,
+    ) -> Result<usize, CompileError> {
+        let mut size_hint = 0;
+        for n in nodes {
+            match *n {
+                Node::Lit(lws, val, rws) => {
+                    self.visit_lit(lws, val, rws);
+                }
+                Node::Comment(ws) => {
+                    self.write_comment(ws);
+                }
+                Node::Expr(ws, ref val) => {
+                    self.write_expr(ws, val);
+                }
+                Node::LetDecl(ws, ref var) => {
+                    self.write_let_decl(buf, ws, var)?;
+                }
+                Node::Let(ws, ref var, ref val) => {
+                    self.write_let(buf, ws, var, val)?;
+                }
+                Node::Cond(ref conds, ws) => {
+                    size_hint += self.write_cond(ctx, buf, conds, ws)?;
+                }
+                Node::Match(ws1, ref expr, ref arms, ws2) => {
+                    size_hint += self.write_match(ctx, buf, ws1, expr, arms, ws2)?;
+                }
+                Node::Loop(ref loop_block) => {
+                    size_hint += self.write_loop(ctx, buf, loop_block)?;
+                }
+                Node::BlockDef(ws1, name, _, ws2) => {
+                    size_hint += self.write_block(buf, Some(name), Ws(ws1.0, ws2.1))?;
+                }
+                Node::Include(ws, path) => {
+                    size_hint += self.handle_include(ctx, buf, ws, path)?;
+                }
+                Node::Call(ws, scope, name, ref args) => {
+                    size_hint += self.write_call(ctx, buf, ws, scope, name, args)?;
+                }
+                Node::Macro(_, ref m) => {
+                    if level != AstLevel::Top {
+                        return Err("macro blocks only allowed at the top level".into());
+                    }
+                    self.flush_ws(m.ws1);
+                    self.prepare_ws(m.ws2);
+                }
+                Node::Raw(ws1, lws, val, rws, ws2) => {
+                    self.handle_ws(ws1);
+                    self.visit_lit(lws, val, rws);
+                    self.handle_ws(ws2);
+                }
+                Node::Import(ws, _, _) => {
+                    if level != AstLevel::Top {
+                        return Err("import blocks only allowed at the top level".into());
+                    }
+                    self.handle_ws(ws);
+                }
+                Node::Extends(_) => {
+                    if level != AstLevel::Top {
+                        return Err("extend blocks only allowed at the top level".into());
+                    }
+                    // No whitespace handling: child template top-level is not used,
+                    // except for the blocks defined in it.
+                }
+                Node::Break(ws) => {
+                    self.handle_ws(ws);
+                    self.write_buf_writable(buf)?;
+                    buf.writeln("break;")?;
+                }
+                Node::Continue(ws) => {
+                    self.handle_ws(ws);
+                    self.write_buf_writable(buf)?;
+                    buf.writeln("continue;")?;
+                }
+            }
+        }
+
+        if AstLevel::Top == level {
+            // Handle any pending whitespace.
+            if self.next_ws.is_some() {
+                self.flush_ws(Ws(Some(self.skip_ws.into()), None));
+            }
+
+            size_hint += self.write_buf_writable(buf)?;
+        }
+        Ok(size_hint)
+    }
+
+    fn write_cond(
+        &mut self,
+        ctx: &'a Context<'_>,
+        buf: &mut Buffer,
+        conds: &'a [Cond<'_>],
+        ws: Ws,
+    ) -> Result<usize, CompileError> {
+        let mut flushed = 0;
+        let mut arm_sizes = Vec::new();
+        let mut has_else = false;
+        for (i, &(cws, ref cond, ref nodes)) in conds.iter().enumerate() {
+            self.handle_ws(cws);
+            flushed += self.write_buf_writable(buf)?;
+            if i > 0 {
+                self.locals.pop();
+            }
+
+            self.locals.push();
+            let mut arm_size = 0;
+            if let Some(CondTest { target, expr }) = cond {
+                if i == 0 {
+                    buf.write("if ");
+                } else {
+                    buf.dedent()?;
+                    buf.write("} else if ");
+                }
+
+                if let Some(target) = target {
+                    let mut expr_buf = Buffer::new(0);
+                    self.visit_expr(&mut expr_buf, expr)?;
+                    buf.write("let ");
+                    self.visit_target(buf, true, true, target);
+                    buf.write(" = &(");
+                    buf.write(&expr_buf.buf);
+                    buf.write(")");
+                } else {
+                    // The following syntax `*(&(...) as &bool)` is used to
+                    // trigger Rust's automatic dereferencing, to coerce
+                    // e.g. `&&&&&bool` to `bool`. First `&(...) as &bool`
+                    // coerces e.g. `&&&bool` to `&bool`. Then `*(&bool)`
+                    // finally dereferences it to `bool`.
+                    buf.write("*(&(");
+                    let expr_code = self.visit_expr_root(expr)?;
+                    buf.write(&expr_code);
+                    buf.write(") as &bool)");
+                }
+            } else {
+                buf.dedent()?;
+                buf.write("} else");
+                has_else = true;
+            }
+
+            buf.writeln(" {")?;
+
+            arm_size += self.handle(ctx, nodes, buf, AstLevel::Nested)?;
+            arm_sizes.push(arm_size);
+        }
+        self.handle_ws(ws);
+        flushed += self.write_buf_writable(buf)?;
+        buf.writeln("}")?;
+
+        self.locals.pop();
+
+        if !has_else {
+            arm_sizes.push(0);
+        }
+        Ok(flushed + median(&mut arm_sizes))
+    }
+
+    #[allow(clippy::too_many_arguments)]
+    fn write_match(
+        &mut self,
+        ctx: &'a Context<'_>,
+        buf: &mut Buffer,
+        ws1: Ws,
+        expr: &Expr<'_>,
+        arms: &'a [When<'_>],
+        ws2: Ws,
+    ) -> Result<usize, CompileError> {
+        self.flush_ws(ws1);
+        let flushed = self.write_buf_writable(buf)?;
+        let mut arm_sizes = Vec::new();
+
+        let expr_code = self.visit_expr_root(expr)?;
+        buf.writeln(&format!("match &{expr_code} {{"))?;
+
+        let mut arm_size = 0;
+        for (i, arm) in arms.iter().enumerate() {
+            let &(ws, ref target, ref body) = arm;
+            self.handle_ws(ws);
+
+            if i > 0 {
+                arm_sizes.push(arm_size + self.write_buf_writable(buf)?);
+
+                buf.writeln("}")?;
+                self.locals.pop();
+            }
+
+            self.locals.push();
+            self.visit_target(buf, true, true, target);
+            buf.writeln(" => {")?;
+
+            arm_size = self.handle(ctx, body, buf, AstLevel::Nested)?;
+        }
+
+        self.handle_ws(ws2);
+        arm_sizes.push(arm_size + self.write_buf_writable(buf)?);
+        buf.writeln("}")?;
+        self.locals.pop();
+
+        buf.writeln("}")?;
+
+        Ok(flushed + median(&mut arm_sizes))
+    }
+
+    #[allow(clippy::too_many_arguments)]
+    fn write_loop(
+        &mut self,
+        ctx: &'a Context<'_>,
+        buf: &mut Buffer,
+        loop_block: &'a Loop<'_>,
+    ) -> Result<usize, CompileError> {
+        self.handle_ws(loop_block.ws1);
+        self.locals.push();
+
+        let expr_code = self.visit_expr_root(&loop_block.iter)?;
+
+        let flushed = self.write_buf_writable(buf)?;
+        buf.writeln("{")?;
+        buf.writeln("let mut _did_loop = false;")?;
+        match loop_block.iter {
+            Expr::Range(_, _, _) => buf.writeln(&format!("let _iter = {expr_code};")),
+            Expr::Array(..) => buf.writeln(&format!("let _iter = {expr_code}.iter();")),
+            // If `iter` is a call then we assume it's something that returns
+            // an iterator. If not then the user can explicitly add the needed
+            // call without issues.
+            Expr::Call(..) | Expr::Index(..) => {
+                buf.writeln(&format!("let _iter = ({expr_code}).into_iter();"))
+            }
+            // If accessing `self` then it most likely needs to be
+            // borrowed, to prevent an attempt of moving.
+            _ if expr_code.starts_with("self.") => {
+                buf.writeln(&format!("let _iter = (&{expr_code}).into_iter();"))
+            }
+            // If accessing a field then it most likely needs to be
+            // borrowed, to prevent an attempt of moving.
+            Expr::Attr(..) => buf.writeln(&format!("let _iter = (&{expr_code}).into_iter();")),
+            // Otherwise, we borrow `iter` assuming that it implements `IntoIterator`.
+            _ => buf.writeln(&format!("let _iter = ({expr_code}).into_iter();")),
+        }?;
+        if let Some(cond) = &loop_block.cond {
+            self.locals.push();
+            buf.write("let _iter = _iter.filter(|");
+            self.visit_target(buf, true, true, &loop_block.var);
+            buf.write("| -> bool {");
+            self.visit_expr(buf, cond)?;
+            buf.writeln("});")?;
+            self.locals.pop();
+        }
+
+        self.locals.push();
+        buf.write("for (");
+        self.visit_target(buf, true, true, &loop_block.var);
+        buf.writeln(", _loop_item) in ::askama::helpers::TemplateLoop::new(_iter) {")?;
+
+        buf.writeln("_did_loop = true;")?;
+        let mut size_hint1 = self.handle(ctx, &loop_block.body, buf, AstLevel::Nested)?;
+        self.handle_ws(loop_block.ws2);
+        size_hint1 += self.write_buf_writable(buf)?;
+        self.locals.pop();
+        buf.writeln("}")?;
+
+        buf.writeln("if !_did_loop {")?;
+        self.locals.push();
+        let mut size_hint2 = self.handle(ctx, &loop_block.else_block, buf, AstLevel::Nested)?;
+        self.handle_ws(loop_block.ws3);
+        size_hint2 += self.write_buf_writable(buf)?;
+        self.locals.pop();
+        buf.writeln("}")?;
+
+        buf.writeln("}")?;
+
+        Ok(flushed + ((size_hint1 * 3) + size_hint2) / 2)
+    }
+
+    fn write_call(
+        &mut self,
+        ctx: &'a Context<'_>,
+        buf: &mut Buffer,
+        ws: Ws,
+        scope: Option<&str>,
+        name: &str,
+        args: &[Expr<'_>],
+    ) -> Result<usize, CompileError> {
+        if name == "super" {
+            return self.write_block(buf, None, ws);
+        }
+
+        let (def, own_ctx) = match scope {
+            Some(s) => {
+                let path = ctx.imports.get(s).ok_or_else(|| {
+                    CompileError::from(format!("no import found for scope {s:?}"))
+                })?;
+                let mctx = self
+                    .contexts
+                    .get(path.as_path())
+                    .ok_or_else(|| CompileError::from(format!("context for {path:?} not found")))?;
+                let def = mctx.macros.get(name).ok_or_else(|| {
+                    CompileError::from(format!("macro {name:?} not found in scope {s:?}"))
+                })?;
+                (def, mctx)
+            }
+            None => {
+                let def = ctx
+                    .macros
+                    .get(name)
+                    .ok_or_else(|| CompileError::from(format!("macro {name:?} not found")))?;
+                (def, ctx)
+            }
+        };
+
+        self.flush_ws(ws); // Cannot handle_ws() here: whitespace from macro definition comes first
+        self.locals.push();
+        self.write_buf_writable(buf)?;
+        buf.writeln("{")?;
+        self.prepare_ws(def.ws1);
+
+        let mut names = Buffer::new(0);
+        let mut values = Buffer::new(0);
+        let mut is_first_variable = true;
+        for (i, arg) in def.args.iter().enumerate() {
+            let expr = args.get(i).ok_or_else(|| {
+                CompileError::from(format!("macro {name:?} takes more than {i} arguments"))
+            })?;
+
+            match expr {
+                // If `expr` is already a form of variable then
+                // don't reintroduce a new variable. This is
+                // to avoid moving non-copyable values.
+                Expr::Var(name) => {
+                    let var = self.locals.resolve_or_self(name);
+                    self.locals.insert(arg, LocalMeta::with_ref(var));
+                }
+                Expr::Attr(obj, attr) => {
+                    let mut attr_buf = Buffer::new(0);
+                    self.visit_attr(&mut attr_buf, obj, attr)?;
+
+                    let var = self.locals.resolve(&attr_buf.buf).unwrap_or(attr_buf.buf);
+                    self.locals.insert(arg, LocalMeta::with_ref(var));
+                }
+                // Everything else still needs to become variables,
+                // to avoid having the same logic be executed
+                // multiple times, e.g. in the case of macro
+                // parameters being used multiple times.
+                _ => {
+                    if is_first_variable {
+                        is_first_variable = false
+                    } else {
+                        names.write(", ");
+                        values.write(", ");
+                    }
+                    names.write(arg);
+
+                    values.write("(");
+                    values.write(&self.visit_expr_root(expr)?);
+                    values.write(")");
+                    self.locals.insert_with_default(arg);
+                }
+            }
+        }
+
+        debug_assert_eq!(names.buf.is_empty(), values.buf.is_empty());
+        if !names.buf.is_empty() {
+            buf.writeln(&format!("let ({}) = ({});", names.buf, values.buf))?;
+        }
+
+        let mut size_hint = self.handle(own_ctx, &def.nodes, buf, AstLevel::Nested)?;
+
+        self.flush_ws(def.ws2);
+        size_hint += self.write_buf_writable(buf)?;
+        buf.writeln("}")?;
+        self.locals.pop();
+        self.prepare_ws(ws);
+        Ok(size_hint)
+    }
+
+    fn handle_include(
+        &mut self,
+        ctx: &'a Context<'_>,
+        buf: &mut Buffer,
+        ws: Ws,
+        path: &str,
+    ) -> Result<usize, CompileError> {
+        self.flush_ws(ws);
+        self.write_buf_writable(buf)?;
+        let path = self
+            .input
+            .config
+            .find_template(path, Some(&self.input.path))?;
+        let src = get_template_source(&path)?;
+        let nodes = parse(&src, self.input.syntax)?;
+
+        // Make sure the compiler understands that the generated code depends on the template file.
+        {
+            let path = path.to_str().unwrap();
+            buf.writeln(
+                &quote! {
+                    include_bytes!(#path);
+                }
+                .to_string(),
+            )?;
+        }
+
+        let size_hint = {
+            // Since nodes must not outlive the Generator, we instantiate
+            // a nested Generator here to handle the include's nodes.
+            let mut gen = self.child();
+            let mut size_hint = gen.handle(ctx, &nodes, buf, AstLevel::Nested)?;
+            size_hint += gen.write_buf_writable(buf)?;
+            size_hint
+        };
+        self.prepare_ws(ws);
+        Ok(size_hint)
+    }
+
+    fn write_let_decl(
+        &mut self,
+        buf: &mut Buffer,
+        ws: Ws,
+        var: &'a Target<'_>,
+    ) -> Result<(), CompileError> {
+        self.handle_ws(ws);
+        self.write_buf_writable(buf)?;
+        buf.write("let ");
+        self.visit_target(buf, false, true, var);
+        buf.writeln(";")
+    }
+
+    fn is_shadowing_variable(&self, var: &Target<'a>) -> Result<bool, CompileError> {
+        match var {
+            Target::Name(name) => {
+                let name = normalize_identifier(name);
+                match self.locals.get(&name) {
+                    // declares a new variable
+                    None => Ok(false),
+                    // an initialized variable gets shadowed
+                    Some(meta) if meta.initialized => Ok(true),
+                    // initializes a variable that was introduced in a LetDecl before
+                    _ => Ok(false),
+                }
+            }
+            Target::Tuple(_, targets) => {
+                for target in targets {
+                    match self.is_shadowing_variable(target) {
+                        Ok(false) => continue,
+                        outcome => return outcome,
+                    }
+                }
+                Ok(false)
+            }
+            Target::Struct(_, named_targets) => {
+                for (_, target) in named_targets {
+                    match self.is_shadowing_variable(target) {
+                        Ok(false) => continue,
+                        outcome => return outcome,
+                    }
+                }
+                Ok(false)
+            }
+            _ => Err("literals are not allowed on the left-hand side of an assignment".into()),
+        }
+    }
+
+    fn write_let(
+        &mut self,
+        buf: &mut Buffer,
+        ws: Ws,
+        var: &'a Target<'_>,
+        val: &Expr<'_>,
+    ) -> Result<(), CompileError> {
+        self.handle_ws(ws);
+        let mut expr_buf = Buffer::new(0);
+        self.visit_expr(&mut expr_buf, val)?;
+
+        let shadowed = self.is_shadowing_variable(var)?;
+        if shadowed {
+            // Need to flush the buffer if the variable is being shadowed,
+            // to ensure the old variable is used.
+            self.write_buf_writable(buf)?;
+        }
+        if shadowed
+            || !matches!(var, &Target::Name(_))
+            || matches!(var, Target::Name(name) if self.locals.get(name).is_none())
+        {
+            buf.write("let ");
+        }
+
+        self.visit_target(buf, true, true, var);
+        buf.writeln(&format!(" = {};", &expr_buf.buf))
+    }
+
+    // If `name` is `Some`, this is a call to a block definition, and we have to find
+    // the first block for that name from the ancestry chain. If name is `None`, this
+    // is from a `super()` call, and we can get the name from `self.super_block`.
+    fn write_block(
+        &mut self,
+        buf: &mut Buffer,
+        name: Option<&'a str>,
+        outer: Ws,
+    ) -> Result<usize, CompileError> {
+        // Flush preceding whitespace according to the outer WS spec
+        self.flush_ws(outer);
+
+        let prev_block = self.super_block;
+        let cur = match (name, prev_block) {
+            // The top-level context contains a block definition
+            (Some(cur_name), None) => (cur_name, 0),
+            // A block definition contains a block definition of the same name
+            (Some(cur_name), Some((prev_name, _))) if cur_name == prev_name => {
+                return Err(format!("cannot define recursive blocks ({cur_name})").into());
+            }
+            // A block definition contains a definition of another block
+            (Some(cur_name), Some((_, _))) => (cur_name, 0),
+            // `super()` was called inside a block
+            (None, Some((prev_name, gen))) => (prev_name, gen + 1),
+            // `super()` is called from outside a block
+            (None, None) => return Err("cannot call 'super()' outside block".into()),
+        };
+        self.super_block = Some(cur);
+
+        // Get the block definition from the heritage chain
+        let heritage = self
+            .heritage
+            .as_ref()
+            .ok_or_else(|| CompileError::from("no block ancestors available"))?;
+        let (ctx, def) = heritage.blocks[cur.0].get(cur.1).ok_or_else(|| {
+            CompileError::from(match name {
+                None => format!("no super() block found for block '{}'", cur.0),
+                Some(name) => format!("no block found for name '{name}'"),
+            })
+        })?;
+
+        // Get the nodes and whitespace suppression data from the block definition
+        let (ws1, nodes, ws2) = if let Node::BlockDef(ws1, _, nodes, ws2) = def {
+            (ws1, nodes, ws2)
+        } else {
+            unreachable!()
+        };
+
+        // Handle inner whitespace suppression spec and process block nodes
+        self.prepare_ws(*ws1);
+        self.locals.push();
+        let size_hint = self.handle(ctx, nodes, buf, AstLevel::Block)?;
+
+        if !self.locals.is_current_empty() {
+            // Need to flush the buffer before popping the variable stack
+            self.write_buf_writable(buf)?;
+        }
+
+        self.locals.pop();
+        self.flush_ws(*ws2);
+
+        // Restore original block context and set whitespace suppression for
+        // succeeding whitespace according to the outer WS spec
+        self.super_block = prev_block;
+        self.prepare_ws(outer);
+        Ok(size_hint)
+    }
+
+    fn write_expr(&mut self, ws: Ws, s: &'a Expr<'a>) {
+        self.handle_ws(ws);
+        self.buf_writable.push(Writable::Expr(s));
+    }
+
+    // Write expression buffer and empty
+    fn write_buf_writable(&mut self, buf: &mut Buffer) -> Result<usize, CompileError> {
+        if self.buf_writable.is_empty() {
+            return Ok(0);
+        }
+
+        if self
+            .buf_writable
+            .iter()
+            .all(|w| matches!(w, Writable::Lit(_)))
+        {
+            let mut buf_lit = Buffer::new(0);
+            for s in mem::take(&mut self.buf_writable) {
+                if let Writable::Lit(s) = s {
+                    buf_lit.write(s);
+                };
+            }
+            buf.writeln(&format!("writer.write_str({:#?})?;", &buf_lit.buf))?;
+            return Ok(buf_lit.buf.len());
+        }
+
+        let mut size_hint = 0;
+        let mut buf_format = Buffer::new(0);
+        let mut buf_expr = Buffer::new(buf.indent + 1);
+        let mut expr_cache = HashMap::with_capacity(self.buf_writable.len());
+        for s in mem::take(&mut self.buf_writable) {
+            match s {
+                Writable::Lit(s) => {
+                    buf_format.write(&s.replace('{', "{{").replace('}', "}}"));
+                    size_hint += s.len();
+                }
+                Writable::Expr(s) => {
+                    use self::DisplayWrap::*;
+                    let mut expr_buf = Buffer::new(0);
+                    let wrapped = self.visit_expr(&mut expr_buf, s)?;
+                    let expression = match wrapped {
+                        Wrapped => expr_buf.buf,
+                        Unwrapped => format!(
+                            "::askama::MarkupDisplay::new_unsafe(&({}), {})",
+                            expr_buf.buf, self.input.escaper
+                        ),
+                    };
+
+                    let id = match expr_cache.entry(expression.clone()) {
+                        Entry::Occupied(e) if s.is_cacheable() => *e.get(),
+                        e => {
+                            let id = self.named;
+                            self.named += 1;
+
+                            buf_expr.write(&format!("expr{id} = "));
+                            buf_expr.write("&");
+                            buf_expr.write(&expression);
+                            buf_expr.writeln(",")?;
+
+                            if let Entry::Vacant(e) = e {
+                                e.insert(id);
+                            }
+
+                            id
+                        }
+                    };
+
+                    buf_format.write(&format!("{{expr{id}}}"));
+                    size_hint += 3;
+                }
+            }
+        }
+
+        buf.writeln("::std::write!(")?;
+        buf.indent();
+        buf.writeln("writer,")?;
+        buf.writeln(&format!("{:#?},", &buf_format.buf))?;
+        buf.writeln(buf_expr.buf.trim())?;
+        buf.dedent()?;
+        buf.writeln(")?;")?;
+        Ok(size_hint)
+    }
+
+    fn visit_lit(&mut self, lws: &'a str, val: &'a str, rws: &'a str) {
+        assert!(self.next_ws.is_none());
+        if !lws.is_empty() {
+            match self.skip_ws {
+                WhitespaceHandling::Suppress => {}
+                _ if val.is_empty() => {
+                    assert!(rws.is_empty());
+                    self.next_ws = Some(lws);
+                }
+                WhitespaceHandling::Preserve => self.buf_writable.push(Writable::Lit(lws)),
+                WhitespaceHandling::Minimize => {
+                    self.buf_writable
+                        .push(Writable::Lit(match lws.contains('\n') {
+                            true => "\n",
+                            false => " ",
+                        }));
+                }
+            }
+        }
+
+        if !val.is_empty() {
+            self.skip_ws = WhitespaceHandling::Preserve;
+            self.buf_writable.push(Writable::Lit(val));
+        }
+
+        if !rws.is_empty() {
+            self.next_ws = Some(rws);
+        }
+    }
+
+    fn write_comment(&mut self, ws: Ws) {
+        self.handle_ws(ws);
+    }
+
+    /* Visitor methods for expression types */
+
+    fn visit_expr_root(&mut self, expr: &Expr<'_>) -> Result<String, CompileError> {
+        let mut buf = Buffer::new(0);
+        self.visit_expr(&mut buf, expr)?;
+        Ok(buf.buf)
+    }
+
+    fn visit_expr(
+        &mut self,
+        buf: &mut Buffer,
+        expr: &Expr<'_>,
+    ) -> Result<DisplayWrap, CompileError> {
+        Ok(match *expr {
+            Expr::BoolLit(s) => self.visit_bool_lit(buf, s),
+            Expr::NumLit(s) => self.visit_num_lit(buf, s),
+            Expr::StrLit(s) => self.visit_str_lit(buf, s),
+            Expr::CharLit(s) => self.visit_char_lit(buf, s),
+            Expr::Var(s) => self.visit_var(buf, s),
+            Expr::Path(ref path) => self.visit_path(buf, path),
+            Expr::Array(ref elements) => self.visit_array(buf, elements)?,
+            Expr::Attr(ref obj, name) => self.visit_attr(buf, obj, name)?,
+            Expr::Index(ref obj, ref key) => self.visit_index(buf, obj, key)?,
+            Expr::Filter(name, ref args) => self.visit_filter(buf, name, args)?,
+            Expr::Unary(op, ref inner) => self.visit_unary(buf, op, inner)?,
+            Expr::BinOp(op, ref left, ref right) => self.visit_binop(buf, op, left, right)?,
+            Expr::Range(op, ref left, ref right) => {
+                self.visit_range(buf, op, left.as_deref(), right.as_deref())?
+            }
+            Expr::Group(ref inner) => self.visit_group(buf, inner)?,
+            Expr::Call(ref obj, ref args) => self.visit_call(buf, obj, args)?,
+            Expr::RustMacro(name, args) => self.visit_rust_macro(buf, name, args),
+            Expr::Try(ref expr) => self.visit_try(buf, expr.as_ref())?,
+            Expr::Tuple(ref exprs) => self.visit_tuple(buf, exprs)?,
+        })
+    }
+
+    fn visit_try(
+        &mut self,
+        buf: &mut Buffer,
+        expr: &Expr<'_>,
+    ) -> Result<DisplayWrap, CompileError> {
+        buf.write("::core::result::Result::map_err(");
+        self.visit_expr(buf, expr)?;
+        buf.write(", |err| ::askama::shared::Error::Custom(::core::convert::Into::into(err)))?");
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_rust_macro(&mut self, buf: &mut Buffer, name: &str, args: &str) -> DisplayWrap {
+        buf.write(name);
+        buf.write("!(");
+        buf.write(args);
+        buf.write(")");
+
+        DisplayWrap::Unwrapped
+    }
+
+    #[cfg(not(feature = "markdown"))]
+    fn _visit_markdown_filter(
+        &mut self,
+        _buf: &mut Buffer,
+        _args: &[Expr<'_>],
+    ) -> Result<DisplayWrap, CompileError> {
+        Err("the `markdown` filter requires the `markdown` feature to be enabled".into())
+    }
+
+    #[cfg(feature = "markdown")]
+    fn _visit_markdown_filter(
+        &mut self,
+        buf: &mut Buffer,
+        args: &[Expr<'_>],
+    ) -> Result<DisplayWrap, CompileError> {
+        let (md, options) = match args {
+            [md] => (md, None),
+            [md, options] => (md, Some(options)),
+            _ => return Err("markdown filter expects no more than one option argument".into()),
+        };
+
+        buf.write(&format!(
+            "::askama::filters::markdown({}, ",
+            self.input.escaper
+        ));
+        self.visit_expr(buf, md)?;
+        match options {
+            Some(options) => {
+                buf.write(", ::core::option::Option::Some(");
+                self.visit_expr(buf, options)?;
+                buf.write(")");
+            }
+            None => buf.write(", ::core::option::Option::None"),
+        }
+        buf.write(")?");
+
+        Ok(DisplayWrap::Wrapped)
+    }
+
+    fn visit_filter(
+        &mut self,
+        buf: &mut Buffer,
+        mut name: &str,
+        args: &[Expr<'_>],
+    ) -> Result<DisplayWrap, CompileError> {
+        if matches!(name, "escape" | "e") {
+            self._visit_escape_filter(buf, args)?;
+            return Ok(DisplayWrap::Wrapped);
+        } else if name == "format" {
+            self._visit_format_filter(buf, args)?;
+            return Ok(DisplayWrap::Unwrapped);
+        } else if name == "fmt" {
+            self._visit_fmt_filter(buf, args)?;
+            return Ok(DisplayWrap::Unwrapped);
+        } else if name == "join" {
+            self._visit_join_filter(buf, args)?;
+            return Ok(DisplayWrap::Unwrapped);
+        } else if name == "markdown" {
+            return self._visit_markdown_filter(buf, args);
+        }
+
+        if name == "tojson" {
+            name = "json";
+        }
+
+        #[cfg(not(feature = "serde-json"))]
+        if name == "json" {
+            return Err("the `json` filter requires the `serde-json` feature to be enabled".into());
+        }
+        #[cfg(not(feature = "serde-yaml"))]
+        if name == "yaml" {
+            return Err("the `yaml` filter requires the `serde-yaml` feature to be enabled".into());
+        }
+
+        const FILTERS: [&str; 2] = ["safe", "yaml"];
+        if FILTERS.contains(&name) {
+            buf.write(&format!(
+                "::askama::filters::{}({}, ",
+                name, self.input.escaper
+            ));
+        } else if crate::BUILT_IN_FILTERS.contains(&name) {
+            buf.write(&format!("::askama::filters::{name}("));
+        } else {
+            buf.write(&format!("filters::{name}("));
+        }
+
+        self._visit_args(buf, args)?;
+        buf.write(")?");
+        Ok(match FILTERS.contains(&name) {
+            true => DisplayWrap::Wrapped,
+            false => DisplayWrap::Unwrapped,
+        })
+    }
+
+    fn _visit_escape_filter(
+        &mut self,
+        buf: &mut Buffer,
+        args: &[Expr<'_>],
+    ) -> Result<(), CompileError> {
+        if args.len() > 2 {
+            return Err("only two arguments allowed to escape filter".into());
+        }
+        let opt_escaper = match args.get(1) {
+            Some(Expr::StrLit(name)) => Some(*name),
+            Some(_) => return Err("invalid escaper type for escape filter".into()),
+            None => None,
+        };
+        let escaper = match opt_escaper {
+            Some(name) => self
+                .input
+                .config
+                .escapers
+                .iter()
+                .find_map(|(escapers, escaper)| escapers.contains(name).then_some(escaper))
+                .ok_or_else(|| CompileError::from("invalid escaper for escape filter"))?,
+            None => self.input.escaper,
+        };
+        buf.write("::askama::filters::escape(");
+        buf.write(escaper);
+        buf.write(", ");
+        self._visit_args(buf, &args[..1])?;
+        buf.write(")?");
+        Ok(())
+    }
+
+    fn _visit_format_filter(
+        &mut self,
+        buf: &mut Buffer,
+        args: &[Expr<'_>],
+    ) -> Result<(), CompileError> {
+        buf.write("format!(");
+        if let Some(Expr::StrLit(v)) = args.first() {
+            self.visit_str_lit(buf, v);
+            if args.len() > 1 {
+                buf.write(", ");
+            }
+        } else {
+            return Err("invalid expression type for format filter".into());
+        }
+        self._visit_args(buf, &args[1..])?;
+        buf.write(")");
+        Ok(())
+    }
+
+    fn _visit_fmt_filter(
+        &mut self,
+        buf: &mut Buffer,
+        args: &[Expr<'_>],
+    ) -> Result<(), CompileError> {
+        buf.write("format!(");
+        if let Some(Expr::StrLit(v)) = args.get(1) {
+            self.visit_str_lit(buf, v);
+            buf.write(", ");
+        } else {
+            return Err("invalid expression type for fmt filter".into());
+        }
+        self._visit_args(buf, &args[0..1])?;
+        if args.len() > 2 {
+            return Err("only two arguments allowed to fmt filter".into());
+        }
+        buf.write(")");
+        Ok(())
+    }
+
+    // Force type coercion on first argument to `join` filter (see #39).
+    fn _visit_join_filter(
+        &mut self,
+        buf: &mut Buffer,
+        args: &[Expr<'_>],
+    ) -> Result<(), CompileError> {
+        buf.write("::askama::filters::join((&");
+        for (i, arg) in args.iter().enumerate() {
+            if i > 0 {
+                buf.write(", &");
+            }
+            self.visit_expr(buf, arg)?;
+            if i == 0 {
+                buf.write(").into_iter()");
+            }
+        }
+        buf.write(")?");
+        Ok(())
+    }
+
+    fn _visit_args(&mut self, buf: &mut Buffer, args: &[Expr<'_>]) -> Result<(), CompileError> {
+        if args.is_empty() {
+            return Ok(());
+        }
+
+        for (i, arg) in args.iter().enumerate() {
+            if i > 0 {
+                buf.write(", ");
+            }
+
+            let borrow = !arg.is_copyable();
+            if borrow {
+                buf.write("&(");
+            }
+
+            match arg {
+                Expr::Call(left, _) if !matches!(left.as_ref(), Expr::Path(_)) => {
+                    buf.writeln("{")?;
+                    self.visit_expr(buf, arg)?;
+                    buf.writeln("}")?;
+                }
+                _ => {
+                    self.visit_expr(buf, arg)?;
+                }
+            }
+
+            if borrow {
+                buf.write(")");
+            }
+        }
+        Ok(())
+    }
+
+    fn visit_attr(
+        &mut self,
+        buf: &mut Buffer,
+        obj: &Expr<'_>,
+        attr: &str,
+    ) -> Result<DisplayWrap, CompileError> {
+        if let Expr::Var(name) = *obj {
+            if name == "loop" {
+                if attr == "index" {
+                    buf.write("(_loop_item.index + 1)");
+                    return Ok(DisplayWrap::Unwrapped);
+                } else if attr == "index0" {
+                    buf.write("_loop_item.index");
+                    return Ok(DisplayWrap::Unwrapped);
+                } else if attr == "first" {
+                    buf.write("_loop_item.first");
+                    return Ok(DisplayWrap::Unwrapped);
+                } else if attr == "last" {
+                    buf.write("_loop_item.last");
+                    return Ok(DisplayWrap::Unwrapped);
+                } else {
+                    return Err("unknown loop variable".into());
+                }
+            }
+        }
+        self.visit_expr(buf, obj)?;
+        buf.write(&format!(".{}", normalize_identifier(attr)));
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_index(
+        &mut self,
+        buf: &mut Buffer,
+        obj: &Expr<'_>,
+        key: &Expr<'_>,
+    ) -> Result<DisplayWrap, CompileError> {
+        buf.write("&");
+        self.visit_expr(buf, obj)?;
+        buf.write("[");
+        self.visit_expr(buf, key)?;
+        buf.write("]");
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_call(
+        &mut self,
+        buf: &mut Buffer,
+        left: &Expr<'_>,
+        args: &[Expr<'_>],
+    ) -> Result<DisplayWrap, CompileError> {
+        match left {
+            Expr::Attr(left, method) if **left == Expr::Var("loop") => match *method {
+                "cycle" => match args {
+                    [arg] => {
+                        if matches!(arg, Expr::Array(arr) if arr.is_empty()) {
+                            return Err("loop.cycle(…) cannot use an empty array".into());
+                        }
+                        buf.write("({");
+                        buf.write("let _cycle = &(");
+                        self.visit_expr(buf, arg)?;
+                        buf.writeln(");")?;
+                        buf.writeln("let _len = _cycle.len();")?;
+                        buf.writeln("if _len == 0 {")?;
+                        buf.writeln("return ::core::result::Result::Err(::askama::Error::Fmt(::core::fmt::Error));")?;
+                        buf.writeln("}")?;
+                        buf.writeln("_cycle[_loop_item.index % _len]")?;
+                        buf.writeln("})")?;
+                    }
+                    _ => return Err("loop.cycle(…) expects exactly one argument".into()),
+                },
+                s => return Err(format!("unknown loop method: {s:?}").into()),
+            },
+            left => {
+                match left {
+                    Expr::Var(name) => match self.locals.resolve(name) {
+                        Some(resolved) => buf.write(&resolved),
+                        None => buf.write(&format!("(&self.{})", normalize_identifier(name))),
+                    },
+                    left => {
+                        self.visit_expr(buf, left)?;
+                    }
+                }
+
+                buf.write("(");
+                self._visit_args(buf, args)?;
+                buf.write(")");
+            }
+        }
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_unary(
+        &mut self,
+        buf: &mut Buffer,
+        op: &str,
+        inner: &Expr<'_>,
+    ) -> Result<DisplayWrap, CompileError> {
+        buf.write(op);
+        self.visit_expr(buf, inner)?;
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_range(
+        &mut self,
+        buf: &mut Buffer,
+        op: &str,
+        left: Option<&Expr<'_>>,
+        right: Option<&Expr<'_>>,
+    ) -> Result<DisplayWrap, CompileError> {
+        if let Some(left) = left {
+            self.visit_expr(buf, left)?;
+        }
+        buf.write(op);
+        if let Some(right) = right {
+            self.visit_expr(buf, right)?;
+        }
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_binop(
+        &mut self,
+        buf: &mut Buffer,
+        op: &str,
+        left: &Expr<'_>,
+        right: &Expr<'_>,
+    ) -> Result<DisplayWrap, CompileError> {
+        self.visit_expr(buf, left)?;
+        buf.write(&format!(" {op} "));
+        self.visit_expr(buf, right)?;
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_group(
+        &mut self,
+        buf: &mut Buffer,
+        inner: &Expr<'_>,
+    ) -> Result<DisplayWrap, CompileError> {
+        buf.write("(");
+        self.visit_expr(buf, inner)?;
+        buf.write(")");
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_tuple(
+        &mut self,
+        buf: &mut Buffer,
+        exprs: &[Expr<'_>],
+    ) -> Result<DisplayWrap, CompileError> {
+        buf.write("(");
+        for (index, expr) in exprs.iter().enumerate() {
+            if index > 0 {
+                buf.write(" ");
+            }
+            self.visit_expr(buf, expr)?;
+            buf.write(",");
+        }
+        buf.write(")");
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_array(
+        &mut self,
+        buf: &mut Buffer,
+        elements: &[Expr<'_>],
+    ) -> Result<DisplayWrap, CompileError> {
+        buf.write("[");
+        for (i, el) in elements.iter().enumerate() {
+            if i > 0 {
+                buf.write(", ");
+            }
+            self.visit_expr(buf, el)?;
+        }
+        buf.write("]");
+        Ok(DisplayWrap::Unwrapped)
+    }
+
+    fn visit_path(&mut self, buf: &mut Buffer, path: &[&str]) -> DisplayWrap {
+        for (i, part) in path.iter().enumerate() {
+            if i > 0 {
+                buf.write("::");
+            }
+            buf.write(part);
+        }
+        DisplayWrap::Unwrapped
+    }
+
+    fn visit_var(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
+        if s == "self" {
+            buf.write(s);
+            return DisplayWrap::Unwrapped;
+        }
+
+        buf.write(normalize_identifier(&self.locals.resolve_or_self(s)));
+        DisplayWrap::Unwrapped
+    }
+
+    fn visit_bool_lit(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
+        buf.write(s);
+        DisplayWrap::Unwrapped
+    }
+
+    fn visit_str_lit(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
+        buf.write(&format!("\"{s}\""));
+        DisplayWrap::Unwrapped
+    }
+
+    fn visit_char_lit(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
+        buf.write(&format!("'{s}'"));
+        DisplayWrap::Unwrapped
+    }
+
+    fn visit_num_lit(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
+        buf.write(s);
+        DisplayWrap::Unwrapped
+    }
+
+    fn visit_target(
+        &mut self,
+        buf: &mut Buffer,
+        initialized: bool,
+        first_level: bool,
+        target: &Target<'a>,
+    ) {
+        match target {
+            Target::Name("_") => {
+                buf.write("_");
+            }
+            Target::Name(name) => {
+                let name = normalize_identifier(name);
+                match initialized {
+                    true => self.locals.insert(name, LocalMeta::initialized()),
+                    false => self.locals.insert_with_default(name),
+                }
+                buf.write(name);
+            }
+            Target::Tuple(path, targets) => {
+                buf.write(&path.join("::"));
+                buf.write("(");
+                for target in targets {
+                    self.visit_target(buf, initialized, false, target);
+                    buf.write(",");
+                }
+                buf.write(")");
+            }
+            Target::Struct(path, targets) => {
+                buf.write(&path.join("::"));
+                buf.write(" { ");
+                for (name, target) in targets {
+                    buf.write(normalize_identifier(name));
+                    buf.write(": ");
+                    self.visit_target(buf, initialized, false, target);
+                    buf.write(",");
+                }
+                buf.write(" }");
+            }
+            Target::Path(path) => {
+                self.visit_path(buf, path);
+            }
+            Target::StrLit(s) => {
+                if first_level {
+                    buf.write("&");
+                }
+                self.visit_str_lit(buf, s);
+            }
+            Target::NumLit(s) => {
+                if first_level {
+                    buf.write("&");
+                }
+                self.visit_num_lit(buf, s);
+            }
+            Target::CharLit(s) => {
+                if first_level {
+                    buf.write("&");
+                }
+                self.visit_char_lit(buf, s);
+            }
+            Target::BoolLit(s) => {
+                if first_level {
+                    buf.write("&");
+                }
+                buf.write(s);
+            }
+        }
+    }
+
+    /* Helper methods for dealing with whitespace nodes */
+
+    // Combines `flush_ws()` and `prepare_ws()` to handle both trailing whitespace from the
+    // preceding literal and leading whitespace from the succeeding literal.
+    fn handle_ws(&mut self, ws: Ws) {
+        self.flush_ws(ws);
+        self.prepare_ws(ws);
+    }
+
+    fn should_trim_ws(&self, ws: Option<Whitespace>) -> WhitespaceHandling {
+        match ws {
+            Some(Whitespace::Suppress) => WhitespaceHandling::Suppress,
+            Some(Whitespace::Preserve) => WhitespaceHandling::Preserve,
+            Some(Whitespace::Minimize) => WhitespaceHandling::Minimize,
+            None => self.whitespace,
+        }
+    }
+
+    // If the previous literal left some trailing whitespace in `next_ws` and the
+    // prefix whitespace suppressor from the given argument, flush that whitespace.
+    // In either case, `next_ws` is reset to `None` (no trailing whitespace).
+    fn flush_ws(&mut self, ws: Ws) {
+        if self.next_ws.is_none() {
+            return;
+        }
+
+        // If `whitespace` is set to `suppress`, we keep the whitespace characters only if there is
+        // a `+` character.
+        match self.should_trim_ws(ws.0) {
+            WhitespaceHandling::Preserve => {
+                let val = self.next_ws.unwrap();
+                if !val.is_empty() {
+                    self.buf_writable.push(Writable::Lit(val));
+                }
+            }
+            WhitespaceHandling::Minimize => {
+                let val = self.next_ws.unwrap();
+                if !val.is_empty() {
+                    self.buf_writable
+                        .push(Writable::Lit(match val.contains('\n') {
+                            true => "\n",
+                            false => " ",
+                        }));
+                }
+            }
+            WhitespaceHandling::Suppress => {}
+        }
+        self.next_ws = None;
+    }
+
+    // Sets `skip_ws` to match the suffix whitespace suppressor from the given
+    // argument, to determine whether to suppress leading whitespace from the
+    // next literal.
+    fn prepare_ws(&mut self, ws: Ws) {
+        self.skip_ws = self.should_trim_ws(ws.1);
+    }
+}
+
+struct Buffer {
+    // The buffer to generate the code into
+    buf: String,
+    // The current level of indentation (in spaces)
+    indent: u8,
+    // Whether the output buffer is currently at the start of a line
+    start: bool,
+}
+
+impl Buffer {
+    fn new(indent: u8) -> Self {
+        Self {
+            buf: String::new(),
+            indent,
+            start: true,
+        }
+    }
+
+    fn writeln(&mut self, s: &str) -> Result<(), CompileError> {
+        if s == "}" {
+            self.dedent()?;
+        }
+        if !s.is_empty() {
+            self.write(s);
+        }
+        self.buf.push('\n');
+        if s.ends_with('{') {
+            self.indent();
+        }
+        self.start = true;
+        Ok(())
+    }
+
+    fn write(&mut self, s: &str) {
+        if self.start {
+            for _ in 0..(self.indent * 4) {
+                self.buf.push(' ');
+            }
+            self.start = false;
+        }
+        self.buf.push_str(s);
+    }
+
+    fn indent(&mut self) {
+        self.indent += 1;
+    }
+
+    fn dedent(&mut self) -> Result<(), CompileError> {
+        if self.indent == 0 {
+            return Err("dedent() called while indentation == 0".into());
+        }
+        self.indent -= 1;
+        Ok(())
+    }
+}
+
+#[derive(Clone, Default)]
+struct LocalMeta {
+    refs: Option<String>,
+    initialized: bool,
+}
+
+impl LocalMeta {
+    fn initialized() -> Self {
+        Self {
+            refs: None,
+            initialized: true,
+        }
+    }
+
+    fn with_ref(refs: String) -> Self {
+        Self {
+            refs: Some(refs),
+            initialized: true,
+        }
+    }
+}
+
+// type SetChain<'a, T> = MapChain<'a, T, ()>;
+
+#[derive(Debug)]
+struct MapChain<'a, K, V>
+where
+    K: cmp::Eq + hash::Hash,
+{
+    parent: Option<&'a MapChain<'a, K, V>>,
+    scopes: Vec<HashMap<K, V>>,
+}
+
+impl<'a, K: 'a, V: 'a> MapChain<'a, K, V>
+where
+    K: cmp::Eq + hash::Hash,
+{
+    fn new() -> MapChain<'a, K, V> {
+        MapChain {
+            parent: None,
+            scopes: vec![HashMap::new()],
+        }
+    }
+
+    fn with_parent<'p>(parent: &'p MapChain<'_, K, V>) -> MapChain<'p, K, V> {
+        MapChain {
+            parent: Some(parent),
+            scopes: vec![HashMap::new()],
+        }
+    }
+
+    /// Iterates the scopes in reverse and returns `Some(LocalMeta)`
+    /// from the first scope where `key` exists.
+    fn get(&self, key: &K) -> Option<&V> {
+        let mut scopes = self.scopes.iter().rev();
+        scopes
+            .find_map(|set| set.get(key))
+            .or_else(|| self.parent.and_then(|set| set.get(key)))
+    }
+
+    fn is_current_empty(&self) -> bool {
+        self.scopes.last().unwrap().is_empty()
+    }
+
+    fn insert(&mut self, key: K, val: V) {
+        self.scopes.last_mut().unwrap().insert(key, val);
+
+        // Note that if `insert` returns `Some` then it implies
+        // an identifier is reused. For e.g. `{% macro f(a, a) %}`
+        // and `{% let (a, a) = ... %}` then this results in a
+        // generated template, which when compiled fails with the
+        // compile error "identifier `a` used more than once".
+    }
+
+    fn insert_with_default(&mut self, key: K)
+    where
+        V: Default,
+    {
+        self.insert(key, V::default());
+    }
+
+    fn push(&mut self) {
+        self.scopes.push(HashMap::new());
+    }
+
+    fn pop(&mut self) {
+        self.scopes.pop().unwrap();
+        assert!(!self.scopes.is_empty());
+    }
+}
+
+impl MapChain<'_, &str, LocalMeta> {
+    fn resolve(&self, name: &str) -> Option<String> {
+        let name = normalize_identifier(name);
+        self.get(&name).map(|meta| match &meta.refs {
+            Some(expr) => expr.clone(),
+            None => name.to_string(),
+        })
+    }
+
+    fn resolve_or_self(&self, name: &str) -> String {
+        let name = normalize_identifier(name);
+        self.resolve(name).unwrap_or_else(|| format!("self.{name}"))
+    }
+}
+
+fn median(sizes: &mut [usize]) -> usize {
+    sizes.sort_unstable();
+    if sizes.len() % 2 == 1 {
+        sizes[sizes.len() / 2]
+    } else {
+        (sizes[sizes.len() / 2 - 1] + sizes[sizes.len() / 2]) / 2
+    }
+}
+
+#[derive(Clone, Copy, PartialEq)]
+enum AstLevel {
+    Top,
+    Block,
+    Nested,
+}
+
+#[derive(Clone, Copy)]
+enum DisplayWrap {
+    Wrapped,
+    Unwrapped,
+}
+
+#[derive(Debug)]
+enum Writable<'a> {
+    Lit(&'a str),
+    Expr(&'a Expr<'a>),
+}
+
+// Identifiers to be replaced with raw identifiers, so as to avoid
+// collisions between template syntax and Rust's syntax. In particular
+// [Rust keywords](https://doc.rust-lang.org/reference/keywords.html)
+// should be replaced, since they're not reserved words in Askama
+// syntax but have a high probability of causing problems in the
+// generated code.
+//
+// This list excludes the Rust keywords *self*, *Self*, and *super*
+// because they are not allowed to be raw identifiers, and *loop*
+// because it's used something like a keyword in the template
+// language.
+static USE_RAW: [(&str, &str); 47] = [
+    ("as", "r#as"),
+    ("break", "r#break"),
+    ("const", "r#const"),
+    ("continue", "r#continue"),
+    ("crate", "r#crate"),
+    ("else", "r#else"),
+    ("enum", "r#enum"),
+    ("extern", "r#extern"),
+    ("false", "r#false"),
+    ("fn", "r#fn"),
+    ("for", "r#for"),
+    ("if", "r#if"),
+    ("impl", "r#impl"),
+    ("in", "r#in"),
+    ("let", "r#let"),
+    ("match", "r#match"),
+    ("mod", "r#mod"),
+    ("move", "r#move"),
+    ("mut", "r#mut"),
+    ("pub", "r#pub"),
+    ("ref", "r#ref"),
+    ("return", "r#return"),
+    ("static", "r#static"),
+    ("struct", "r#struct"),
+    ("trait", "r#trait"),
+    ("true", "r#true"),
+    ("type", "r#type"),
+    ("unsafe", "r#unsafe"),
+    ("use", "r#use"),
+    ("where", "r#where"),
+    ("while", "r#while"),
+    ("async", "r#async"),
+    ("await", "r#await"),
+    ("dyn", "r#dyn"),
+    ("abstract", "r#abstract"),
+    ("become", "r#become"),
+    ("box", "r#box"),
+    ("do", "r#do"),
+    ("final", "r#final"),
+    ("macro", "r#macro"),
+    ("override", "r#override"),
+    ("priv", "r#priv"),
+    ("typeof", "r#typeof"),
+    ("unsized", "r#unsized"),
+    ("virtual", "r#virtual"),
+    ("yield", "r#yield"),
+    ("try", "r#try"),
+];
+
+fn normalize_identifier(ident: &str) -> &str {
+    if let Some(word) = USE_RAW.iter().find(|x| x.0 == ident) {
+        word.1
+    } else {
+        ident
+    }
+}
diff --git a/third_party/rust/askama_derive/src/heritage.rs b/third_party/rust/askama_derive/src/heritage.rs
new file mode 100644
index 0000000000..dbb2b1fa00
--- /dev/null
+++ b/third_party/rust/askama_derive/src/heritage.rs
@@ -0,0 +1,126 @@
+use std::collections::HashMap;
+use std::path::{Path, PathBuf};
+
+use crate::config::Config;
+use crate::parser::{Loop, Macro, Node};
+use crate::CompileError;
+
+pub(crate) struct Heritage<'a> {
+    pub(crate) root: &'a Context<'a>,
+    pub(crate) blocks: BlockAncestry<'a>,
+}
+
+impl Heritage<'_> {
+    pub(crate) fn new<'n>(
+        mut ctx: &'n Context<'n>,
+        contexts: &'n HashMap<&'n Path, Context<'n>>,
+    ) -> Heritage<'n> {
+        let mut blocks: BlockAncestry<'n> = ctx
+            .blocks
+            .iter()
+            .map(|(name, def)| (*name, vec![(ctx, *def)]))
+            .collect();
+
+        while let Some(ref path) = ctx.extends {
+            ctx = &contexts[path.as_path()];
+            for (name, def) in &ctx.blocks {
+                blocks.entry(name).or_insert_with(Vec::new).push((ctx, def));
+            }
+        }
+
+        Heritage { root: ctx, blocks }
+    }
+}
+
+type BlockAncestry<'a> = HashMap<&'a str, Vec<(&'a Context<'a>, &'a Node<'a>)>>;
+
+pub(crate) struct Context<'a> {
+    pub(crate) nodes: &'a [Node<'a>],
+    pub(crate) extends: Option<PathBuf>,
+    pub(crate) blocks: HashMap<&'a str, &'a Node<'a>>,
+    pub(crate) macros: HashMap<&'a str, &'a Macro<'a>>,
+    pub(crate) imports: HashMap<&'a str, PathBuf>,
+}
+
+impl Context<'_> {
+    pub(crate) fn new<'n>(
+        config: &Config<'_>,
+        path: &Path,
+        nodes: &'n [Node<'n>],
+    ) -> Result<Context<'n>, CompileError> {
+        let mut extends = None;
+        let mut blocks = Vec::new();
+        let mut macros = HashMap::new();
+        let mut imports = HashMap::new();
+        let mut nested = vec![nodes];
+        let mut top = true;
+
+        while let Some(nodes) = nested.pop() {
+            for n in nodes {
+                match n {
+                    Node::Extends(extends_path) if top => match extends {
+                        Some(_) => return Err("multiple extend blocks found".into()),
+                        None => {
+                            extends = Some(config.find_template(extends_path, Some(path))?);
+                        }
+                    },
+                    Node::Macro(name, m) if top => {
+                        macros.insert(*name, m);
+                    }
+                    Node::Import(_, import_path, scope) if top => {
+                        let path = config.find_template(import_path, Some(path))?;
+                        imports.insert(*scope, path);
+                    }
+                    Node::Extends(_) | Node::Macro(_, _) | Node::Import(_, _, _) if !top => {
+                        return Err(
+                            "extends, macro or import blocks not allowed below top level".into(),
+                        );
+                    }
+                    def @ Node::BlockDef(_, _, _, _) => {
+                        blocks.push(def);
+                        if let Node::BlockDef(_, _, nodes, _) = def {
+                            nested.push(nodes);
+                        }
+                    }
+                    Node::Cond(branches, _) => {
+                        for (_, _, nodes) in branches {
+                            nested.push(nodes);
+                        }
+                    }
+                    Node::Loop(Loop {
+                        body, else_block, ..
+                    }) => {
+                        nested.push(body);
+                        nested.push(else_block);
+                    }
+                    Node::Match(_, _, arms, _) => {
+                        for (_, _, arm) in arms {
+                            nested.push(arm);
+                        }
+                    }
+                    _ => {}
+                }
+            }
+            top = false;
+        }
+
+        let blocks: HashMap<_, _> = blocks
+            .iter()
+            .map(|def| {
+                if let Node::BlockDef(_, name, _, _) = def {
+                    (*name, *def)
+                } else {
+                    unreachable!()
+                }
+            })
+            .collect();
+
+        Ok(Context {
+            nodes,
+            extends,
+            blocks,
+            macros,
+            imports,
+        })
+    }
+}
diff --git a/third_party/rust/askama_derive/src/input.rs b/third_party/rust/askama_derive/src/input.rs
new file mode 100644
index 0000000000..47d51bd891
--- /dev/null
+++ b/third_party/rust/askama_derive/src/input.rs
@@ -0,0 +1,231 @@
+use crate::config::{Config, Syntax};
+use crate::generator::TemplateArgs;
+use crate::CompileError;
+
+use std::path::{Path, PathBuf};
+use std::str::FromStr;
+
+use mime::Mime;
+
+pub(crate) struct TemplateInput<'a> {
+    pub(crate) ast: &'a syn::DeriveInput,
+    pub(crate) config: &'a Config<'a>,
+    pub(crate) syntax: &'a Syntax<'a>,
+    pub(crate) source: Source,
+    pub(crate) print: Print,
+    pub(crate) escaper: &'a str,
+    pub(crate) ext: Option<String>,
+    pub(crate) mime_type: String,
+    pub(crate) path: PathBuf,
+}
+
+impl TemplateInput<'_> {
+    /// Extract the template metadata from the `DeriveInput` structure. This
+    /// mostly recovers the data for the `TemplateInput` fields from the
+    /// `template()` attribute list fields.
+    pub(crate) fn new<'n>(
+        ast: &'n syn::DeriveInput,
+        config: &'n Config<'_>,
+        args: TemplateArgs,
+    ) -> Result<TemplateInput<'n>, CompileError> {
+        let TemplateArgs {
+            source,
+            print,
+            escaping,
+            ext,
+            syntax,
+            ..
+        } = args;
+
+        // Validate the `source` and `ext` value together, since they are
+        // related. In case `source` was used instead of `path`, the value
+        // of `ext` is merged into a synthetic `path` value here.
+        let source = source.expect("template path or source not found in attributes");
+        let path = match (&source, &ext) {
+            (Source::Path(path), _) => config.find_template(path, None)?,
+            (&Source::Source(_), Some(ext)) => PathBuf::from(format!("{}.{}", ast.ident, ext)),
+            (&Source::Source(_), None) => {
+                return Err("must include 'ext' attribute when using 'source' attribute".into())
+            }
+        };
+
+        // Validate syntax
+        let syntax = syntax.map_or_else(
+            || Ok(config.syntaxes.get(config.default_syntax).unwrap()),
+            |s| {
+                config
+                    .syntaxes
+                    .get(&s)
+                    .ok_or_else(|| CompileError::from(format!("attribute syntax {s} not exist")))
+            },
+        )?;
+
+        // Match extension against defined output formats
+
+        let escaping = escaping.unwrap_or_else(|| {
+            path.extension()
+                .map(|s| s.to_str().unwrap())
+                .unwrap_or("")
+                .to_string()
+        });
+
+        let mut escaper = None;
+        for (extensions, path) in &config.escapers {
+            if extensions.contains(&escaping) {
+                escaper = Some(path);
+                break;
+            }
+        }
+
+        let escaper = escaper.ok_or_else(|| {
+            CompileError::from(format!("no escaper defined for extension '{escaping}'"))
+        })?;
+
+        let mime_type =
+            extension_to_mime_type(ext_default_to_path(ext.as_deref(), &path).unwrap_or("txt"))
+                .to_string();
+
+        Ok(TemplateInput {
+            ast,
+            config,
+            syntax,
+            source,
+            print,
+            escaper,
+            ext,
+            mime_type,
+            path,
+        })
+    }
+
+    #[inline]
+    pub(crate) fn extension(&self) -> Option<&str> {
+        ext_default_to_path(self.ext.as_deref(), &self.path)
+    }
+}
+
+#[inline]
+fn ext_default_to_path<'a>(ext: Option<&'a str>, path: &'a Path) -> Option<&'a str> {
+    ext.or_else(|| extension(path))
+}
+
+fn extension(path: &Path) -> Option<&str> {
+    let ext = path.extension().map(|s| s.to_str().unwrap())?;
+
+    const JINJA_EXTENSIONS: [&str; 3] = ["j2", "jinja", "jinja2"];
+    if JINJA_EXTENSIONS.contains(&ext) {
+        Path::new(path.file_stem().unwrap())
+            .extension()
+            .map(|s| s.to_str().unwrap())
+            .or(Some(ext))
+    } else {
+        Some(ext)
+    }
+}
+
+pub(crate) enum Source {
+    Path(String),
+    Source(String),
+}
+
+#[derive(PartialEq)]
+pub(crate) enum Print {
+    All,
+    Ast,
+    Code,
+    None,
+}
+
+impl FromStr for Print {
+    type Err = CompileError;
+
+    fn from_str(s: &str) -> Result<Print, Self::Err> {
+        use self::Print::*;
+        Ok(match s {
+            "all" => All,
+            "ast" => Ast,
+            "code" => Code,
+            "none" => None,
+            v => return Err(format!("invalid value for print option: {v}",).into()),
+        })
+    }
+}
+
+impl Default for Print {
+    fn default() -> Self {
+        Self::None
+    }
+}
+
+pub(crate) fn extension_to_mime_type(ext: &str) -> Mime {
+    let basic_type = mime_guess::from_ext(ext).first_or_octet_stream();
+    for (simple, utf_8) in &TEXT_TYPES {
+        if &basic_type == simple {
+            return utf_8.clone();
+        }
+    }
+    basic_type
+}
+
+const TEXT_TYPES: [(Mime, Mime); 6] = [
+    (mime::TEXT_PLAIN, mime::TEXT_PLAIN_UTF_8),
+    (mime::TEXT_HTML, mime::TEXT_HTML_UTF_8),
+    (mime::TEXT_CSS, mime::TEXT_CSS_UTF_8),
+    (mime::TEXT_CSV, mime::TEXT_CSV_UTF_8),
+    (
+        mime::TEXT_TAB_SEPARATED_VALUES,
+        mime::TEXT_TAB_SEPARATED_VALUES_UTF_8,
+    ),
+    (
+        mime::APPLICATION_JAVASCRIPT,
+        mime::APPLICATION_JAVASCRIPT_UTF_8,
+    ),
+];
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_ext() {
+        assert_eq!(extension(Path::new("foo-bar.txt")), Some("txt"));
+        assert_eq!(extension(Path::new("foo-bar.html")), Some("html"));
+        assert_eq!(extension(Path::new("foo-bar.unknown")), Some("unknown"));
+
+        assert_eq!(extension(Path::new("foo/bar/baz.txt")), Some("txt"));
+        assert_eq!(extension(Path::new("foo/bar/baz.html")), Some("html"));
+        assert_eq!(extension(Path::new("foo/bar/baz.unknown")), Some("unknown"));
+    }
+
+    #[test]
+    fn test_double_ext() {
+        assert_eq!(extension(Path::new("foo-bar.html.txt")), Some("txt"));
+        assert_eq!(extension(Path::new("foo-bar.txt.html")), Some("html"));
+        assert_eq!(extension(Path::new("foo-bar.txt.unknown")), Some("unknown"));
+
+        assert_eq!(extension(Path::new("foo/bar/baz.html.txt")), Some("txt"));
+        assert_eq!(extension(Path::new("foo/bar/baz.txt.html")), Some("html"));
+        assert_eq!(
+            extension(Path::new("foo/bar/baz.txt.unknown")),
+            Some("unknown")
+        );
+    }
+
+    #[test]
+    fn test_skip_jinja_ext() {
+        assert_eq!(extension(Path::new("foo-bar.html.j2")), Some("html"));
+        assert_eq!(extension(Path::new("foo-bar.html.jinja")), Some("html"));
+        assert_eq!(extension(Path::new("foo-bar.html.jinja2")), Some("html"));
+
+        assert_eq!(extension(Path::new("foo/bar/baz.txt.j2")), Some("txt"));
+        assert_eq!(extension(Path::new("foo/bar/baz.txt.jinja")), Some("txt"));
+        assert_eq!(extension(Path::new("foo/bar/baz.txt.jinja2")), Some("txt"));
+    }
+
+    #[test]
+    fn test_only_jinja_ext() {
+        assert_eq!(extension(Path::new("foo-bar.j2")), Some("j2"));
+        assert_eq!(extension(Path::new("foo-bar.jinja")), Some("jinja"));
+        assert_eq!(extension(Path::new("foo-bar.jinja2")), Some("jinja2"));
+    }
+}
diff --git a/third_party/rust/askama_derive/src/lib.rs b/third_party/rust/askama_derive/src/lib.rs
new file mode 100644
index 0000000000..2acf58380b
--- /dev/null
+++ b/third_party/rust/askama_derive/src/lib.rs
@@ -0,0 +1,100 @@
+#![forbid(unsafe_code)]
+#![deny(elided_lifetimes_in_paths)]
+#![deny(unreachable_pub)]
+
+use std::borrow::Cow;
+use std::fmt;
+
+use proc_macro::TokenStream;
+use proc_macro2::Span;
+
+mod config;
+mod generator;
+mod heritage;
+mod input;
+mod parser;
+
+#[proc_macro_derive(Template, attributes(template))]
+pub fn derive_template(input: TokenStream) -> TokenStream {
+    generator::derive_template(input)
+}
+
+#[derive(Debug, Clone)]
+struct CompileError {
+    msg: Cow<'static, str>,
+    span: Span,
+}
+
+impl CompileError {
+    fn new<S: Into<Cow<'static, str>>>(s: S, span: Span) -> Self {
+        Self {
+            msg: s.into(),
+            span,
+        }
+    }
+
+    fn into_compile_error(self) -> TokenStream {
+        syn::Error::new(self.span, self.msg)
+            .to_compile_error()
+            .into()
+    }
+}
+
+impl std::error::Error for CompileError {}
+
+impl fmt::Display for CompileError {
+    #[inline]
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.write_str(&self.msg)
+    }
+}
+
+impl From<&'static str> for CompileError {
+    #[inline]
+    fn from(s: &'static str) -> Self {
+        Self::new(s, Span::call_site())
+    }
+}
+
+impl From<String> for CompileError {
+    #[inline]
+    fn from(s: String) -> Self {
+        Self::new(s, Span::call_site())
+    }
+}
+
+// This is used by the code generator to decide whether a named filter is part of
+// Askama or should refer to a local `filters` module. It should contain all the
+// filters shipped with Askama, even the optional ones (since optional inclusion
+// in the const vector based on features seems impossible right now).
+const BUILT_IN_FILTERS: &[&str] = &[
+    "abs",
+    "capitalize",
+    "center",
+    "e",
+    "escape",
+    "filesizeformat",
+    "fmt",
+    "format",
+    "indent",
+    "into_f64",
+    "into_isize",
+    "join",
+    "linebreaks",
+    "linebreaksbr",
+    "paragraphbreaks",
+    "lower",
+    "lowercase",
+    "safe",
+    "trim",
+    "truncate",
+    "upper",
+    "uppercase",
+    "urlencode",
+    "urlencode_strict",
+    "wordcount",
+    // optional features, reserve the names anyway:
+    "json",
+    "markdown",
+    "yaml",
+];
diff --git a/third_party/rust/askama_derive/src/parser/expr.rs b/third_party/rust/askama_derive/src/parser/expr.rs
new file mode 100644
index 0000000000..fabaa34cc4
--- /dev/null
+++ b/third_party/rust/askama_derive/src/parser/expr.rs
@@ -0,0 +1,346 @@
+use std::str;
+
+use nom::branch::alt;
+use nom::bytes::complete::{tag, take_till};
+use nom::character::complete::char;
+use nom::combinator::{cut, map, not, opt, peek, recognize};
+use nom::multi::{fold_many0, many0, separated_list0, separated_list1};
+use nom::sequence::{delimited, pair, preceded, terminated, tuple};
+use nom::IResult;
+
+use super::{
+    bool_lit, char_lit, identifier, nested_parenthesis, not_ws, num_lit, path, str_lit, ws,
+};
+
+#[derive(Debug, PartialEq)]
+pub(crate) enum Expr<'a> {
+    BoolLit(&'a str),
+    NumLit(&'a str),
+    StrLit(&'a str),
+    CharLit(&'a str),
+    Var(&'a str),
+    Path(Vec<&'a str>),
+    Array(Vec<Expr<'a>>),
+    Attr(Box<Expr<'a>>, &'a str),
+    Index(Box<Expr<'a>>, Box<Expr<'a>>),
+    Filter(&'a str, Vec<Expr<'a>>),
+    Unary(&'a str, Box<Expr<'a>>),
+    BinOp(&'a str, Box<Expr<'a>>, Box<Expr<'a>>),
+    Range(&'a str, Option<Box<Expr<'a>>>, Option<Box<Expr<'a>>>),
+    Group(Box<Expr<'a>>),
+    Tuple(Vec<Expr<'a>>),
+    Call(Box<Expr<'a>>, Vec<Expr<'a>>),
+    RustMacro(&'a str, &'a str),
+    Try(Box<Expr<'a>>),
+}
+
+impl Expr<'_> {
+    pub(super) fn parse(i: &str) -> IResult<&str, Expr<'_>> {
+        expr_any(i)
+    }
+
+    pub(super) fn parse_arguments(i: &str) -> IResult<&str, Vec<Expr<'_>>> {
+        arguments(i)
+    }
+
+    /// Returns `true` if enough assumptions can be made,
+    /// to determine that `self` is copyable.
+    pub(crate) fn is_copyable(&self) -> bool {
+        self.is_copyable_within_op(false)
+    }
+
+    fn is_copyable_within_op(&self, within_op: bool) -> bool {
+        use Expr::*;
+        match self {
+            BoolLit(_) | NumLit(_) | StrLit(_) | CharLit(_) => true,
+            Unary(.., expr) => expr.is_copyable_within_op(true),
+            BinOp(_, lhs, rhs) => {
+                lhs.is_copyable_within_op(true) && rhs.is_copyable_within_op(true)
+            }
+            Range(..) => true,
+            // The result of a call likely doesn't need to be borrowed,
+            // as in that case the call is more likely to return a
+            // reference in the first place then.
+            Call(..) | Path(..) => true,
+            // If the `expr` is within a `Unary` or `BinOp` then
+            // an assumption can be made that the operand is copy.
+            // If not, then the value is moved and adding `.clone()`
+            // will solve that issue. However, if the operand is
+            // implicitly borrowed, then it's likely not even possible
+            // to get the template to compile.
+            _ => within_op && self.is_attr_self(),
+        }
+    }
+
+    /// Returns `true` if this is an `Attr` where the `obj` is `"self"`.
+    pub(crate) fn is_attr_self(&self) -> bool {
+        match self {
+            Expr::Attr(obj, _) if matches!(obj.as_ref(), Expr::Var("self")) => true,
+            Expr::Attr(obj, _) if matches!(obj.as_ref(), Expr::Attr(..)) => obj.is_attr_self(),
+            _ => false,
+        }
+    }
+
+    /// Returns `true` if the outcome of this expression may be used multiple times in the same
+    /// `write!()` call, without evaluating the expression again, i.e. the expression should be
+    /// side-effect free.
+    pub(crate) fn is_cacheable(&self) -> bool {
+        match self {
+            // Literals are the definition of pure:
+            Expr::BoolLit(_) => true,
+            Expr::NumLit(_) => true,
+            Expr::StrLit(_) => true,
+            Expr::CharLit(_) => true,
+            // fmt::Display should have no effects:
+            Expr::Var(_) => true,
+            Expr::Path(_) => true,
+            // Check recursively:
+            Expr::Array(args) => args.iter().all(|arg| arg.is_cacheable()),
+            Expr::Attr(lhs, _) => lhs.is_cacheable(),
+            Expr::Index(lhs, rhs) => lhs.is_cacheable() && rhs.is_cacheable(),
+            Expr::Filter(_, args) => args.iter().all(|arg| arg.is_cacheable()),
+            Expr::Unary(_, arg) => arg.is_cacheable(),
+            Expr::BinOp(_, lhs, rhs) => lhs.is_cacheable() && rhs.is_cacheable(),
+            Expr::Range(_, lhs, rhs) => {
+                lhs.as_ref().map_or(true, |v| v.is_cacheable())
+                    && rhs.as_ref().map_or(true, |v| v.is_cacheable())
+            }
+            Expr::Group(arg) => arg.is_cacheable(),
+            Expr::Tuple(args) => args.iter().all(|arg| arg.is_cacheable()),
+            // We have too little information to tell if the expression is pure:
+            Expr::Call(_, _) => false,
+            Expr::RustMacro(_, _) => false,
+            Expr::Try(_) => false,
+        }
+    }
+}
+
+fn expr_bool_lit(i: &str) -> IResult<&str, Expr<'_>> {
+    map(bool_lit, Expr::BoolLit)(i)
+}
+
+fn expr_num_lit(i: &str) -> IResult<&str, Expr<'_>> {
+    map(num_lit, Expr::NumLit)(i)
+}
+
+fn expr_array_lit(i: &str) -> IResult<&str, Expr<'_>> {
+    delimited(
+        ws(char('[')),
+        map(separated_list1(ws(char(',')), expr_any), Expr::Array),
+        ws(char(']')),
+    )(i)
+}
+
+fn expr_str_lit(i: &str) -> IResult<&str, Expr<'_>> {
+    map(str_lit, Expr::StrLit)(i)
+}
+
+fn expr_char_lit(i: &str) -> IResult<&str, Expr<'_>> {
+    map(char_lit, Expr::CharLit)(i)
+}
+
+fn expr_var(i: &str) -> IResult<&str, Expr<'_>> {
+    map(identifier, Expr::Var)(i)
+}
+
+fn expr_path(i: &str) -> IResult<&str, Expr<'_>> {
+    let (i, path) = path(i)?;
+    Ok((i, Expr::Path(path)))
+}
+
+fn expr_group(i: &str) -> IResult<&str, Expr<'_>> {
+    let (i, expr) = preceded(ws(char('(')), opt(expr_any))(i)?;
+    let expr = match expr {
+        Some(expr) => expr,
+        None => {
+            let (i, _) = char(')')(i)?;
+            return Ok((i, Expr::Tuple(vec![])));
+        }
+    };
+
+    let (i, comma) = ws(opt(peek(char(','))))(i)?;
+    if comma.is_none() {
+        let (i, _) = char(')')(i)?;
+        return Ok((i, Expr::Group(Box::new(expr))));
+    }
+
+    let mut exprs = vec![expr];
+    let (i, _) = fold_many0(
+        preceded(char(','), ws(expr_any)),
+        || (),
+        |_, expr| {
+            exprs.push(expr);
+        },
+    )(i)?;
+    let (i, _) = pair(ws(opt(char(','))), char(')'))(i)?;
+    Ok((i, Expr::Tuple(exprs)))
+}
+
+fn expr_single(i: &str) -> IResult<&str, Expr<'_>> {
+    alt((
+        expr_bool_lit,
+        expr_num_lit,
+        expr_str_lit,
+        expr_char_lit,
+        expr_path,
+        expr_rust_macro,
+        expr_array_lit,
+        expr_var,
+        expr_group,
+    ))(i)
+}
+
+enum Suffix<'a> {
+    Attr(&'a str),
+    Index(Expr<'a>),
+    Call(Vec<Expr<'a>>),
+    Try,
+}
+
+fn expr_attr(i: &str) -> IResult<&str, Suffix<'_>> {
+    map(
+        preceded(
+            ws(pair(char('.'), not(char('.')))),
+            cut(alt((num_lit, identifier))),
+        ),
+        Suffix::Attr,
+    )(i)
+}
+
+fn expr_index(i: &str) -> IResult<&str, Suffix<'_>> {
+    map(
+        preceded(ws(char('[')), cut(terminated(expr_any, ws(char(']'))))),
+        Suffix::Index,
+    )(i)
+}
+
+fn expr_call(i: &str) -> IResult<&str, Suffix<'_>> {
+    map(arguments, Suffix::Call)(i)
+}
+
+fn expr_try(i: &str) -> IResult<&str, Suffix<'_>> {
+    map(preceded(take_till(not_ws), char('?')), |_| Suffix::Try)(i)
+}
+
+fn filter(i: &str) -> IResult<&str, (&str, Option<Vec<Expr<'_>>>)> {
+    let (i, (_, fname, args)) = tuple((char('|'), ws(identifier), opt(arguments)))(i)?;
+    Ok((i, (fname, args)))
+}
+
+fn expr_filtered(i: &str) -> IResult<&str, Expr<'_>> {
+    let (i, (obj, filters)) = tuple((expr_prefix, many0(filter)))(i)?;
+
+    let mut res = obj;
+    for (fname, args) in filters {
+        res = Expr::Filter(fname, {
+            let mut args = match args {
+                Some(inner) => inner,
+                None => Vec::new(),
+            };
+            args.insert(0, res);
+            args
+        });
+    }
+
+    Ok((i, res))
+}
+
+fn expr_prefix(i: &str) -> IResult<&str, Expr<'_>> {
+    let (i, (ops, mut expr)) = pair(many0(ws(alt((tag("!"), tag("-"))))), expr_suffix)(i)?;
+    for op in ops.iter().rev() {
+        expr = Expr::Unary(op, Box::new(expr));
+    }
+    Ok((i, expr))
+}
+
+fn expr_suffix(i: &str) -> IResult<&str, Expr<'_>> {
+    let (mut i, mut expr) = expr_single(i)?;
+    loop {
+        let (j, suffix) = opt(alt((expr_attr, expr_index, expr_call, expr_try)))(i)?;
+        i = j;
+        match suffix {
+            Some(Suffix::Attr(attr)) => expr = Expr::Attr(expr.into(), attr),
+            Some(Suffix::Index(index)) => expr = Expr::Index(expr.into(), index.into()),
+            Some(Suffix::Call(args)) => expr = Expr::Call(expr.into(), args),
+            Some(Suffix::Try) => expr = Expr::Try(expr.into()),
+            None => break,
+        }
+    }
+    Ok((i, expr))
+}
+
+fn macro_arguments(i: &str) -> IResult<&str, &str> {
+    delimited(char('('), recognize(nested_parenthesis), char(')'))(i)
+}
+
+fn expr_rust_macro(i: &str) -> IResult<&str, Expr<'_>> {
+    let (i, (mname, _, args)) = tuple((identifier, char('!'), macro_arguments))(i)?;
+    Ok((i, Expr::RustMacro(mname, args)))
+}
+
+macro_rules! expr_prec_layer {
+    ( $name:ident, $inner:ident, $op:expr ) => {
+        fn $name(i: &str) -> IResult<&str, Expr<'_>> {
+            let (i, left) = $inner(i)?;
+            let (i, right) = many0(pair(
+                ws(tag($op)),
+                $inner,
+            ))(i)?;
+            Ok((
+                i,
+                right.into_iter().fold(left, |left, (op, right)| {
+                    Expr::BinOp(op, Box::new(left), Box::new(right))
+                }),
+            ))
+        }
+    };
+    ( $name:ident, $inner:ident, $( $op:expr ),+ ) => {
+        fn $name(i: &str) -> IResult<&str, Expr<'_>> {
+            let (i, left) = $inner(i)?;
+            let (i, right) = many0(pair(
+                ws(alt(($( tag($op) ),+,))),
+                $inner,
+            ))(i)?;
+            Ok((
+                i,
+                right.into_iter().fold(left, |left, (op, right)| {
+                    Expr::BinOp(op, Box::new(left), Box::new(right))
+                }),
+            ))
+        }
+    }
+}
+
+expr_prec_layer!(expr_muldivmod, expr_filtered, "*", "/", "%");
+expr_prec_layer!(expr_addsub, expr_muldivmod, "+", "-");
+expr_prec_layer!(expr_shifts, expr_addsub, ">>", "<<");
+expr_prec_layer!(expr_band, expr_shifts, "&");
+expr_prec_layer!(expr_bxor, expr_band, "^");
+expr_prec_layer!(expr_bor, expr_bxor, "|");
+expr_prec_layer!(expr_compare, expr_bor, "==", "!=", ">=", ">", "<=", "<");
+expr_prec_layer!(expr_and, expr_compare, "&&");
+expr_prec_layer!(expr_or, expr_and, "||");
+
+fn expr_any(i: &str) -> IResult<&str, Expr<'_>> {
+    let range_right = |i| pair(ws(alt((tag("..="), tag("..")))), opt(expr_or))(i);
+    alt((
+        map(range_right, |(op, right)| {
+            Expr::Range(op, None, right.map(Box::new))
+        }),
+        map(
+            pair(expr_or, opt(range_right)),
+            |(left, right)| match right {
+                Some((op, right)) => Expr::Range(op, Some(Box::new(left)), right.map(Box::new)),
+                None => left,
+            },
+        ),
+    ))(i)
+}
+
+fn arguments(i: &str) -> IResult<&str, Vec<Expr<'_>>> {
+    delimited(
+        ws(char('(')),
+        separated_list0(char(','), ws(expr_any)),
+        ws(char(')')),
+    )(i)
+}
diff --git a/third_party/rust/askama_derive/src/parser/mod.rs b/third_party/rust/askama_derive/src/parser/mod.rs
new file mode 100644
index 0000000000..79b178ef85
--- /dev/null
+++ b/third_party/rust/askama_derive/src/parser/mod.rs
@@ -0,0 +1,317 @@
+use std::cell::Cell;
+use std::str;
+
+use nom::branch::alt;
+use nom::bytes::complete::{escaped, is_not, tag, take_till};
+use nom::character::complete::char;
+use nom::character::complete::{anychar, digit1};
+use nom::combinator::{eof, map, not, opt, recognize, value};
+use nom::error::ErrorKind;
+use nom::multi::separated_list1;
+use nom::sequence::{delimited, pair, tuple};
+use nom::{error_position, AsChar, IResult, InputTakeAtPosition};
+
+pub(crate) use self::expr::Expr;
+pub(crate) use self::node::{Cond, CondTest, Loop, Macro, Node, Target, When, Whitespace, Ws};
+use crate::config::Syntax;
+use crate::CompileError;
+
+mod expr;
+mod node;
+#[cfg(test)]
+mod tests;
+
+struct State<'a> {
+    syntax: &'a Syntax<'a>,
+    loop_depth: Cell<usize>,
+}
+
+impl<'a> State<'a> {
+    fn new(syntax: &'a Syntax<'a>) -> State<'a> {
+        State {
+            syntax,
+            loop_depth: Cell::new(0),
+        }
+    }
+
+    fn enter_loop(&self) {
+        self.loop_depth.set(self.loop_depth.get() + 1);
+    }
+
+    fn leave_loop(&self) {
+        self.loop_depth.set(self.loop_depth.get() - 1);
+    }
+
+    fn is_in_loop(&self) -> bool {
+        self.loop_depth.get() > 0
+    }
+}
+
+impl From<char> for Whitespace {
+    fn from(c: char) -> Self {
+        match c {
+            '+' => Self::Preserve,
+            '-' => Self::Suppress,
+            '~' => Self::Minimize,
+            _ => panic!("unsupported `Whitespace` conversion"),
+        }
+    }
+}
+
+pub(crate) fn parse<'a>(
+    src: &'a str,
+    syntax: &'a Syntax<'_>,
+) -> Result<Vec<Node<'a>>, CompileError> {
+    match Node::parse(src, &State::new(syntax)) {
+        Ok((left, res)) => {
+            if !left.is_empty() {
+                Err(format!("unable to parse template:\n\n{left:?}").into())
+            } else {
+                Ok(res)
+            }
+        }
+
+        Err(nom::Err::Error(err)) | Err(nom::Err::Failure(err)) => {
+            let nom::error::Error { input, .. } = err;
+            let offset = src.len() - input.len();
+            let (source_before, source_after) = src.split_at(offset);
+
+            let source_after = match source_after.char_indices().enumerate().take(41).last() {
+                Some((40, (i, _))) => format!("{:?}...", &source_after[..i]),
+                _ => format!("{source_after:?}"),
+            };
+
+            let (row, last_line) = source_before.lines().enumerate().last().unwrap();
+            let column = last_line.chars().count();
+
+            let msg = format!(
+                "problems parsing template source at row {}, column {} near:\n{}",
+                row + 1,
+                column,
+                source_after,
+            );
+            Err(msg.into())
+        }
+
+        Err(nom::Err::Incomplete(_)) => Err("parsing incomplete".into()),
+    }
+}
+
+fn is_ws(c: char) -> bool {
+    matches!(c, ' ' | '\t' | '\r' | '\n')
+}
+
+fn not_ws(c: char) -> bool {
+    !is_ws(c)
+}
+
+fn ws<'a, O>(
+    inner: impl FnMut(&'a str) -> IResult<&'a str, O>,
+) -> impl FnMut(&'a str) -> IResult<&'a str, O> {
+    delimited(take_till(not_ws), inner, take_till(not_ws))
+}
+
+fn split_ws_parts(s: &str) -> Node<'_> {
+    let trimmed_start = s.trim_start_matches(is_ws);
+    let len_start = s.len() - trimmed_start.len();
+    let trimmed = trimmed_start.trim_end_matches(is_ws);
+    Node::Lit(&s[..len_start], trimmed, &trimmed_start[trimmed.len()..])
+}
+
+/// Skips input until `end` was found, but does not consume it.
+/// Returns tuple that would be returned when parsing `end`.
+fn skip_till<'a, O>(
+    end: impl FnMut(&'a str) -> IResult<&'a str, O>,
+) -> impl FnMut(&'a str) -> IResult<&'a str, (&'a str, O)> {
+    enum Next<O> {
+        IsEnd(O),
+        NotEnd(char),
+    }
+    let mut next = alt((map(end, Next::IsEnd), map(anychar, Next::NotEnd)));
+    move |start: &'a str| {
+        let mut i = start;
+        loop {
+            let (j, is_end) = next(i)?;
+            match is_end {
+                Next::IsEnd(lookahead) => return Ok((i, (j, lookahead))),
+                Next::NotEnd(_) => i = j,
+            }
+        }
+    }
+}
+
+fn keyword<'a>(k: &'a str) -> impl FnMut(&'a str) -> IResult<&'a str, &'a str> {
+    move |i: &'a str| -> IResult<&'a str, &'a str> {
+        let (j, v) = identifier(i)?;
+        if k == v {
+            Ok((j, v))
+        } else {
+            Err(nom::Err::Error(error_position!(i, ErrorKind::Tag)))
+        }
+    }
+}
+
+fn identifier(input: &str) -> IResult<&str, &str> {
+    recognize(pair(identifier_start, opt(identifier_tail)))(input)
+}
+
+fn identifier_start(s: &str) -> IResult<&str, &str> {
+    s.split_at_position1_complete(
+        |c| !(c.is_alpha() || c == '_' || c >= '\u{0080}'),
+        nom::error::ErrorKind::Alpha,
+    )
+}
+
+fn identifier_tail(s: &str) -> IResult<&str, &str> {
+    s.split_at_position1_complete(
+        |c| !(c.is_alphanum() || c == '_' || c >= '\u{0080}'),
+        nom::error::ErrorKind::Alpha,
+    )
+}
+
+fn bool_lit(i: &str) -> IResult<&str, &str> {
+    alt((keyword("false"), keyword("true")))(i)
+}
+
+fn num_lit(i: &str) -> IResult<&str, &str> {
+    recognize(pair(digit1, opt(pair(char('.'), digit1))))(i)
+}
+
+fn str_lit(i: &str) -> IResult<&str, &str> {
+    let (i, s) = delimited(
+        char('"'),
+        opt(escaped(is_not("\\\""), '\\', anychar)),
+        char('"'),
+    )(i)?;
+    Ok((i, s.unwrap_or_default()))
+}
+
+fn char_lit(i: &str) -> IResult<&str, &str> {
+    let (i, s) = delimited(
+        char('\''),
+        opt(escaped(is_not("\\\'"), '\\', anychar)),
+        char('\''),
+    )(i)?;
+    Ok((i, s.unwrap_or_default()))
+}
+
+fn nested_parenthesis(i: &str) -> IResult<&str, ()> {
+    let mut nested = 0;
+    let mut last = 0;
+    let mut in_str = false;
+    let mut escaped = false;
+
+    for (i, b) in i.chars().enumerate() {
+        if !(b == '(' || b == ')') || !in_str {
+            match b {
+                '(' => nested += 1,
+                ')' => {
+                    if nested == 0 {
+                        last = i;
+                        break;
+                    }
+                    nested -= 1;
+                }
+                '"' => {
+                    if in_str {
+                        if !escaped {
+                            in_str = false;
+                        }
+                    } else {
+                        in_str = true;
+                    }
+                }
+                '\\' => {
+                    escaped = !escaped;
+                }
+                _ => (),
+            }
+        }
+
+        if escaped && b != '\\' {
+            escaped = false;
+        }
+    }
+
+    if nested == 0 {
+        Ok((&i[last..], ()))
+    } else {
+        Err(nom::Err::Error(error_position!(
+            i,
+            ErrorKind::SeparatedNonEmptyList
+        )))
+    }
+}
+
+fn path(i: &str) -> IResult<&str, Vec<&str>> {
+    let root = opt(value("", ws(tag("::"))));
+    let tail = separated_list1(ws(tag("::")), identifier);
+
+    match tuple((root, identifier, ws(tag("::")), tail))(i) {
+        Ok((i, (root, start, _, rest))) => {
+            let mut path = Vec::new();
+            path.extend(root);
+            path.push(start);
+            path.extend(rest);
+            Ok((i, path))
+        }
+        Err(err) => {
+            if let Ok((i, name)) = identifier(i) {
+                // The returned identifier can be assumed to be path if:
+                // - Contains both a lowercase and uppercase character, i.e. a type name like `None`
+                // - Doesn't contain any lowercase characters, i.e. it's a constant
+                // In short, if it contains any uppercase characters it's a path.
+                if name.contains(char::is_uppercase) {
+                    return Ok((i, vec![name]));
+                }
+            }
+
+            // If `identifier()` fails then just return the original error
+            Err(err)
+        }
+    }
+}
+
+fn take_content<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let p_start = alt((
+        tag(s.syntax.block_start),
+        tag(s.syntax.comment_start),
+        tag(s.syntax.expr_start),
+    ));
+
+    let (i, _) = not(eof)(i)?;
+    let (i, content) = opt(recognize(skip_till(p_start)))(i)?;
+    let (i, content) = match content {
+        Some("") => {
+            // {block,comment,expr}_start follows immediately.
+            return Err(nom::Err::Error(error_position!(i, ErrorKind::TakeUntil)));
+        }
+        Some(content) => (i, content),
+        None => ("", i), // there is no {block,comment,expr}_start: take everything
+    };
+    Ok((i, split_ws_parts(content)))
+}
+
+fn tag_block_start<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    tag(s.syntax.block_start)(i)
+}
+
+fn tag_block_end<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    tag(s.syntax.block_end)(i)
+}
+
+fn tag_comment_start<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    tag(s.syntax.comment_start)(i)
+}
+
+fn tag_comment_end<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    tag(s.syntax.comment_end)(i)
+}
+
+fn tag_expr_start<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    tag(s.syntax.expr_start)(i)
+}
+
+fn tag_expr_end<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    tag(s.syntax.expr_end)(i)
+}
diff --git a/third_party/rust/askama_derive/src/parser/node.rs b/third_party/rust/askama_derive/src/parser/node.rs
new file mode 100644
index 0000000000..fc6860ef8c
--- /dev/null
+++ b/third_party/rust/askama_derive/src/parser/node.rs
@@ -0,0 +1,682 @@
+use std::str;
+
+use nom::branch::alt;
+use nom::bytes::complete::{tag, take_until};
+use nom::character::complete::char;
+use nom::combinator::{complete, consumed, cut, map, opt, peek, value};
+use nom::error::{Error, ErrorKind};
+use nom::multi::{fold_many0, many0, many1, separated_list0, separated_list1};
+use nom::sequence::{delimited, pair, preceded, terminated, tuple};
+use nom::{error_position, IResult};
+
+use super::{
+    bool_lit, char_lit, identifier, keyword, num_lit, path, skip_till, split_ws_parts, str_lit,
+    tag_block_end, tag_block_start, tag_comment_end, tag_comment_start, tag_expr_end,
+    tag_expr_start, take_content, ws, Expr, State,
+};
+use crate::config::WhitespaceHandling;
+
+#[derive(Debug, PartialEq)]
+pub(crate) enum Node<'a> {
+    Lit(&'a str, &'a str, &'a str),
+    Comment(Ws),
+    Expr(Ws, Expr<'a>),
+    Call(Ws, Option<&'a str>, &'a str, Vec<Expr<'a>>),
+    LetDecl(Ws, Target<'a>),
+    Let(Ws, Target<'a>, Expr<'a>),
+    Cond(Vec<Cond<'a>>, Ws),
+    Match(Ws, Expr<'a>, Vec<When<'a>>, Ws),
+    Loop(Loop<'a>),
+    Extends(&'a str),
+    BlockDef(Ws, &'a str, Vec<Node<'a>>, Ws),
+    Include(Ws, &'a str),
+    Import(Ws, &'a str, &'a str),
+    Macro(&'a str, Macro<'a>),
+    Raw(Ws, &'a str, &'a str, &'a str, Ws),
+    Break(Ws),
+    Continue(Ws),
+}
+
+#[derive(Debug, PartialEq)]
+pub(crate) enum Target<'a> {
+    Name(&'a str),
+    Tuple(Vec<&'a str>, Vec<Target<'a>>),
+    Struct(Vec<&'a str>, Vec<(&'a str, Target<'a>)>),
+    NumLit(&'a str),
+    StrLit(&'a str),
+    CharLit(&'a str),
+    BoolLit(&'a str),
+    Path(Vec<&'a str>),
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub(crate) enum Whitespace {
+    Preserve,
+    Suppress,
+    Minimize,
+}
+
+impl From<WhitespaceHandling> for Whitespace {
+    fn from(ws: WhitespaceHandling) -> Self {
+        match ws {
+            WhitespaceHandling::Suppress => Whitespace::Suppress,
+            WhitespaceHandling::Preserve => Whitespace::Preserve,
+            WhitespaceHandling::Minimize => Whitespace::Minimize,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq)]
+pub(crate) struct Loop<'a> {
+    pub(crate) ws1: Ws,
+    pub(crate) var: Target<'a>,
+    pub(crate) iter: Expr<'a>,
+    pub(crate) cond: Option<Expr<'a>>,
+    pub(crate) body: Vec<Node<'a>>,
+    pub(crate) ws2: Ws,
+    pub(crate) else_block: Vec<Node<'a>>,
+    pub(crate) ws3: Ws,
+}
+
+pub(crate) type When<'a> = (Ws, Target<'a>, Vec<Node<'a>>);
+
+#[derive(Debug, PartialEq)]
+pub(crate) struct Macro<'a> {
+    pub(crate) ws1: Ws,
+    pub(crate) args: Vec<&'a str>,
+    pub(crate) nodes: Vec<Node<'a>>,
+    pub(crate) ws2: Ws,
+}
+
+/// First field is "minus/plus sign was used on the left part of the item".
+///
+/// Second field is "minus/plus sign was used on the right part of the item".
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub(crate) struct Ws(pub(crate) Option<Whitespace>, pub(crate) Option<Whitespace>);
+
+pub(crate) type Cond<'a> = (Ws, Option<CondTest<'a>>, Vec<Node<'a>>);
+
+#[derive(Debug, PartialEq)]
+pub(crate) struct CondTest<'a> {
+    pub(crate) target: Option<Target<'a>>,
+    pub(crate) expr: Expr<'a>,
+}
+
+impl Node<'_> {
+    pub(super) fn parse<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Vec<Node<'a>>> {
+        parse_template(i, s)
+    }
+}
+
+impl Target<'_> {
+    pub(super) fn parse(i: &str) -> IResult<&str, Target<'_>> {
+        target(i)
+    }
+}
+
+fn expr_handle_ws(i: &str) -> IResult<&str, Whitespace> {
+    alt((char('-'), char('+'), char('~')))(i).map(|(s, r)| (s, Whitespace::from(r)))
+}
+
+fn parameters(i: &str) -> IResult<&str, Vec<&str>> {
+    delimited(
+        ws(char('(')),
+        separated_list0(char(','), ws(identifier)),
+        ws(char(')')),
+    )(i)
+}
+
+fn block_call(i: &str) -> IResult<&str, Node<'_>> {
+    let mut p = tuple((
+        opt(expr_handle_ws),
+        ws(keyword("call")),
+        cut(tuple((
+            opt(tuple((ws(identifier), ws(tag("::"))))),
+            ws(identifier),
+            ws(Expr::parse_arguments),
+            opt(expr_handle_ws),
+        ))),
+    ));
+    let (i, (pws, _, (scope, name, args, nws))) = p(i)?;
+    let scope = scope.map(|(scope, _)| scope);
+    Ok((i, Node::Call(Ws(pws, nws), scope, name, args)))
+}
+
+fn cond_if(i: &str) -> IResult<&str, CondTest<'_>> {
+    let mut p = preceded(
+        ws(keyword("if")),
+        cut(tuple((
+            opt(delimited(
+                ws(alt((keyword("let"), keyword("set")))),
+                ws(Target::parse),
+                ws(char('=')),
+            )),
+            ws(Expr::parse),
+        ))),
+    );
+    let (i, (target, expr)) = p(i)?;
+    Ok((i, CondTest { target, expr }))
+}
+
+fn cond_block<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Cond<'a>> {
+    let mut p = tuple((
+        |i| tag_block_start(i, s),
+        opt(expr_handle_ws),
+        ws(keyword("else")),
+        cut(tuple((
+            opt(cond_if),
+            opt(expr_handle_ws),
+            |i| tag_block_end(i, s),
+            cut(|i| parse_template(i, s)),
+        ))),
+    ));
+    let (i, (_, pws, _, (cond, nws, _, block))) = p(i)?;
+    Ok((i, (Ws(pws, nws), cond, block)))
+}
+
+fn block_if<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        opt(expr_handle_ws),
+        cond_if,
+        cut(tuple((
+            opt(expr_handle_ws),
+            |i| tag_block_end(i, s),
+            cut(tuple((
+                |i| parse_template(i, s),
+                many0(|i| cond_block(i, s)),
+                cut(tuple((
+                    |i| tag_block_start(i, s),
+                    opt(expr_handle_ws),
+                    ws(keyword("endif")),
+                    opt(expr_handle_ws),
+                ))),
+            ))),
+        ))),
+    ));
+    let (i, (pws1, cond, (nws1, _, (block, elifs, (_, pws2, _, nws2))))) = p(i)?;
+
+    let mut res = vec![(Ws(pws1, nws1), Some(cond), block)];
+    res.extend(elifs);
+    Ok((i, Node::Cond(res, Ws(pws2, nws2))))
+}
+
+fn match_else_block<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, When<'a>> {
+    let mut p = tuple((
+        |i| tag_block_start(i, s),
+        opt(expr_handle_ws),
+        ws(keyword("else")),
+        cut(tuple((
+            opt(expr_handle_ws),
+            |i| tag_block_end(i, s),
+            cut(|i| parse_template(i, s)),
+        ))),
+    ));
+    let (i, (_, pws, _, (nws, _, block))) = p(i)?;
+    Ok((i, (Ws(pws, nws), Target::Name("_"), block)))
+}
+
+fn when_block<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, When<'a>> {
+    let mut p = tuple((
+        |i| tag_block_start(i, s),
+        opt(expr_handle_ws),
+        ws(keyword("when")),
+        cut(tuple((
+            ws(Target::parse),
+            opt(expr_handle_ws),
+            |i| tag_block_end(i, s),
+            cut(|i| parse_template(i, s)),
+        ))),
+    ));
+    let (i, (_, pws, _, (target, nws, _, block))) = p(i)?;
+    Ok((i, (Ws(pws, nws), target, block)))
+}
+
+fn block_match<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        opt(expr_handle_ws),
+        ws(keyword("match")),
+        cut(tuple((
+            ws(Expr::parse),
+            opt(expr_handle_ws),
+            |i| tag_block_end(i, s),
+            cut(tuple((
+                ws(many0(ws(value((), |i| block_comment(i, s))))),
+                many1(|i| when_block(i, s)),
+                cut(tuple((
+                    opt(|i| match_else_block(i, s)),
+                    cut(tuple((
+                        ws(|i| tag_block_start(i, s)),
+                        opt(expr_handle_ws),
+                        ws(keyword("endmatch")),
+                        opt(expr_handle_ws),
+                    ))),
+                ))),
+            ))),
+        ))),
+    ));
+    let (i, (pws1, _, (expr, nws1, _, (_, arms, (else_arm, (_, pws2, _, nws2)))))) = p(i)?;
+
+    let mut arms = arms;
+    if let Some(arm) = else_arm {
+        arms.push(arm);
+    }
+
+    Ok((i, Node::Match(Ws(pws1, nws1), expr, arms, Ws(pws2, nws2))))
+}
+
+fn block_let(i: &str) -> IResult<&str, Node<'_>> {
+    let mut p = tuple((
+        opt(expr_handle_ws),
+        ws(alt((keyword("let"), keyword("set")))),
+        cut(tuple((
+            ws(Target::parse),
+            opt(tuple((ws(char('=')), ws(Expr::parse)))),
+            opt(expr_handle_ws),
+        ))),
+    ));
+    let (i, (pws, _, (var, val, nws))) = p(i)?;
+
+    Ok((
+        i,
+        if let Some((_, val)) = val {
+            Node::Let(Ws(pws, nws), var, val)
+        } else {
+            Node::LetDecl(Ws(pws, nws), var)
+        },
+    ))
+}
+
+fn parse_loop_content<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Vec<Node<'a>>> {
+    s.enter_loop();
+    let result = parse_template(i, s);
+    s.leave_loop();
+    result
+}
+
+fn block_for<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let if_cond = preceded(ws(keyword("if")), cut(ws(Expr::parse)));
+    let else_block = |i| {
+        let mut p = preceded(
+            ws(keyword("else")),
+            cut(tuple((
+                opt(expr_handle_ws),
+                delimited(
+                    |i| tag_block_end(i, s),
+                    |i| parse_template(i, s),
+                    |i| tag_block_start(i, s),
+                ),
+                opt(expr_handle_ws),
+            ))),
+        );
+        let (i, (pws, nodes, nws)) = p(i)?;
+        Ok((i, (pws, nodes, nws)))
+    };
+    let mut p = tuple((
+        opt(expr_handle_ws),
+        ws(keyword("for")),
+        cut(tuple((
+            ws(Target::parse),
+            ws(keyword("in")),
+            cut(tuple((
+                ws(Expr::parse),
+                opt(if_cond),
+                opt(expr_handle_ws),
+                |i| tag_block_end(i, s),
+                cut(tuple((
+                    |i| parse_loop_content(i, s),
+                    cut(tuple((
+                        |i| tag_block_start(i, s),
+                        opt(expr_handle_ws),
+                        opt(else_block),
+                        ws(keyword("endfor")),
+                        opt(expr_handle_ws),
+                    ))),
+                ))),
+            ))),
+        ))),
+    ));
+    let (i, (pws1, _, (var, _, (iter, cond, nws1, _, (body, (_, pws2, else_block, _, nws2)))))) =
+        p(i)?;
+    let (nws3, else_block, pws3) = else_block.unwrap_or_default();
+    Ok((
+        i,
+        Node::Loop(Loop {
+            ws1: Ws(pws1, nws1),
+            var,
+            iter,
+            cond,
+            body,
+            ws2: Ws(pws2, nws3),
+            else_block,
+            ws3: Ws(pws3, nws2),
+        }),
+    ))
+}
+
+fn block_extends(i: &str) -> IResult<&str, Node<'_>> {
+    let (i, (_, name)) = tuple((ws(keyword("extends")), ws(str_lit)))(i)?;
+    Ok((i, Node::Extends(name)))
+}
+
+fn block_block<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut start = tuple((
+        opt(expr_handle_ws),
+        ws(keyword("block")),
+        cut(tuple((ws(identifier), opt(expr_handle_ws), |i| {
+            tag_block_end(i, s)
+        }))),
+    ));
+    let (i, (pws1, _, (name, nws1, _))) = start(i)?;
+
+    let mut end = cut(tuple((
+        |i| parse_template(i, s),
+        cut(tuple((
+            |i| tag_block_start(i, s),
+            opt(expr_handle_ws),
+            ws(keyword("endblock")),
+            cut(tuple((opt(ws(keyword(name))), opt(expr_handle_ws)))),
+        ))),
+    )));
+    let (i, (contents, (_, pws2, _, (_, nws2)))) = end(i)?;
+
+    Ok((
+        i,
+        Node::BlockDef(Ws(pws1, nws1), name, contents, Ws(pws2, nws2)),
+    ))
+}
+
+fn block_include(i: &str) -> IResult<&str, Node<'_>> {
+    let mut p = tuple((
+        opt(expr_handle_ws),
+        ws(keyword("include")),
+        cut(pair(ws(str_lit), opt(expr_handle_ws))),
+    ));
+    let (i, (pws, _, (name, nws))) = p(i)?;
+    Ok((i, Node::Include(Ws(pws, nws), name)))
+}
+
+fn block_import(i: &str) -> IResult<&str, Node<'_>> {
+    let mut p = tuple((
+        opt(expr_handle_ws),
+        ws(keyword("import")),
+        cut(tuple((
+            ws(str_lit),
+            ws(keyword("as")),
+            cut(pair(ws(identifier), opt(expr_handle_ws))),
+        ))),
+    ));
+    let (i, (pws, _, (name, _, (scope, nws)))) = p(i)?;
+    Ok((i, Node::Import(Ws(pws, nws), name, scope)))
+}
+
+fn block_macro<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut start = tuple((
+        opt(expr_handle_ws),
+        ws(keyword("macro")),
+        cut(tuple((
+            ws(identifier),
+            ws(parameters),
+            opt(expr_handle_ws),
+            |i| tag_block_end(i, s),
+        ))),
+    ));
+    let (i, (pws1, _, (name, params, nws1, _))) = start(i)?;
+
+    let mut end = cut(tuple((
+        |i| parse_template(i, s),
+        cut(tuple((
+            |i| tag_block_start(i, s),
+            opt(expr_handle_ws),
+            ws(keyword("endmacro")),
+            cut(tuple((opt(ws(keyword(name))), opt(expr_handle_ws)))),
+        ))),
+    )));
+    let (i, (contents, (_, pws2, _, (_, nws2)))) = end(i)?;
+
+    assert_ne!(name, "super", "invalid macro name 'super'");
+
+    Ok((
+        i,
+        Node::Macro(
+            name,
+            Macro {
+                ws1: Ws(pws1, nws1),
+                args: params,
+                nodes: contents,
+                ws2: Ws(pws2, nws2),
+            },
+        ),
+    ))
+}
+
+fn block_raw<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let endraw = tuple((
+        |i| tag_block_start(i, s),
+        opt(expr_handle_ws),
+        ws(keyword("endraw")),
+        opt(expr_handle_ws),
+        peek(|i| tag_block_end(i, s)),
+    ));
+
+    let mut p = tuple((
+        opt(expr_handle_ws),
+        ws(keyword("raw")),
+        cut(tuple((
+            opt(expr_handle_ws),
+            |i| tag_block_end(i, s),
+            consumed(skip_till(endraw)),
+        ))),
+    ));
+
+    let (_, (pws1, _, (nws1, _, (contents, (i, (_, pws2, _, nws2, _)))))) = p(i)?;
+    let (lws, val, rws) = match split_ws_parts(contents) {
+        Node::Lit(lws, val, rws) => (lws, val, rws),
+        _ => unreachable!(),
+    };
+    let ws1 = Ws(pws1, nws1);
+    let ws2 = Ws(pws2, nws2);
+    Ok((i, Node::Raw(ws1, lws, val, rws, ws2)))
+}
+
+fn break_statement<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        opt(expr_handle_ws),
+        ws(keyword("break")),
+        opt(expr_handle_ws),
+    ));
+    let (j, (pws, _, nws)) = p(i)?;
+    if !s.is_in_loop() {
+        return Err(nom::Err::Failure(error_position!(i, ErrorKind::Tag)));
+    }
+    Ok((j, Node::Break(Ws(pws, nws))))
+}
+
+fn continue_statement<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        opt(expr_handle_ws),
+        ws(keyword("continue")),
+        opt(expr_handle_ws),
+    ));
+    let (j, (pws, _, nws)) = p(i)?;
+    if !s.is_in_loop() {
+        return Err(nom::Err::Failure(error_position!(i, ErrorKind::Tag)));
+    }
+    Ok((j, Node::Continue(Ws(pws, nws))))
+}
+
+fn block_node<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        |i| tag_block_start(i, s),
+        alt((
+            block_call,
+            block_let,
+            |i| block_if(i, s),
+            |i| block_for(i, s),
+            |i| block_match(i, s),
+            block_extends,
+            block_include,
+            block_import,
+            |i| block_block(i, s),
+            |i| block_macro(i, s),
+            |i| block_raw(i, s),
+            |i| break_statement(i, s),
+            |i| continue_statement(i, s),
+        )),
+        cut(|i| tag_block_end(i, s)),
+    ));
+    let (i, (_, contents, _)) = p(i)?;
+    Ok((i, contents))
+}
+
+fn block_comment_body<'a>(mut i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
+    let mut level = 0;
+    loop {
+        let (end, tail) = take_until(s.syntax.comment_end)(i)?;
+        match take_until::<_, _, Error<_>>(s.syntax.comment_start)(i) {
+            Ok((start, _)) if start.as_ptr() < end.as_ptr() => {
+                level += 1;
+                i = &start[2..];
+            }
+            _ if level > 0 => {
+                level -= 1;
+                i = &end[2..];
+            }
+            _ => return Ok((end, tail)),
+        }
+    }
+}
+
+fn block_comment<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        |i| tag_comment_start(i, s),
+        cut(tuple((
+            opt(expr_handle_ws),
+            |i| block_comment_body(i, s),
+            |i| tag_comment_end(i, s),
+        ))),
+    ));
+    let (i, (_, (pws, tail, _))) = p(i)?;
+    let nws = if tail.ends_with('-') {
+        Some(Whitespace::Suppress)
+    } else if tail.ends_with('+') {
+        Some(Whitespace::Preserve)
+    } else if tail.ends_with('~') {
+        Some(Whitespace::Minimize)
+    } else {
+        None
+    };
+    Ok((i, Node::Comment(Ws(pws, nws))))
+}
+
+fn expr_node<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
+    let mut p = tuple((
+        |i| tag_expr_start(i, s),
+        cut(tuple((
+            opt(expr_handle_ws),
+            ws(Expr::parse),
+            opt(expr_handle_ws),
+            |i| tag_expr_end(i, s),
+        ))),
+    ));
+    let (i, (_, (pws, expr, nws, _))) = p(i)?;
+    Ok((i, Node::Expr(Ws(pws, nws), expr)))
+}
+
+fn parse_template<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Vec<Node<'a>>> {
+    many0(alt((
+        complete(|i| take_content(i, s)),
+        complete(|i| block_comment(i, s)),
+        complete(|i| expr_node(i, s)),
+        complete(|i| block_node(i, s)),
+    )))(i)
+}
+
+fn variant_lit(i: &str) -> IResult<&str, Target<'_>> {
+    alt((
+        map(str_lit, Target::StrLit),
+        map(char_lit, Target::CharLit),
+        map(num_lit, Target::NumLit),
+        map(bool_lit, Target::BoolLit),
+    ))(i)
+}
+
+fn target(i: &str) -> IResult<&str, Target<'_>> {
+    let mut opt_opening_paren = map(opt(ws(char('('))), |o| o.is_some());
+    let mut opt_closing_paren = map(opt(ws(char(')'))), |o| o.is_some());
+    let mut opt_opening_brace = map(opt(ws(char('{'))), |o| o.is_some());
+
+    let (i, lit) = opt(variant_lit)(i)?;
+    if let Some(lit) = lit {
+        return Ok((i, lit));
+    }
+
+    // match tuples and unused parentheses
+    let (i, target_is_tuple) = opt_opening_paren(i)?;
+    if target_is_tuple {
+        let (i, is_empty_tuple) = opt_closing_paren(i)?;
+        if is_empty_tuple {
+            return Ok((i, Target::Tuple(Vec::new(), Vec::new())));
+        }
+
+        let (i, first_target) = target(i)?;
+        let (i, is_unused_paren) = opt_closing_paren(i)?;
+        if is_unused_paren {
+            return Ok((i, first_target));
+        }
+
+        let mut targets = vec![first_target];
+        let (i, _) = cut(tuple((
+            fold_many0(
+                preceded(ws(char(',')), target),
+                || (),
+                |_, target| {
+                    targets.push(target);
+                },
+            ),
+            opt(ws(char(','))),
+            ws(cut(char(')'))),
+        )))(i)?;
+        return Ok((i, Target::Tuple(Vec::new(), targets)));
+    }
+
+    // match structs
+    let (i, path) = opt(path)(i)?;
+    if let Some(path) = path {
+        let i_before_matching_with = i;
+        let (i, _) = opt(ws(keyword("with")))(i)?;
+
+        let (i, is_unnamed_struct) = opt_opening_paren(i)?;
+        if is_unnamed_struct {
+            let (i, targets) = alt((
+                map(char(')'), |_| Vec::new()),
+                terminated(
+                    cut(separated_list1(ws(char(',')), target)),
+                    pair(opt(ws(char(','))), ws(cut(char(')')))),
+                ),
+            ))(i)?;
+            return Ok((i, Target::Tuple(path, targets)));
+        }
+
+        let (i, is_named_struct) = opt_opening_brace(i)?;
+        if is_named_struct {
+            let (i, targets) = alt((
+                map(char('}'), |_| Vec::new()),
+                terminated(
+                    cut(separated_list1(ws(char(',')), named_target)),
+                    pair(opt(ws(char(','))), ws(cut(char('}')))),
+                ),
+            ))(i)?;
+            return Ok((i, Target::Struct(path, targets)));
+        }
+
+        return Ok((i_before_matching_with, Target::Path(path)));
+    }
+
+    // neither literal nor struct nor path
+    map(identifier, Target::Name)(i)
+}
+
+fn named_target(i: &str) -> IResult<&str, (&str, Target<'_>)> {
+    let (i, (src, target)) = pair(identifier, opt(preceded(ws(char(':')), target)))(i)?;
+    Ok((i, (src, target.unwrap_or(Target::Name(src)))))
+}
diff --git a/third_party/rust/askama_derive/src/parser/tests.rs b/third_party/rust/askama_derive/src/parser/tests.rs
new file mode 100644
index 0000000000..91bb09ba8d
--- /dev/null
+++ b/third_party/rust/askama_derive/src/parser/tests.rs
@@ -0,0 +1,668 @@
+use crate::config::Syntax;
+use crate::parser::{Expr, Node, Whitespace, Ws};
+
+fn check_ws_split(s: &str, res: &(&str, &str, &str)) {
+    match super::split_ws_parts(s) {
+        Node::Lit(lws, s, rws) => {
+            assert_eq!(lws, res.0);
+            assert_eq!(s, res.1);
+            assert_eq!(rws, res.2);
+        }
+        _ => {
+            panic!("fail");
+        }
+    }
+}
+
+#[test]
+fn test_ws_splitter() {
+    check_ws_split("", &("", "", ""));
+    check_ws_split("a", &("", "a", ""));
+    check_ws_split("\ta", &("\t", "a", ""));
+    check_ws_split("b\n", &("", "b", "\n"));
+    check_ws_split(" \t\r\n", &(" \t\r\n", "", ""));
+}
+
+#[test]
+#[should_panic]
+fn test_invalid_block() {
+    super::parse("{% extend \"blah\" %}", &Syntax::default()).unwrap();
+}
+
+#[test]
+fn test_parse_filter() {
+    use Expr::*;
+    let syntax = Syntax::default();
+    assert_eq!(
+        super::parse("{{ strvar|e }}", &syntax).unwrap(),
+        vec![Node::Expr(Ws(None, None), Filter("e", vec![Var("strvar")]),)],
+    );
+    assert_eq!(
+        super::parse("{{ 2|abs }}", &syntax).unwrap(),
+        vec![Node::Expr(Ws(None, None), Filter("abs", vec![NumLit("2")]),)],
+    );
+    assert_eq!(
+        super::parse("{{ -2|abs }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Filter("abs", vec![Unary("-", NumLit("2").into())]),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ (1 - 2)|abs }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Filter(
+                "abs",
+                vec![Group(
+                    BinOp("-", NumLit("1").into(), NumLit("2").into()).into()
+                )]
+            ),
+        )],
+    );
+}
+
+#[test]
+fn test_parse_numbers() {
+    let syntax = Syntax::default();
+    assert_eq!(
+        super::parse("{{ 2 }}", &syntax).unwrap(),
+        vec![Node::Expr(Ws(None, None), Expr::NumLit("2"),)],
+    );
+    assert_eq!(
+        super::parse("{{ 2.5 }}", &syntax).unwrap(),
+        vec![Node::Expr(Ws(None, None), Expr::NumLit("2.5"),)],
+    );
+}
+
+#[test]
+fn test_parse_var() {
+    let s = Syntax::default();
+
+    assert_eq!(
+        super::parse("{{ foo }}", &s).unwrap(),
+        vec![Node::Expr(Ws(None, None), Expr::Var("foo"))],
+    );
+    assert_eq!(
+        super::parse("{{ foo_bar }}", &s).unwrap(),
+        vec![Node::Expr(Ws(None, None), Expr::Var("foo_bar"))],
+    );
+
+    assert_eq!(
+        super::parse("{{ none }}", &s).unwrap(),
+        vec![Node::Expr(Ws(None, None), Expr::Var("none"))],
+    );
+}
+
+#[test]
+fn test_parse_const() {
+    let s = Syntax::default();
+
+    assert_eq!(
+        super::parse("{{ FOO }}", &s).unwrap(),
+        vec![Node::Expr(Ws(None, None), Expr::Path(vec!["FOO"]))],
+    );
+    assert_eq!(
+        super::parse("{{ FOO_BAR }}", &s).unwrap(),
+        vec![Node::Expr(Ws(None, None), Expr::Path(vec!["FOO_BAR"]))],
+    );
+
+    assert_eq!(
+        super::parse("{{ NONE }}", &s).unwrap(),
+        vec![Node::Expr(Ws(None, None), Expr::Path(vec!["NONE"]))],
+    );
+}
+
+#[test]
+fn test_parse_path() {
+    let s = Syntax::default();
+
+    assert_eq!(
+        super::parse("{{ None }}", &s).unwrap(),
+        vec![Node::Expr(Ws(None, None), Expr::Path(vec!["None"]))],
+    );
+    assert_eq!(
+        super::parse("{{ Some(123) }}", &s).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Expr::Call(
+                Box::new(Expr::Path(vec!["Some"])),
+                vec![Expr::NumLit("123")]
+            ),
+        )],
+    );
+
+    assert_eq!(
+        super::parse("{{ Ok(123) }}", &s).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Expr::Call(Box::new(Expr::Path(vec!["Ok"])), vec![Expr::NumLit("123")]),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ Err(123) }}", &s).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Expr::Call(Box::new(Expr::Path(vec!["Err"])), vec![Expr::NumLit("123")]),
+        )],
+    );
+}
+
+#[test]
+fn test_parse_var_call() {
+    assert_eq!(
+        super::parse("{{ function(\"123\", 3) }}", &Syntax::default()).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Expr::Call(
+                Box::new(Expr::Var("function")),
+                vec![Expr::StrLit("123"), Expr::NumLit("3")]
+            ),
+        )],
+    );
+}
+
+#[test]
+fn test_parse_path_call() {
+    let s = Syntax::default();
+
+    assert_eq!(
+        super::parse("{{ Option::None }}", &s).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Expr::Path(vec!["Option", "None"])
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ Option::Some(123) }}", &s).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Expr::Call(
+                Box::new(Expr::Path(vec!["Option", "Some"])),
+                vec![Expr::NumLit("123")],
+            ),
+        )],
+    );
+
+    assert_eq!(
+        super::parse("{{ self::function(\"123\", 3) }}", &s).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Expr::Call(
+                Box::new(Expr::Path(vec!["self", "function"])),
+                vec![Expr::StrLit("123"), Expr::NumLit("3")],
+            ),
+        )],
+    );
+}
+
+#[test]
+fn test_parse_root_path() {
+    let syntax = Syntax::default();
+    assert_eq!(
+        super::parse("{{ std::string::String::new() }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Expr::Call(
+                Box::new(Expr::Path(vec!["std", "string", "String", "new"])),
+                vec![]
+            ),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ ::std::string::String::new() }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Expr::Call(
+                Box::new(Expr::Path(vec!["", "std", "string", "String", "new"])),
+                vec![]
+            ),
+        )],
+    );
+}
+
+#[test]
+fn change_delimiters_parse_filter() {
+    let syntax = Syntax {
+        expr_start: "{=",
+        expr_end: "=}",
+        ..Syntax::default()
+    };
+
+    super::parse("{= strvar|e =}", &syntax).unwrap();
+}
+
+#[test]
+fn test_precedence() {
+    use Expr::*;
+    let syntax = Syntax::default();
+    assert_eq!(
+        super::parse("{{ a + b == c }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "==",
+                BinOp("+", Var("a").into(), Var("b").into()).into(),
+                Var("c").into(),
+            )
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ a + b * c - d / e }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "-",
+                BinOp(
+                    "+",
+                    Var("a").into(),
+                    BinOp("*", Var("b").into(), Var("c").into()).into(),
+                )
+                .into(),
+                BinOp("/", Var("d").into(), Var("e").into()).into(),
+            )
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ a * (b + c) / -d }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "/",
+                BinOp(
+                    "*",
+                    Var("a").into(),
+                    Group(BinOp("+", Var("b").into(), Var("c").into()).into()).into()
+                )
+                .into(),
+                Unary("-", Var("d").into()).into()
+            )
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ a || b && c || d && e }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "||",
+                BinOp(
+                    "||",
+                    Var("a").into(),
+                    BinOp("&&", Var("b").into(), Var("c").into()).into(),
+                )
+                .into(),
+                BinOp("&&", Var("d").into(), Var("e").into()).into(),
+            )
+        )],
+    );
+}
+
+#[test]
+fn test_associativity() {
+    use Expr::*;
+    let syntax = Syntax::default();
+    assert_eq!(
+        super::parse("{{ a + b + c }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "+",
+                BinOp("+", Var("a").into(), Var("b").into()).into(),
+                Var("c").into()
+            )
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ a * b * c }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "*",
+                BinOp("*", Var("a").into(), Var("b").into()).into(),
+                Var("c").into()
+            )
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ a && b && c }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "&&",
+                BinOp("&&", Var("a").into(), Var("b").into()).into(),
+                Var("c").into()
+            )
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ a + b - c + d }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "+",
+                BinOp(
+                    "-",
+                    BinOp("+", Var("a").into(), Var("b").into()).into(),
+                    Var("c").into()
+                )
+                .into(),
+                Var("d").into()
+            )
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ a == b != c > d > e == f }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "==",
+                BinOp(
+                    ">",
+                    BinOp(
+                        ">",
+                        BinOp(
+                            "!=",
+                            BinOp("==", Var("a").into(), Var("b").into()).into(),
+                            Var("c").into()
+                        )
+                        .into(),
+                        Var("d").into()
+                    )
+                    .into(),
+                    Var("e").into()
+                )
+                .into(),
+                Var("f").into()
+            )
+        )],
+    );
+}
+
+#[test]
+fn test_odd_calls() {
+    use Expr::*;
+    let syntax = Syntax::default();
+    assert_eq!(
+        super::parse("{{ a[b](c) }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Call(
+                Box::new(Index(Box::new(Var("a")), Box::new(Var("b")))),
+                vec![Var("c")],
+            ),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ (a + b)(c) }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Call(
+                Box::new(Group(Box::new(BinOp(
+                    "+",
+                    Box::new(Var("a")),
+                    Box::new(Var("b"))
+                )))),
+                vec![Var("c")],
+            ),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ a + b(c) }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "+",
+                Box::new(Var("a")),
+                Box::new(Call(Box::new(Var("b")), vec![Var("c")])),
+            ),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ (-a)(b) }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Call(
+                Box::new(Group(Box::new(Unary("-", Box::new(Var("a")))))),
+                vec![Var("b")],
+            ),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ -a(b) }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Unary("-", Box::new(Call(Box::new(Var("a")), vec![Var("b")])),),
+        )],
+    );
+}
+
+#[test]
+fn test_parse_comments() {
+    let s = &Syntax::default();
+
+    assert_eq!(
+        super::parse("{##}", s).unwrap(),
+        vec![Node::Comment(Ws(None, None))],
+    );
+    assert_eq!(
+        super::parse("{#- #}", s).unwrap(),
+        vec![Node::Comment(Ws(Some(Whitespace::Suppress), None))],
+    );
+    assert_eq!(
+        super::parse("{# -#}", s).unwrap(),
+        vec![Node::Comment(Ws(None, Some(Whitespace::Suppress)))],
+    );
+    assert_eq!(
+        super::parse("{#--#}", s).unwrap(),
+        vec![Node::Comment(Ws(
+            Some(Whitespace::Suppress),
+            Some(Whitespace::Suppress)
+        ))],
+    );
+    assert_eq!(
+        super::parse("{#- foo\n bar -#}", s).unwrap(),
+        vec![Node::Comment(Ws(
+            Some(Whitespace::Suppress),
+            Some(Whitespace::Suppress)
+        ))],
+    );
+    assert_eq!(
+        super::parse("{#- foo\n {#- bar\n -#} baz -#}", s).unwrap(),
+        vec![Node::Comment(Ws(
+            Some(Whitespace::Suppress),
+            Some(Whitespace::Suppress)
+        ))],
+    );
+    assert_eq!(
+        super::parse("{#+ #}", s).unwrap(),
+        vec![Node::Comment(Ws(Some(Whitespace::Preserve), None))],
+    );
+    assert_eq!(
+        super::parse("{# +#}", s).unwrap(),
+        vec![Node::Comment(Ws(None, Some(Whitespace::Preserve)))],
+    );
+    assert_eq!(
+        super::parse("{#++#}", s).unwrap(),
+        vec![Node::Comment(Ws(
+            Some(Whitespace::Preserve),
+            Some(Whitespace::Preserve)
+        ))],
+    );
+    assert_eq!(
+        super::parse("{#+ foo\n bar +#}", s).unwrap(),
+        vec![Node::Comment(Ws(
+            Some(Whitespace::Preserve),
+            Some(Whitespace::Preserve)
+        ))],
+    );
+    assert_eq!(
+        super::parse("{#+ foo\n {#+ bar\n +#} baz -+#}", s).unwrap(),
+        vec![Node::Comment(Ws(
+            Some(Whitespace::Preserve),
+            Some(Whitespace::Preserve)
+        ))],
+    );
+    assert_eq!(
+        super::parse("{#~ #}", s).unwrap(),
+        vec![Node::Comment(Ws(Some(Whitespace::Minimize), None))],
+    );
+    assert_eq!(
+        super::parse("{# ~#}", s).unwrap(),
+        vec![Node::Comment(Ws(None, Some(Whitespace::Minimize)))],
+    );
+    assert_eq!(
+        super::parse("{#~~#}", s).unwrap(),
+        vec![Node::Comment(Ws(
+            Some(Whitespace::Minimize),
+            Some(Whitespace::Minimize)
+        ))],
+    );
+    assert_eq!(
+        super::parse("{#~ foo\n bar ~#}", s).unwrap(),
+        vec![Node::Comment(Ws(
+            Some(Whitespace::Minimize),
+            Some(Whitespace::Minimize)
+        ))],
+    );
+    assert_eq!(
+        super::parse("{#~ foo\n {#~ bar\n ~#} baz -~#}", s).unwrap(),
+        vec![Node::Comment(Ws(
+            Some(Whitespace::Minimize),
+            Some(Whitespace::Minimize)
+        ))],
+    );
+
+    assert_eq!(
+        super::parse("{# foo {# bar #} {# {# baz #} qux #} #}", s).unwrap(),
+        vec![Node::Comment(Ws(None, None))],
+    );
+}
+
+#[test]
+fn test_parse_tuple() {
+    use super::Expr::*;
+    let syntax = Syntax::default();
+    assert_eq!(
+        super::parse("{{ () }}", &syntax).unwrap(),
+        vec![Node::Expr(Ws(None, None), Tuple(vec![]),)],
+    );
+    assert_eq!(
+        super::parse("{{ (1) }}", &syntax).unwrap(),
+        vec![Node::Expr(Ws(None, None), Group(Box::new(NumLit("1"))),)],
+    );
+    assert_eq!(
+        super::parse("{{ (1,) }}", &syntax).unwrap(),
+        vec![Node::Expr(Ws(None, None), Tuple(vec![NumLit("1")]),)],
+    );
+    assert_eq!(
+        super::parse("{{ (1, ) }}", &syntax).unwrap(),
+        vec![Node::Expr(Ws(None, None), Tuple(vec![NumLit("1")]),)],
+    );
+    assert_eq!(
+        super::parse("{{ (1 ,) }}", &syntax).unwrap(),
+        vec![Node::Expr(Ws(None, None), Tuple(vec![NumLit("1")]),)],
+    );
+    assert_eq!(
+        super::parse("{{ (1 , ) }}", &syntax).unwrap(),
+        vec![Node::Expr(Ws(None, None), Tuple(vec![NumLit("1")]),)],
+    );
+    assert_eq!(
+        super::parse("{{ (1, 2) }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Tuple(vec![NumLit("1"), NumLit("2")]),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ (1, 2,) }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Tuple(vec![NumLit("1"), NumLit("2")]),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ (1, 2, 3) }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Tuple(vec![NumLit("1"), NumLit("2"), NumLit("3")]),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ ()|abs }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Filter("abs", vec![Tuple(vec![])]),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ () | abs }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp("|", Box::new(Tuple(vec![])), Box::new(Var("abs"))),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ (1)|abs }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Filter("abs", vec![Group(Box::new(NumLit("1")))]),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ (1) | abs }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "|",
+                Box::new(Group(Box::new(NumLit("1")))),
+                Box::new(Var("abs"))
+            ),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ (1,)|abs }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Filter("abs", vec![Tuple(vec![NumLit("1")])]),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ (1,) | abs }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "|",
+                Box::new(Tuple(vec![NumLit("1")])),
+                Box::new(Var("abs"))
+            ),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ (1, 2)|abs }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            Filter("abs", vec![Tuple(vec![NumLit("1"), NumLit("2")])]),
+        )],
+    );
+    assert_eq!(
+        super::parse("{{ (1, 2) | abs }}", &syntax).unwrap(),
+        vec![Node::Expr(
+            Ws(None, None),
+            BinOp(
+                "|",
+                Box::new(Tuple(vec![NumLit("1"), NumLit("2")])),
+                Box::new(Var("abs"))
+            ),
+        )],
+    );
+}
+
+#[test]
+fn test_missing_space_after_kw() {
+    let syntax = Syntax::default();
+    let err = super::parse("{%leta=b%}", &syntax).unwrap_err();
+    assert!(matches!(
+        &*err.msg,
+        "unable to parse template:\n\n\"{%leta=b%}\""
+    ));
+}