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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
| commit | 26a029d407be480d791972afb5975cf62c9360a6 (patch) | |
| tree | f435a8308119effd964b339f76abb83a57c29483 /third_party/rust/displaydoc/src | |
| parent | Initial commit. (diff) | |
| download | firefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz firefox-26a029d407be480d791972afb5975cf62c9360a6.zip | |
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/rust/displaydoc/src')
| -rw-r--r-- | third_party/rust/displaydoc/src/attr.rs | 137 | ||||
| -rw-r--r-- | third_party/rust/displaydoc/src/expand.rs | 410 | ||||
| -rw-r--r-- | third_party/rust/displaydoc/src/fmt.rs | 159 | ||||
| -rw-r--r-- | third_party/rust/displaydoc/src/lib.rs | 187 |
4 files changed, 893 insertions, 0 deletions
diff --git a/third_party/rust/displaydoc/src/attr.rs b/third_party/rust/displaydoc/src/attr.rs new file mode 100644 index 0000000000..a965d04deb --- /dev/null +++ b/third_party/rust/displaydoc/src/attr.rs @@ -0,0 +1,137 @@ +use proc_macro2::TokenStream;
+use quote::{quote, ToTokens};
+use syn::{Attribute, LitStr, Meta, Result};
+
+#[derive(Clone)]
+pub(crate) struct Display {
+ pub(crate) fmt: LitStr,
+ pub(crate) args: TokenStream,
+}
+
+pub(crate) struct VariantDisplay {
+ pub(crate) r#enum: Option<Display>,
+ pub(crate) variant: Display,
+}
+
+impl ToTokens for Display {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ let fmt = &self.fmt;
+ let args = &self.args;
+ tokens.extend(quote! {
+ write!(formatter, #fmt #args)
+ });
+ }
+}
+
+impl ToTokens for VariantDisplay {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ if let Some(ref r#enum) = self.r#enum {
+ r#enum.to_tokens(tokens);
+ tokens.extend(quote! { ?; write!(formatter, ": ")?; });
+ }
+ self.variant.to_tokens(tokens);
+ }
+}
+
+pub(crate) struct AttrsHelper {
+ ignore_extra_doc_attributes: bool,
+ prefix_enum_doc_attributes: bool,
+}
+
+impl AttrsHelper {
+ pub(crate) fn new(attrs: &[Attribute]) -> Self {
+ let ignore_extra_doc_attributes = attrs
+ .iter()
+ .any(|attr| attr.path().is_ident("ignore_extra_doc_attributes"));
+ let prefix_enum_doc_attributes = attrs
+ .iter()
+ .any(|attr| attr.path().is_ident("prefix_enum_doc_attributes"));
+
+ Self {
+ ignore_extra_doc_attributes,
+ prefix_enum_doc_attributes,
+ }
+ }
+
+ pub(crate) fn display(&self, attrs: &[Attribute]) -> Result<Option<Display>> {
+ let displaydoc_attr = attrs.iter().find(|attr| attr.path().is_ident("displaydoc"));
+
+ if let Some(displaydoc_attr) = displaydoc_attr {
+ let lit = displaydoc_attr
+ .parse_args()
+ .expect("#[displaydoc(\"foo\")] must contain string arguments");
+ let mut display = Display {
+ fmt: lit,
+ args: TokenStream::new(),
+ };
+
+ display.expand_shorthand();
+ return Ok(Some(display));
+ }
+
+ let num_doc_attrs = attrs
+ .iter()
+ .filter(|attr| attr.path().is_ident("doc"))
+ .count();
+
+ if !self.ignore_extra_doc_attributes && num_doc_attrs > 1 {
+ panic!("Multi-line comments are disabled by default by displaydoc. Please consider using block doc comments (/** */) or adding the #[ignore_extra_doc_attributes] attribute to your type next to the derive.");
+ }
+
+ for attr in attrs {
+ if attr.path().is_ident("doc") {
+ let lit = match &attr.meta {
+ Meta::NameValue(syn::MetaNameValue {
+ value:
+ syn::Expr::Lit(syn::ExprLit {
+ lit: syn::Lit::Str(lit),
+ ..
+ }),
+ ..
+ }) => lit,
+ _ => unimplemented!(),
+ };
+
+ // Make an attempt at cleaning up multiline doc comments.
+ let doc_str = lit
+ .value()
+ .lines()
+ .map(|line| line.trim().trim_start_matches('*').trim())
+ .collect::<Vec<&str>>()
+ .join("\n");
+
+ let lit = LitStr::new(doc_str.trim(), lit.span());
+
+ let mut display = Display {
+ fmt: lit,
+ args: TokenStream::new(),
+ };
+
+ display.expand_shorthand();
+ return Ok(Some(display));
+ }
+ }
+
+ Ok(None)
+ }
+
+ pub(crate) fn display_with_input(
+ &self,
+ r#enum: &[Attribute],
+ variant: &[Attribute],
+ ) -> Result<Option<VariantDisplay>> {
+ let r#enum = if self.prefix_enum_doc_attributes {
+ let result = self
+ .display(r#enum)?
+ .expect("Missing doc comment on enum with #[prefix_enum_doc_attributes]. Please remove the attribute or add a doc comment to the enum itself.");
+
+ Some(result)
+ } else {
+ None
+ };
+
+ Ok(self
+ .display(variant)?
+ .map(|variant| VariantDisplay { r#enum, variant }))
+ }
+}
diff --git a/third_party/rust/displaydoc/src/expand.rs b/third_party/rust/displaydoc/src/expand.rs new file mode 100644 index 0000000000..8a84390be2 --- /dev/null +++ b/third_party/rust/displaydoc/src/expand.rs @@ -0,0 +1,410 @@ +use super::attr::AttrsHelper;
+use proc_macro2::{Span, TokenStream};
+use quote::{format_ident, quote};
+use syn::{
+ punctuated::Punctuated,
+ token::{Colon, Comma, PathSep, Plus, Where},
+ Data, DataEnum, DataStruct, DeriveInput, Error, Fields, Generics, Ident, Path, PathArguments,
+ PathSegment, PredicateType, Result, TraitBound, TraitBoundModifier, Type, TypeParam,
+ TypeParamBound, TypePath, WhereClause, WherePredicate,
+};
+
+use std::collections::HashMap;
+
+pub(crate) fn derive(input: &DeriveInput) -> Result<TokenStream> {
+ let impls = match &input.data {
+ Data::Struct(data) => impl_struct(input, data),
+ Data::Enum(data) => impl_enum(input, data),
+ Data::Union(_) => Err(Error::new_spanned(input, "Unions are not supported")),
+ }?;
+
+ let helpers = specialization();
+ let dummy_const = format_ident!("_DERIVE_Display_FOR_{}", input.ident);
+ Ok(quote! {
+ #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+ const #dummy_const: () = {
+ #helpers
+ #impls
+ };
+ })
+}
+
+#[cfg(feature = "std")]
+fn specialization() -> TokenStream {
+ quote! {
+ trait DisplayToDisplayDoc {
+ fn __displaydoc_display(&self) -> Self;
+ }
+
+ impl<T: core::fmt::Display> DisplayToDisplayDoc for &T {
+ fn __displaydoc_display(&self) -> Self {
+ self
+ }
+ }
+
+ // If the `std` feature gets enabled we want to ensure that any crate
+ // using displaydoc can still reference the std crate, which is already
+ // being compiled in by whoever enabled the `std` feature in
+ // `displaydoc`, even if the crates using displaydoc are no_std.
+ extern crate std;
+
+ trait PathToDisplayDoc {
+ fn __displaydoc_display(&self) -> std::path::Display<'_>;
+ }
+
+ impl PathToDisplayDoc for std::path::Path {
+ fn __displaydoc_display(&self) -> std::path::Display<'_> {
+ self.display()
+ }
+ }
+
+ impl PathToDisplayDoc for std::path::PathBuf {
+ fn __displaydoc_display(&self) -> std::path::Display<'_> {
+ self.display()
+ }
+ }
+ }
+}
+
+#[cfg(not(feature = "std"))]
+fn specialization() -> TokenStream {
+ quote! {}
+}
+
+fn impl_struct(input: &DeriveInput, data: &DataStruct) -> Result<TokenStream> {
+ let ty = &input.ident;
+ let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
+ let where_clause = generate_where_clause(&input.generics, where_clause);
+
+ let helper = AttrsHelper::new(&input.attrs);
+
+ let display = helper.display(&input.attrs)?.map(|display| {
+ let pat = match &data.fields {
+ Fields::Named(fields) => {
+ let var = fields.named.iter().map(|field| &field.ident);
+ quote!(Self { #(#var),* })
+ }
+ Fields::Unnamed(fields) => {
+ let var = (0..fields.unnamed.len()).map(|i| format_ident!("_{}", i));
+ quote!(Self(#(#var),*))
+ }
+ Fields::Unit => quote!(_),
+ };
+ quote! {
+ impl #impl_generics core::fmt::Display for #ty #ty_generics #where_clause {
+ fn fmt(&self, formatter: &mut core::fmt::Formatter) -> core::fmt::Result {
+ // NB: This destructures the fields of `self` into named variables (for unnamed
+ // fields, it uses _0, _1, etc as above). The `#[allow(unused_variables)]`
+ // section means it doesn't have to parse the individual field references out of
+ // the docstring.
+ #[allow(unused_variables)]
+ let #pat = self;
+ #display
+ }
+ }
+ }
+ });
+
+ Ok(quote! { #display })
+}
+
+/// Create a `where` predicate for `ident`, without any [bound][TypeParamBound]s yet.
+fn new_empty_where_type_predicate(ident: Ident) -> PredicateType {
+ let mut path_segments = Punctuated::<PathSegment, PathSep>::new();
+ path_segments.push_value(PathSegment {
+ ident,
+ arguments: PathArguments::None,
+ });
+ PredicateType {
+ lifetimes: None,
+ bounded_ty: Type::Path(TypePath {
+ qself: None,
+ path: Path {
+ leading_colon: None,
+ segments: path_segments,
+ },
+ }),
+ colon_token: Colon {
+ spans: [Span::call_site()],
+ },
+ bounds: Punctuated::<TypeParamBound, Plus>::new(),
+ }
+}
+
+/// Create a `where` clause that we can add [WherePredicate]s to.
+fn new_empty_where_clause() -> WhereClause {
+ WhereClause {
+ where_token: Where {
+ span: Span::call_site(),
+ },
+ predicates: Punctuated::<WherePredicate, Comma>::new(),
+ }
+}
+
+enum UseGlobalPrefix {
+ LeadingColon,
+ #[allow(dead_code)]
+ NoLeadingColon,
+}
+
+/// Create a path with segments composed of [Idents] *without* any [PathArguments].
+fn join_paths(name_segments: &[&str], use_global_prefix: UseGlobalPrefix) -> Path {
+ let mut segments = Punctuated::<PathSegment, PathSep>::new();
+ assert!(!name_segments.is_empty());
+ segments.push_value(PathSegment {
+ ident: Ident::new(name_segments[0], Span::call_site()),
+ arguments: PathArguments::None,
+ });
+ for name in name_segments[1..].iter() {
+ segments.push_punct(PathSep {
+ spans: [Span::call_site(), Span::mixed_site()],
+ });
+ segments.push_value(PathSegment {
+ ident: Ident::new(name, Span::call_site()),
+ arguments: PathArguments::None,
+ });
+ }
+ Path {
+ leading_colon: match use_global_prefix {
+ UseGlobalPrefix::LeadingColon => Some(PathSep {
+ spans: [Span::call_site(), Span::mixed_site()],
+ }),
+ UseGlobalPrefix::NoLeadingColon => None,
+ },
+ segments,
+ }
+}
+
+/// Push `new_type_predicate` onto the end of `where_clause`.
+fn append_where_clause_type_predicate(
+ where_clause: &mut WhereClause,
+ new_type_predicate: PredicateType,
+) {
+ // Push a comma at the end if there are already any `where` predicates.
+ if !where_clause.predicates.is_empty() {
+ where_clause.predicates.push_punct(Comma {
+ spans: [Span::call_site()],
+ });
+ }
+ where_clause
+ .predicates
+ .push_value(WherePredicate::Type(new_type_predicate));
+}
+
+/// Add a requirement for [core::fmt::Display] to a `where` predicate for some type.
+fn add_display_constraint_to_type_predicate(
+ predicate_that_needs_a_display_impl: &mut PredicateType,
+) {
+ // Create a `Path` of `::core::fmt::Display`.
+ let display_path = join_paths(&["core", "fmt", "Display"], UseGlobalPrefix::LeadingColon);
+
+ let display_bound = TypeParamBound::Trait(TraitBound {
+ paren_token: None,
+ modifier: TraitBoundModifier::None,
+ lifetimes: None,
+ path: display_path,
+ });
+ if !predicate_that_needs_a_display_impl.bounds.is_empty() {
+ predicate_that_needs_a_display_impl.bounds.push_punct(Plus {
+ spans: [Span::call_site()],
+ });
+ }
+
+ predicate_that_needs_a_display_impl
+ .bounds
+ .push_value(display_bound);
+}
+
+/// Map each declared generic type parameter to the set of all trait boundaries declared on it.
+///
+/// These boundaries may come from the declaration site:
+/// pub enum E<T: MyTrait> { ... }
+/// or a `where` clause after the parameter declarations:
+/// pub enum E<T> where T: MyTrait { ... }
+/// This method will return the boundaries from both of those cases.
+fn extract_trait_constraints_from_source(
+ where_clause: &WhereClause,
+ type_params: &[&TypeParam],
+) -> HashMap<Ident, Vec<TraitBound>> {
+ // Add trait bounds provided at the declaration site of type parameters for the struct/enum.
+ let mut param_constraint_mapping: HashMap<Ident, Vec<TraitBound>> = type_params
+ .iter()
+ .map(|type_param| {
+ let trait_bounds: Vec<TraitBound> = type_param
+ .bounds
+ .iter()
+ .flat_map(|bound| match bound {
+ TypeParamBound::Trait(trait_bound) => Some(trait_bound),
+ _ => None,
+ })
+ .cloned()
+ .collect();
+ (type_param.ident.clone(), trait_bounds)
+ })
+ .collect();
+
+ // Add trait bounds from `where` clauses, which may be type parameters or types containing
+ // those parameters.
+ for predicate in where_clause.predicates.iter() {
+ // We only care about type and not lifetime constraints here.
+ if let WherePredicate::Type(ref pred_ty) = predicate {
+ let ident = match &pred_ty.bounded_ty {
+ Type::Path(TypePath { path, qself: None }) => match path.get_ident() {
+ None => continue,
+ Some(ident) => ident,
+ },
+ _ => continue,
+ };
+ // We ignore any type constraints that aren't direct references to type
+ // parameters of the current enum of struct definition. No types can be
+ // constrained in a `where` clause unless they are a type parameter or a generic
+ // type instantiated with one of the type parameters, so by only allowing single
+ // identifiers, we can be sure that the constrained type is a type parameter
+ // that is contained in `param_constraint_mapping`.
+ if let Some((_, ref mut known_bounds)) = param_constraint_mapping
+ .iter_mut()
+ .find(|(id, _)| *id == ident)
+ {
+ for bound in pred_ty.bounds.iter() {
+ // We only care about trait bounds here.
+ if let TypeParamBound::Trait(ref bound) = bound {
+ known_bounds.push(bound.clone());
+ }
+ }
+ }
+ }
+ }
+
+ param_constraint_mapping
+}
+
+/// Hygienically add `where _: Display` to the set of [TypeParamBound]s for `ident`, creating such
+/// a set if necessary.
+fn ensure_display_in_where_clause_for_type(where_clause: &mut WhereClause, ident: Ident) {
+ for pred_ty in where_clause
+ .predicates
+ .iter_mut()
+ // Find the `where` predicate constraining the current type param, if it exists.
+ .flat_map(|predicate| match predicate {
+ WherePredicate::Type(pred_ty) => Some(pred_ty),
+ // We're looking through type constraints, not lifetime constraints.
+ _ => None,
+ })
+ {
+ // Do a complicated destructuring in order to check if the type being constrained in this
+ // `where` clause is the type we're looking for, so we can use the mutable reference to
+ // `pred_ty` if so.
+ let matches_desired_type = matches!(
+ &pred_ty.bounded_ty,
+ Type::Path(TypePath { path, .. }) if Some(&ident) == path.get_ident());
+ if matches_desired_type {
+ add_display_constraint_to_type_predicate(pred_ty);
+ return;
+ }
+ }
+
+ // If there is no `where` predicate for the current type param, we will construct one.
+ let mut new_type_predicate = new_empty_where_type_predicate(ident);
+ add_display_constraint_to_type_predicate(&mut new_type_predicate);
+ append_where_clause_type_predicate(where_clause, new_type_predicate);
+}
+
+/// For all declared type parameters, add a [core::fmt::Display] constraint, unless the type
+/// parameter already has any type constraint.
+fn ensure_where_clause_has_display_for_all_unconstrained_members(
+ where_clause: &mut WhereClause,
+ type_params: &[&TypeParam],
+) {
+ let param_constraint_mapping = extract_trait_constraints_from_source(where_clause, type_params);
+
+ for (ident, known_bounds) in param_constraint_mapping.into_iter() {
+ // If the type parameter has any constraints already, we don't want to touch it, to avoid
+ // breaking use cases where a type parameter only needs to impl `Debug`, for example.
+ if known_bounds.is_empty() {
+ ensure_display_in_where_clause_for_type(where_clause, ident);
+ }
+ }
+}
+
+/// Generate a `where` clause that ensures all generic type parameters `impl`
+/// [core::fmt::Display] unless already constrained.
+///
+/// This approach allows struct/enum definitions deriving [crate::Display] to avoid hardcoding
+/// a [core::fmt::Display] constraint into every type parameter.
+///
+/// If the type parameter isn't already constrained, we add a `where _: Display` clause to our
+/// display implementation to expect to be able to format every enum case or struct member.
+///
+/// In fact, we would preferably only require `where _: Display` or `where _: Debug` where the
+/// format string actually requires it. However, while [`std::fmt` defines a formal syntax for
+/// `format!()`][format syntax], it *doesn't* expose the actual logic to parse the format string,
+/// which appears to live in [`rustc_parse_format`]. While we use the [`syn`] crate to parse rust
+/// syntax, it also doesn't currently provide any method to introspect a `format!()` string. It
+/// would be nice to contribute this upstream in [`syn`].
+///
+/// [format syntax]: std::fmt#syntax
+/// [`rustc_parse_format`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_parse_format/index.html
+fn generate_where_clause(generics: &Generics, where_clause: Option<&WhereClause>) -> WhereClause {
+ let mut where_clause = where_clause.cloned().unwrap_or_else(new_empty_where_clause);
+ let type_params: Vec<&TypeParam> = generics.type_params().collect();
+ ensure_where_clause_has_display_for_all_unconstrained_members(&mut where_clause, &type_params);
+ where_clause
+}
+
+fn impl_enum(input: &DeriveInput, data: &DataEnum) -> Result<TokenStream> {
+ let ty = &input.ident;
+ let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
+ let where_clause = generate_where_clause(&input.generics, where_clause);
+
+ let helper = AttrsHelper::new(&input.attrs);
+
+ let displays = data
+ .variants
+ .iter()
+ .map(|variant| helper.display_with_input(&input.attrs, &variant.attrs))
+ .collect::<Result<Vec<_>>>()?;
+
+ if data.variants.is_empty() {
+ Ok(quote! {
+ impl #impl_generics core::fmt::Display for #ty #ty_generics #where_clause {
+ fn fmt(&self, formatter: &mut core::fmt::Formatter) -> core::fmt::Result {
+ unreachable!("empty enums cannot be instantiated and thus cannot be printed")
+ }
+ }
+ })
+ } else if displays.iter().any(Option::is_some) {
+ let arms = data
+ .variants
+ .iter()
+ .zip(displays)
+ .map(|(variant, display)| {
+ let display =
+ display.ok_or_else(|| Error::new_spanned(variant, "missing doc comment"))?;
+ let ident = &variant.ident;
+ Ok(match &variant.fields {
+ Fields::Named(fields) => {
+ let var = fields.named.iter().map(|field| &field.ident);
+ quote!(Self::#ident { #(#var),* } => { #display })
+ }
+ Fields::Unnamed(fields) => {
+ let var = (0..fields.unnamed.len()).map(|i| format_ident!("_{}", i));
+ quote!(Self::#ident(#(#var),*) => { #display })
+ }
+ Fields::Unit => quote!(Self::#ident => { #display }),
+ })
+ })
+ .collect::<Result<Vec<_>>>()?;
+ Ok(quote! {
+ impl #impl_generics core::fmt::Display for #ty #ty_generics #where_clause {
+ fn fmt(&self, formatter: &mut core::fmt::Formatter) -> core::fmt::Result {
+ #[allow(unused_variables)]
+ match self {
+ #(#arms,)*
+ }
+ }
+ }
+ })
+ } else {
+ Err(Error::new_spanned(input, "Missing doc comments"))
+ }
+}
diff --git a/third_party/rust/displaydoc/src/fmt.rs b/third_party/rust/displaydoc/src/fmt.rs new file mode 100644 index 0000000000..3334a82ff2 --- /dev/null +++ b/third_party/rust/displaydoc/src/fmt.rs @@ -0,0 +1,159 @@ +use crate::attr::Display;
+use proc_macro2::TokenStream;
+use quote::quote_spanned;
+use syn::{Ident, LitStr};
+
+macro_rules! peek_next {
+ ($read:ident) => {
+ match $read.chars().next() {
+ Some(next) => next,
+ None => return,
+ }
+ };
+}
+
+impl Display {
+ // Transform `"error {var}"` to `"error {}", var`.
+ pub(crate) fn expand_shorthand(&mut self) {
+ let span = self.fmt.span();
+ let fmt = self.fmt.value();
+ let mut read = fmt.as_str();
+ let mut out = String::new();
+ let mut args = TokenStream::new();
+
+ while let Some(brace) = read.find('{') {
+ out += &read[..=brace];
+ read = &read[brace + 1..];
+
+ // skip cases where we find a {{
+ if read.starts_with('{') {
+ out.push('{');
+ read = &read[1..];
+ continue;
+ }
+
+ let next = peek_next!(read);
+
+ let var = match next {
+ '0'..='9' => take_int(&mut read),
+ 'a'..='z' | 'A'..='Z' | '_' => take_ident(&mut read),
+ _ => return,
+ };
+
+ let ident = Ident::new(&var, span);
+
+ let next = peek_next!(read);
+
+ let arg = if cfg!(feature = "std") && next == '}' {
+ quote_spanned!(span=> , #ident.__displaydoc_display())
+ } else {
+ quote_spanned!(span=> , #ident)
+ };
+
+ args.extend(arg);
+ }
+
+ out += read;
+ self.fmt = LitStr::new(&out, self.fmt.span());
+ self.args = args;
+ }
+}
+
+fn take_int(read: &mut &str) -> String {
+ let mut int = String::new();
+ int.push('_');
+ for (i, ch) in read.char_indices() {
+ match ch {
+ '0'..='9' => int.push(ch),
+ _ => {
+ *read = &read[i..];
+ break;
+ }
+ }
+ }
+ int
+}
+
+fn take_ident(read: &mut &str) -> String {
+ let mut ident = String::new();
+ for (i, ch) in read.char_indices() {
+ match ch {
+ 'a'..='z' | 'A'..='Z' | '0'..='9' | '_' => ident.push(ch),
+ _ => {
+ *read = &read[i..];
+ break;
+ }
+ }
+ }
+ ident
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+ use pretty_assertions::assert_eq;
+ use proc_macro2::Span;
+
+ fn assert(input: &str, fmt: &str, args: &str) {
+ let mut display = Display {
+ fmt: LitStr::new(input, Span::call_site()),
+ args: TokenStream::new(),
+ };
+ display.expand_shorthand();
+ assert_eq!(fmt, display.fmt.value());
+ assert_eq!(args, display.args.to_string());
+ }
+
+ #[test]
+ fn test_expand() {
+ assert("fn main() {{ }}", "fn main() {{ }}", "");
+ }
+
+ #[test]
+ #[cfg_attr(not(feature = "std"), ignore)]
+ fn test_std_expand() {
+ assert(
+ "{v} {v:?} {0} {0:?}",
+ "{} {:?} {} {:?}",
+ ", v . __displaydoc_display () , v , _0 . __displaydoc_display () , _0",
+ );
+ assert("error {var}", "error {}", ", var . __displaydoc_display ()");
+
+ assert(
+ "error {var1}",
+ "error {}",
+ ", var1 . __displaydoc_display ()",
+ );
+
+ assert(
+ "error {var1var}",
+ "error {}",
+ ", var1var . __displaydoc_display ()",
+ );
+
+ assert(
+ "The path {0}",
+ "The path {}",
+ ", _0 . __displaydoc_display ()",
+ );
+ assert("The path {0:?}", "The path {:?}", ", _0");
+ }
+
+ #[test]
+ #[cfg_attr(feature = "std", ignore)]
+ fn test_nostd_expand() {
+ assert(
+ "{v} {v:?} {0} {0:?}",
+ "{} {:?} {} {:?}",
+ ", v , v , _0 , _0",
+ );
+ assert("error {var}", "error {}", ", var");
+
+ assert("The path {0}", "The path {}", ", _0");
+ assert("The path {0:?}", "The path {:?}", ", _0");
+
+ assert("error {var1}", "error {}", ", var1");
+
+ assert("error {var1var}", "error {}", ", var1var");
+ }
+}
diff --git a/third_party/rust/displaydoc/src/lib.rs b/third_party/rust/displaydoc/src/lib.rs new file mode 100644 index 0000000000..e4653d6755 --- /dev/null +++ b/third_party/rust/displaydoc/src/lib.rs @@ -0,0 +1,187 @@ +//! This library provides a convenient derive macro for the standard library's
+//! [`core::fmt::Display`] trait.
+//!
+//! [`core::fmt::Display`]: https://doc.rust-lang.org/std/fmt/trait.Display.html
+//!
+//! ```toml
+//! [dependencies]
+//! displaydoc = "0.2"
+//! ```
+//!
+//! *Compiler support: requires rustc 1.56+*
+//!
+//! <br>
+//!
+//! ## Example
+//!
+//! *Demonstration alongside the [`Error`][std::error::Error] derive macro from [`thiserror`](https://docs.rs/thiserror/1.0.25/thiserror/index.html),
+//! to propagate source locations from [`io::Error`][std::io::Error] with the `#[source]` attribute:*
+//! ```rust
+//! use std::io;
+//! use displaydoc::Display;
+//! use thiserror::Error;
+//!
+//! #[derive(Display, Error, Debug)]
+//! pub enum DataStoreError {
+//! /// data store disconnected
+//! Disconnect(#[source] io::Error),
+//! /// the data for key `{0}` is not available
+//! Redaction(String),
+//! /// invalid header (expected {expected:?}, found {found:?})
+//! InvalidHeader {
+//! expected: String,
+//! found: String,
+//! },
+//! /// unknown data store error
+//! Unknown,
+//! }
+//!
+//! let error = DataStoreError::Redaction("CLASSIFIED CONTENT".to_string());
+//! assert!("the data for key `CLASSIFIED CONTENT` is not available" == &format!("{}", error));
+//! ```
+//! *Note that although [`io::Error`][std::io::Error] implements `Display`, we do not add it to the
+//! generated message for `DataStoreError::Disconnect`, since it is already made available via
+//! `#[source]`. See further context on avoiding duplication in error reports at the rust blog
+//! [here](https://github.com/yaahc/blog.rust-lang.org/blob/master/posts/inside-rust/2021-05-15-What-the-error-handling-project-group-is-working-towards.md#duplicate-information-issue).*
+//!
+//! <br>
+//!
+//! ## Details
+//!
+//! - A `fmt::Display` impl is generated for your enum if you provide
+//! a docstring comment on each variant as shown above in the example. The
+//! `Display` derive macro supports a shorthand for interpolating fields from
+//! the error:
+//! - `/// {var}` ⟶ `write!("{}", self.var)`
+//! - `/// {0}` ⟶ `write!("{}", self.0)`
+//! - `/// {var:?}` ⟶ `write!("{:?}", self.var)`
+//! - `/// {0:?}` ⟶ `write!("{:?}", self.0)`
+//! - This also works with structs and [generic types][crate::Display#generic-type-parameters]:
+//! ```rust
+//! # use displaydoc::Display;
+//! /// oh no, an error: {0}
+//! #[derive(Display)]
+//! pub struct Error<E>(pub E);
+//!
+//! let error: Error<&str> = Error("muahaha i am an error");
+//! assert!("oh no, an error: muahaha i am an error" == &format!("{}", error));
+//! ```
+//!
+//! - Two optional attributes can be added to your types next to the derive:
+//!
+//! - `#[ignore_extra_doc_attributes]` makes the macro ignore any doc
+//! comment attributes (or `///` lines) after the first. Multi-line
+//! comments using `///` are otherwise treated as an error, so use this
+//! attribute or consider switching to block doc comments (`/** */`).
+//!
+//! - `#[prefix_enum_doc_attributes]` combines the doc comment message on
+//! your enum itself with the messages for each variant, in the format
+//! “enum: variant”. When added to an enum, the doc comment on the enum
+//! becomes mandatory. When added to any other type, it has no effect.
+//!
+//! - In case you want to have an independent doc comment, the
+//! `#[displaydoc("...")` atrribute may be used on the variant or struct to
+//! override it.
+//!
+//! <br>
+//!
+//! ## FAQ
+//!
+//! 1. **Is this crate `no_std` compatible?**
+//! * Yes! This crate implements the [`core::fmt::Display`] trait, not the [`std::fmt::Display`] trait, so it should work in `std` and `no_std` environments. Just add `default-features = false`.
+//!
+//! 2. **Does this crate work with `Path` and `PathBuf` via the `Display` trait?**
+//! * Yuuup. This crate uses @dtolnay's [autoref specialization technique](https://github.com/dtolnay/case-studies/blob/master/autoref-specialization/README.md) to add a special trait for types to get the display impl. It then specializes for `Path` and `PathBuf`, and when either of these types are found, it calls `self.display()` to get a `std::path::Display<'_>` type which can be used with the `Display` format specifier!
+#![doc(html_root_url = "https://docs.rs/displaydoc/0.2.3")]
+#![cfg_attr(docsrs, feature(doc_cfg))]
+#![warn(
+ rust_2018_idioms,
+ unreachable_pub,
+ bad_style,
+ dead_code,
+ improper_ctypes,
+ non_shorthand_field_patterns,
+ no_mangle_generic_items,
+ overflowing_literals,
+ path_statements,
+ patterns_in_fns_without_body,
+ private_in_public,
+ unconditional_recursion,
+ unused,
+ unused_allocation,
+ unused_comparisons,
+ unused_parens,
+ while_true
+)]
+#![allow(clippy::try_err)]
+
+#[allow(unused_extern_crates)]
+extern crate proc_macro;
+
+mod attr;
+mod expand;
+mod fmt;
+
+use proc_macro::TokenStream;
+use syn::{parse_macro_input, DeriveInput};
+
+/// [Custom `#[derive(...)]` macro](https://doc.rust-lang.org/edition-guide/rust-2018/macros/custom-derive.html)
+/// for implementing [`fmt::Display`][core::fmt::Display] via doc comment attributes.
+///
+/// ### Generic Type Parameters
+///
+/// Type parameters to an enum or struct using this macro should *not* need to
+/// have an explicit `Display` constraint at the struct or enum definition
+/// site. A `Display` implementation for the `derive`d struct or enum is
+/// generated assuming each type parameter implements `Display`, but that should
+/// be possible without adding the constraint to the struct definition itself:
+/// ```rust
+/// use displaydoc::Display;
+///
+/// /// oh no, an error: {0}
+/// #[derive(Display)]
+/// pub struct Error<E>(pub E);
+///
+/// // No need to require `E: Display`, since `displaydoc::Display` adds that implicitly.
+/// fn generate_error<E>(e: E) -> Error<E> { Error(e) }
+///
+/// assert!("oh no, an error: muahaha" == &format!("{}", generate_error("muahaha")));
+/// ```
+///
+/// ### Using [`Debug`][core::fmt::Debug] Implementations with Type Parameters
+/// However, if a type parameter must instead be constrained with the
+/// [`Debug`][core::fmt::Debug] trait so that some field may be printed with
+/// `{:?}`, that constraint must currently still also be specified redundantly
+/// at the struct or enum definition site. If a struct or enum field is being
+/// formatted with `{:?}` via [`displaydoc`][crate], and a generic type
+/// parameter must implement `Debug` to do that, then that struct or enum
+/// definition will need to propagate the `Debug` constraint to every type
+/// parameter it's instantiated with:
+/// ```rust
+/// use core::fmt::Debug;
+/// use displaydoc::Display;
+///
+/// /// oh no, an error: {0:?}
+/// #[derive(Display)]
+/// pub struct Error<E: Debug>(pub E);
+///
+/// // `E: Debug` now has to propagate to callers.
+/// fn generate_error<E: Debug>(e: E) -> Error<E> { Error(e) }
+///
+/// assert!("oh no, an error: \"cool\"" == &format!("{}", generate_error("cool")));
+///
+/// // Try this with a struct that doesn't impl `Display` at all, unlike `str`.
+/// #[derive(Debug)]
+/// pub struct Oh;
+/// assert!("oh no, an error: Oh" == &format!("{}", generate_error(Oh)));
+/// ```
+#[proc_macro_derive(
+ Display,
+ attributes(ignore_extra_doc_attributes, prefix_enum_doc_attributes, displaydoc)
+)]
+pub fn derive_error(input: TokenStream) -> TokenStream {
+ let input = parse_macro_input!(input as DeriveInput);
+ expand::derive(&input)
+ .unwrap_or_else(|err| err.to_compile_error())
+ .into()
+}
|