1 files changed, 189 insertions, 0 deletions
diff --git a/third_party/rust/bindgen/diagnostics.rs b/third_party/rust/bindgen/diagnostics.rs
new file mode 100644
index 0000000000..f765afe970
--- /dev/null
+++ b/third_party/rust/bindgen/diagnostics.rs
@@ -0,0 +1,189 @@
+//! Types and function used to emit pretty diagnostics for `bindgen`.
+//!
+//! The entry point of this module is the [`Diagnostic`] type.
+
+use std::fmt::Write;
+use std::io::{self, BufRead, BufReader};
+use std::{borrow::Cow, fs::File};
+
+use annotate_snippets::{
+    display_list::{DisplayList, FormatOptions},
+    snippet::{Annotation, Slice as ExtSlice, Snippet},
+};
+
+use annotate_snippets::snippet::AnnotationType;
+
+#[derive(Clone, Copy, Debug)]
+pub(crate) enum Level {
+    Error,
+    Warn,
+    Info,
+    Note,
+    Help,
+}
+
+impl From<Level> for AnnotationType {
+    fn from(level: Level) -> Self {
+        match level {
+            Level::Error => Self::Error,
+            Level::Warn => Self::Warning,
+            Level::Info => Self::Info,
+            Level::Note => Self::Note,
+            Level::Help => Self::Help,
+        }
+    }
+}
+
+/// A `bindgen` diagnostic.
+#[derive(Default)]
+pub(crate) struct Diagnostic<'a> {
+    title: Option<(Cow<'a, str>, Level)>,
+    slices: Vec<Slice<'a>>,
+    footer: Vec<(Cow<'a, str>, Level)>,
+}
+
+impl<'a> Diagnostic<'a> {
+    /// Add a title to the diagnostic and set its type.
+    pub(crate) fn with_title(
+        &mut self,
+        title: impl Into<Cow<'a, str>>,
+        level: Level,
+    ) -> &mut Self {
+        self.title = Some((title.into(), level));
+        self
+    }
+
+    /// Add a slice of source code to the diagnostic.
+    pub(crate) fn add_slice(&mut self, slice: Slice<'a>) -> &mut Self {
+        self.slices.push(slice);
+        self
+    }
+
+    /// Add a footer annotation to the diagnostic. This annotation will have its own type.
+    pub(crate) fn add_annotation(
+        &mut self,
+        msg: impl Into<Cow<'a, str>>,
+        level: Level,
+    ) -> &mut Self {
+        self.footer.push((msg.into(), level));
+        self
+    }
+
+    /// Print this diagnostic.
+    ///
+    /// The diagnostic is printed using `cargo:warning` if `bindgen` is being invoked by a build
+    /// script or using `eprintln` otherwise.
+    pub(crate) fn display(&self) {
+        std::thread_local! {
+            static INVOKED_BY_BUILD_SCRIPT: bool =  std::env::var_os("CARGO_CFG_TARGET_ARCH").is_some();
+        }
+
+        let mut title = None;
+        let mut footer = vec![];
+        let mut slices = vec![];
+        if let Some((msg, level)) = &self.title {
+            title = Some(Annotation {
+                id: Some("bindgen"),
+                label: Some(msg.as_ref()),
+                annotation_type: (*level).into(),
+            })
+        }
+
+        for (msg, level) in &self.footer {
+            footer.push(Annotation {
+                id: None,
+                label: Some(msg.as_ref()),
+                annotation_type: (*level).into(),
+            });
+        }
+
+        // add additional info that this is generated by bindgen
+        // so as to not confuse with rustc warnings
+        footer.push(Annotation {
+            id: None,
+            label: Some("This diagnostic was generated by bindgen."),
+            annotation_type: AnnotationType::Info,
+        });
+
+        for slice in &self.slices {
+            if let Some(source) = &slice.source {
+                slices.push(ExtSlice {
+                    source: source.as_ref(),
+                    line_start: slice.line.unwrap_or_default(),
+                    origin: slice.filename.as_deref(),
+                    annotations: vec![],
+                    fold: false,
+                })
+            }
+        }
+
+        let snippet = Snippet {
+            title,
+            footer,
+            slices,
+            opt: FormatOptions {
+                color: true,
+                ..Default::default()
+            },
+        };
+        let dl = DisplayList::from(snippet);
+
+        if INVOKED_BY_BUILD_SCRIPT.with(Clone::clone) {
+            // This is just a hack which hides the `warning:` added by cargo at the beginning of
+            // every line. This should be fine as our diagnostics already have a colorful title.
+            // FIXME (pvdrz): Could it be that this doesn't work in other languages?
+            let hide_warning = "\r        \r";
+            let string = dl.to_string();
+            for line in string.lines() {
+                println!("cargo:warning={}{}", hide_warning, line);
+            }
+        } else {
+            eprintln!("{}\n", dl);
+        }
+    }
+}
+
+/// A slice of source code.
+#[derive(Default)]
+pub(crate) struct Slice<'a> {
+    source: Option<Cow<'a, str>>,
+    filename: Option<String>,
+    line: Option<usize>,
+}
+
+impl<'a> Slice<'a> {
+    /// Set the source code.
+    pub(crate) fn with_source(
+        &mut self,
+        source: impl Into<Cow<'a, str>>,
+    ) -> &mut Self {
+        self.source = Some(source.into());
+        self
+    }
+
+    /// Set the file, line and column.
+    pub(crate) fn with_location(
+        &mut self,
+        mut name: String,
+        line: usize,
+        col: usize,
+    ) -> &mut Self {
+        write!(name, ":{}:{}", line, col)
+            .expect("Writing to a string cannot fail");
+        self.filename = Some(name);
+        self.line = Some(line);
+        self
+    }
+}
+
+pub(crate) fn get_line(
+    filename: &str,
+    line: usize,
+) -> io::Result<Option<String>> {
+    let file = BufReader::new(File::open(filename)?);
+    if let Some(line) = file.lines().nth(line.wrapping_sub(1)) {
+        return line.map(Some);
+    }
+
+    Ok(None)
+}