1 files changed, 77 insertions, 0 deletions
diff --git a/src/tools/rust-analyzer/xtask/src/codegen/diagnostics_docs.rs b/src/tools/rust-analyzer/xtask/src/codegen/diagnostics_docs.rs
new file mode 100644
index 00000000000..cf30531e7f9
--- /dev/null
+++ b/src/tools/rust-analyzer/xtask/src/codegen/diagnostics_docs.rs
@@ -0,0 +1,77 @@
+//! Generates `assists.md` documentation.
+
+use std::{fmt, fs, io, path::PathBuf};
+
+use crate::{
+    codegen::{add_preamble, list_rust_files, CommentBlock, Location},
+    project_root,
+};
+
+pub(crate) fn generate(check: bool) {
+    let diagnostics = Diagnostic::collect().unwrap();
+    if !check {
+        let contents =
+            diagnostics.into_iter().map(|it| it.to_string()).collect::<Vec<_>>().join("\n\n");
+        let contents = add_preamble("sourcegen_diagnostic_docs", contents);
+        let dst = project_root().join("docs/user/generated_diagnostic.adoc");
+        fs::write(dst, contents).unwrap();
+    }
+}
+
+#[derive(Debug)]
+struct Diagnostic {
+    id: String,
+    location: Location,
+    doc: String,
+}
+
+impl Diagnostic {
+    fn collect() -> io::Result<Vec<Diagnostic>> {
+        let handlers_dir = project_root().join("crates/ide-diagnostics/src/handlers");
+
+        let mut res = Vec::new();
+        for path in list_rust_files(&handlers_dir) {
+            collect_file(&mut res, path)?;
+        }
+        res.sort_by(|lhs, rhs| lhs.id.cmp(&rhs.id));
+        return Ok(res);
+
+        fn collect_file(acc: &mut Vec<Diagnostic>, path: PathBuf) -> io::Result<()> {
+            let text = fs::read_to_string(&path)?;
+            let comment_blocks = CommentBlock::extract("Diagnostic", &text);
+
+            for block in comment_blocks {
+                let id = block.id;
+                if let Err(msg) = is_valid_diagnostic_name(&id) {
+                    panic!("invalid diagnostic name: {id:?}:\n  {msg}")
+                }
+                let doc = block.contents.join("\n");
+                let location = Location { file: path.clone(), line: block.line };
+                acc.push(Diagnostic { id, location, doc })
+            }
+
+            Ok(())
+        }
+    }
+}
+
+fn is_valid_diagnostic_name(diagnostic: &str) -> Result<(), String> {
+    let diagnostic = diagnostic.trim();
+    if diagnostic.find(char::is_whitespace).is_some() {
+        return Err("Diagnostic names can't contain whitespace symbols".into());
+    }
+    if diagnostic.chars().any(|c| c.is_ascii_uppercase()) {
+        return Err("Diagnostic names can't contain uppercase symbols".into());
+    }
+    if diagnostic.chars().any(|c| !c.is_ascii()) {
+        return Err("Diagnostic can't contain non-ASCII symbols".into());
+    }
+
+    Ok(())
+}
+
+impl fmt::Display for Diagnostic {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        writeln!(f, "=== {}\n**Source:** {}\n{}", self.id, self.location, self.doc)
+    }
+}