Introduce Diagnostic trait (#14130)

crates/red_knot_python_semantic/src/types.rs

@@ -37,9 +37,12 @@ mod mro;
 mod narrow;
 mod unpacker;
 
+#[salsa::tracked(return_ref)]
 pub fn check_types(db: &dyn Db, file: File) -> TypeCheckDiagnostics {
     let _span = tracing::trace_span!("check_types", file=?file.path(db)).entered();
 
+    tracing::debug!("Checking file '{path}'", path = file.path(db));
+
     let index = semantic_index(db, file);
     let mut diagnostics = TypeCheckDiagnostics::new();
 

crates/red_knot_python_semantic/src/types/diagnostic.rs

@@ -1,13 +1,14 @@
+use crate::types::{ClassLiteralType, Type};
+use crate::Db;
+use ruff_db::diagnostic::{Diagnostic, Severity};
 use ruff_db::files::File;
 use ruff_python_ast::{self as ast, AnyNodeRef};
 use ruff_text_size::{Ranged, TextRange};
+use std::borrow::Cow;
 use std::fmt::Formatter;
 use std::ops::Deref;
 use std::sync::Arc;
 
-use crate::types::{ClassLiteralType, Type};
-use crate::Db;
-
 #[derive(Debug, Eq, PartialEq, Clone)]
 pub struct TypeCheckDiagnostic {
     // TODO: Don't use string keys for rules
@@ -31,6 +32,28 @@ impl TypeCheckDiagnostic {
     }
 }
 
+impl Diagnostic for TypeCheckDiagnostic {
+    fn rule(&self) -> &str {
+        TypeCheckDiagnostic::rule(self)
+    }
+
+    fn message(&self) -> Cow<str> {
+        TypeCheckDiagnostic::message(self).into()
+    }
+
+    fn file(&self) -> File {
+        TypeCheckDiagnostic::file(self)
+    }
+
+    fn range(&self) -> Option<TextRange> {
+        Some(Ranged::range(self))
+    }
+
+    fn severity(&self) -> Severity {
+        Severity::Error
+    }
+}
+
 impl Ranged for TypeCheckDiagnostic {
     fn range(&self) -> TextRange {
         self.range

crates/red_knot_python_semantic/src/types/infer.rs

@@ -4533,7 +4533,7 @@ mod tests {
         let file = system_path_to_file(db, filename).unwrap();
         let diagnostics = check_types(db, file);
 
-        assert_diagnostic_messages(&diagnostics, expected);
+        assert_diagnostic_messages(diagnostics, expected);
     }
 
     #[test]