red_knot: use Diagnostic inside of red knot

This replaces things like `TypeCheckDiagnostic` with the new Diagnostic`
type.

This is a "surgical" replacement where we retain the existing API of
of diagnostic reporting such that _most_ of Red Knot doesn't need to be
changed to support this update. But it will enable us to start using the
new diagnostic renderer and to delete the old renderer. It also paves
the path for exposing the new `Diagnostic` data model to the broader Red
Knot codebase.

crates/red_knot_project/src/lib.rs

@@ -9,7 +9,9 @@ pub use metadata::{ProjectDiscoveryError, ProjectMetadata};
 use red_knot_python_semantic::lint::{LintRegistry, LintRegistryBuilder, RuleSelection};
 use red_knot_python_semantic::register_lints;
 use red_knot_python_semantic::types::check_types;
-use ruff_db::diagnostic::{DiagnosticId, OldDiagnosticTrait, OldParseDiagnostic, Severity, Span};
+use ruff_db::diagnostic::{
+    create_parse_diagnostic, Annotation, Diagnostic, DiagnosticId, Severity, Span,
+};
 use ruff_db::files::File;
 use ruff_db::parsed::parsed_module;
 use ruff_db::source::{source_text, SourceTextError};
@@ -17,7 +19,6 @@ use ruff_db::system::{SystemPath, SystemPathBuf};
 use rustc_hash::FxHashSet;
 use salsa::Durability;
 use salsa::Setter;
-use std::borrow::Cow;
 use std::sync::Arc;
 use thiserror::Error;
 
@@ -163,24 +164,27 @@ impl Project {
     }
 
     /// Checks all open files in the project and its dependencies.
-    pub(crate) fn check(self, db: &ProjectDatabase) -> Vec<Box<dyn OldDiagnosticTrait>> {
+    pub(crate) fn check(self, db: &ProjectDatabase) -> Vec<Diagnostic> {
         let project_span = tracing::debug_span!("Project::check");
         let _span = project_span.enter();
 
         tracing::debug!("Checking project '{name}'", name = self.name(db));
 
-        let mut diagnostics: Vec<Box<dyn OldDiagnosticTrait>> = Vec::new();
-        diagnostics.extend(self.settings_diagnostics(db).iter().map(|diagnostic| {
-            let diagnostic: Box<dyn OldDiagnosticTrait> = Box::new(diagnostic.clone());
-            diagnostic
-        }));
+        let mut diagnostics: Vec<Diagnostic> = Vec::new();
+        diagnostics.extend(
+            self.settings_diagnostics(db)
+                .iter()
+                .map(OptionDiagnostic::to_diagnostic),
+        );
 
         let files = ProjectFiles::new(db, self);
 
-        diagnostics.extend(files.diagnostics().iter().cloned().map(|diagnostic| {
-            let diagnostic: Box<dyn OldDiagnosticTrait> = Box::new(diagnostic);
-            diagnostic
-        }));
+        diagnostics.extend(
+            files
+                .diagnostics()
+                .iter()
+                .map(IOErrorDiagnostic::to_diagnostic),
+        );
 
         let result = Arc::new(std::sync::Mutex::new(diagnostics));
         let inner_result = Arc::clone(&result);
@@ -208,14 +212,11 @@ impl Project {
         Arc::into_inner(result).unwrap().into_inner().unwrap()
     }
 
-    pub(crate) fn check_file(self, db: &dyn Db, file: File) -> Vec<Box<dyn OldDiagnosticTrait>> {
+    pub(crate) fn check_file(self, db: &dyn Db, file: File) -> Vec<Diagnostic> {
         let mut file_diagnostics: Vec<_> = self
             .settings_diagnostics(db)
             .iter()
-            .map(|diagnostic| {
-                let diagnostic: Box<dyn OldDiagnosticTrait> = Box::new(diagnostic.clone());
-                diagnostic
-            })
+            .map(OptionDiagnostic::to_diagnostic)
             .collect();
 
         let check_diagnostics = check_file_impl(db, file);
@@ -398,35 +399,36 @@ impl Project {
     }
 }
 
-fn check_file_impl(db: &dyn Db, file: File) -> Vec<Box<dyn OldDiagnosticTrait>> {
-    let mut diagnostics: Vec<Box<dyn OldDiagnosticTrait>> = Vec::new();
+fn check_file_impl(db: &dyn Db, file: File) -> Vec<Diagnostic> {
+    let mut diagnostics: Vec<Diagnostic> = Vec::new();
 
     // Abort checking if there are IO errors.
     let source = source_text(db.upcast(), file);
 
     if let Some(read_error) = source.read_error() {
-        diagnostics.push(Box::new(IOErrorDiagnostic {
-            file: Some(file),
-            error: read_error.clone().into(),
-        }));
+        diagnostics.push(
+            IOErrorDiagnostic {
+                file: Some(file),
+                error: read_error.clone().into(),
+            }
+            .to_diagnostic(),
+        );
         return diagnostics;
     }
 
     let parsed = parsed_module(db.upcast(), file);
-    diagnostics.extend(parsed.errors().iter().map(|error| {
-        let diagnostic: Box<dyn OldDiagnosticTrait> =
-            Box::new(OldParseDiagnostic::new(file, error.clone()));
-        diagnostic
-    }));
+    diagnostics.extend(
+        parsed
+            .errors()
+            .iter()
+            .map(|error| create_parse_diagnostic(file, error)),
+    );
 
-    diagnostics.extend(check_types(db.upcast(), file).iter().map(|diagnostic| {
-        let boxed: Box<dyn OldDiagnosticTrait> = Box::new(diagnostic.clone());
-        boxed
-    }));
+    diagnostics.extend(check_types(db.upcast(), file).into_iter().cloned());
 
     diagnostics.sort_unstable_by_key(|diagnostic| {
         diagnostic
-            .span()
+            .primary_span()
             .and_then(|span| span.range())
             .unwrap_or_default()
             .start()
@@ -494,21 +496,13 @@ pub struct IOErrorDiagnostic {
     error: IOErrorKind,
 }
 
-impl OldDiagnosticTrait for IOErrorDiagnostic {
-    fn id(&self) -> DiagnosticId {
-        DiagnosticId::Io
-    }
-
-    fn message(&self) -> Cow<str> {
-        self.error.to_string().into()
-    }
-
-    fn span(&self) -> Option<Span> {
-        self.file.map(Span::from)
-    }
-
-    fn severity(&self) -> Severity {
-        Severity::Error
+impl IOErrorDiagnostic {
+    fn to_diagnostic(&self) -> Diagnostic {
+        let mut diag = Diagnostic::new(DiagnosticId::Io, Severity::Error, &self.error);
+        if let Some(file) = self.file {
+            diag.annotate(Annotation::primary(Span::from(file)));
+        }
+        diag
     }
 }
 
@@ -526,7 +520,6 @@ mod tests {
     use crate::db::tests::TestDb;
     use crate::{check_file_impl, ProjectMetadata};
     use red_knot_python_semantic::types::check_types;
-    use ruff_db::diagnostic::OldDiagnosticTrait;
     use ruff_db::files::system_path_to_file;
     use ruff_db::source::source_text;
     use ruff_db::system::{DbWithTestSystem, DbWithWritableSystem as _, SystemPath, SystemPathBuf};
@@ -550,7 +543,7 @@ mod tests {
         assert_eq!(
             check_file_impl(&db, file)
                 .into_iter()
-                .map(|diagnostic| diagnostic.message().into_owned())
+                .map(|diagnostic| diagnostic.primary_message().to_string())
                 .collect::<Vec<_>>(),
             vec!["Failed to read file: No such file or directory".to_string()]
         );
@@ -566,7 +559,7 @@ mod tests {
         assert_eq!(
             check_file_impl(&db, file)
                 .into_iter()
-                .map(|diagnostic| diagnostic.message().into_owned())
+                .map(|diagnostic| diagnostic.primary_message().to_string())
                 .collect::<Vec<_>>(),
             vec![] as Vec<String>
         );