red_knot_python_semantic: remove `WithDiagnostic` trait

I did this mostly because it wasn't buying us much, and I'm
trying to simplify the public API of the types I'd like to
refactor in order to make the refactor simpler.

If we really want something like this, we can re-add it
later.

crates/red_knot_python_semantic/src/types/context.rs

@@ -59,11 +59,8 @@ impl<'db> InferContext<'db> {
         self.db
     }
 
-    pub(crate) fn extend<T>(&mut self, other: &T)
+    pub(crate) fn extend(&mut self, other: &TypeCheckDiagnostics) {
-    where
+        self.diagnostics.get_mut().extend(other);
-        T: WithDiagnostics,
-    {
-        self.diagnostics.get_mut().extend(other.diagnostics());
     }
 
     /// Reports a lint located at `ranged`.
@@ -223,7 +220,3 @@ pub(crate) enum InNoTypeCheck {
     /// The inference is known to be in an `@no_type_check` decorated function.
     Yes,
 }
-
-pub(crate) trait WithDiagnostics {
-    fn diagnostics(&self) -> &TypeCheckDiagnostics;
-}

crates/red_knot_python_semantic/src/types/infer.rs

@@ -88,7 +88,7 @@ use crate::util::subscript::{PyIndex, PySlice};
 use crate::Db;
 
 use super::class_base::ClassBase;
-use super::context::{InNoTypeCheck, InferContext, WithDiagnostics};
+use super::context::{InNoTypeCheck, InferContext};
 use super::diagnostic::{
     report_index_out_of_bounds, report_invalid_exception_caught, report_invalid_exception_cause,
     report_invalid_exception_raised, report_invalid_type_checking_constant,
@@ -439,12 +439,6 @@ impl<'db> TypeInference<'db> {
     }
 }
 
-impl WithDiagnostics for TypeInference<'_> {
-    fn diagnostics(&self) -> &TypeCheckDiagnostics {
-        &self.diagnostics
-    }
-}
-
 /// Whether the intersection type is on the left or right side of the comparison.
 #[derive(Debug, Clone, Copy)]
 enum IntersectionOn {
@@ -567,7 +561,7 @@ impl<'db> TypeInferenceBuilder<'db> {
             .extend(inference.declarations.iter());
         self.types.expressions.extend(inference.expressions.iter());
         self.types.deferred.extend(inference.deferred.iter());
-        self.context.extend(inference);
+        self.context.extend(inference.diagnostics());
     }
 
     fn file(&self) -> File {
@@ -1863,7 +1857,7 @@ impl<'db> TypeInferenceBuilder<'db> {
                     let unpacked = infer_unpack_types(self.db(), unpack);
                     let name_ast_id = name.scoped_expression_id(self.db(), self.scope());
                     if unpack_position == UnpackPosition::First {
-                        self.context.extend(unpacked);
+                        self.context.extend(unpacked.diagnostics());
                     }
                     unpacked.expression_type(name_ast_id)
                 }
@@ -2673,7 +2667,7 @@ impl<'db> TypeInferenceBuilder<'db> {
                 // Only copy the diagnostics if this is the first assignment to avoid duplicating the
                 // unpack assignments.
                 if unpack_position == UnpackPosition::First {
-                    self.context.extend(unpacked);
+                    self.context.extend(unpacked.diagnostics());
                 }
 
                 let name_ast_id = name.scoped_expression_id(self.db(), self.scope());
@@ -2973,7 +2967,7 @@ impl<'db> TypeInferenceBuilder<'db> {
                 TargetKind::Sequence(unpack_position, unpack) => {
                     let unpacked = infer_unpack_types(self.db(), unpack);
                     if unpack_position == UnpackPosition::First {
-                        self.context.extend(unpacked);
+                        self.context.extend(unpacked.diagnostics());
                     }
                     let name_ast_id = name.scoped_expression_id(self.db(), self.scope());
                     unpacked.expression_type(name_ast_id)

crates/red_knot_python_semantic/src/types/unpacker.rs

@@ -11,7 +11,7 @@ use crate::types::{infer_expression_types, todo_type, Type, TypeCheckDiagnostics
 use crate::unpack::{UnpackKind, UnpackValue};
 use crate::Db;
 
-use super::context::{InferContext, WithDiagnostics};
+use super::context::InferContext;
 use super::diagnostic::INVALID_ASSIGNMENT;
 use super::{TupleType, UnionType};
 
@@ -283,10 +283,9 @@ impl<'db> UnpackResult<'db> {
     pub(crate) fn expression_type(&self, expr_id: ScopedExpressionId) -> Type<'db> {
         self.targets[&expr_id]
     }
-}
 
-impl WithDiagnostics for UnpackResult<'_> {
+    /// Returns the diagnostics in this unpacking assignment.
-    fn diagnostics(&self) -> &TypeCheckDiagnostics {
+    pub(crate) fn diagnostics(&self) -> &TypeCheckDiagnostics {
         &self.diagnostics
     }
 }