Fix error handling in assign_local_impl. (#8206)

Author: ilyalesokhin-starkware

crates/cairo-lang-semantic/src/expr/inference.rs

@@ -797,7 +797,7 @@ impl<'db> Inference<'db> {
                 let impl_ty = self
                     .db
                     .impl_type_concrete_implized(ImplTypeId::new(impl_id, trait_type_id, self.db))
-                    .map_err(|_| ErrorSet)?;
+                    .map_err(|diag_added| self.set_error(InferenceError::Reported(diag_added)))?;
                 if let Err(err_set) = self.conform_ty(ty, impl_ty) {
                     // Override the error with ImplTypeMismatch.
                     let ty0 = self.rewrite(ty).no_err();
@@ -809,24 +809,22 @@ impl<'db> Inference<'db> {
                 }
             }
             for (trait_constant, constant_id) in mappings.constants {
-                self.conform_const(
-                    constant_id,
-                    self.db
-                        .impl_constant_concrete_implized_value(ImplConstantId::new(
-                            impl_id,
-                            trait_constant,
-                            self.db,
-                        ))
-                        .map_err(|_| ErrorSet)?,
-                )?;
+                let concrete_impl_constant = self
+                    .db
+                    .impl_constant_concrete_implized_value(ImplConstantId::new(
+                        impl_id,
+                        trait_constant,
+                        self.db,
+                    ))
+                    .map_err(|diag_added| self.set_error(InferenceError::Reported(diag_added)))?;
+                self.conform_const(constant_id, concrete_impl_constant)?;
             }
             for (trait_impl, inner_impl_id) in mappings.impls {
-                self.conform_impl(
-                    inner_impl_id,
-                    self.db
-                        .impl_impl_concrete_implized(ImplImplId::new(impl_id, trait_impl, self.db))
-                        .map_err(|_| ErrorSet)?,
-                )?;
+                let concrete_impl_impl = self
+                    .db
+                    .impl_impl_concrete_implized(ImplImplId::new(impl_id, trait_impl, self.db))
+                    .map_err(|diag_added| self.set_error(InferenceError::Reported(diag_added)))?;
+                self.conform_impl(inner_impl_id, concrete_impl_impl)?;
             }
         }
         Ok(impl_id)

crates/cairo-lang-semantic/src/expr/test_data/inference

@@ -755,3 +755,35 @@ error: Type annotations needed. Failed to infer ?0.
  --> lib.cairo:1:13
 fn foo() -> Option {
             ^^^^^^
+
+//! > ==========================================================================
+
+//! > Use of an impl with and inferred and missing trait type.
+
+//! > test_runner_name
+test_function_diagnostics(expect_diagnostics: true)
+
+//! > function
+fn foo() {
+    MyTrait::f();
+}
+
+//! > function_name
+foo
+
+//! > module_code
+trait MyTrait {
+    type ty;
+    fn f() -> Self::ty;
+}
+impl MyImpl of MyTrait {
+    fn f() -> u32 {
+        5_u32
+    }
+}
+
+//! > expected_diagnostics
+error[E0004]: Not all trait items are implemented. Missing: 'ty'.
+ --> lib.cairo:5:6
+impl MyImpl of MyTrait {
+     ^^^^^^