fix: Fix type argument mismatch incorrectly triggering on inferred trait args

crates/hir-ty/src/infer/path.rs

@@ -207,7 +207,7 @@ impl InferenceContext<'_> {
                         (TypeNs::TraitId(trait_), true) => {
                             let self_ty = self.table.new_type_var();
                             let trait_ref =
-                                path_ctx.lower_trait_ref_from_resolved_path(trait_, self_ty);
+                                path_ctx.lower_trait_ref_from_resolved_path(trait_, self_ty, true);
                             drop_ctx(ctx, no_diagnostics);
                             self.resolve_trait_assoc_item(trait_ref, last_segment, id)
                         }

crates/hir-ty/src/lower.rs

@@ -538,7 +538,7 @@ impl<'a> TyLoweringContext<'a> {
             TypeNs::TraitId(tr) => tr,
             _ => return None,
         };
-        Some((ctx.lower_trait_ref_from_resolved_path(resolved, explicit_self_ty), ctx))
+        Some((ctx.lower_trait_ref_from_resolved_path(resolved, explicit_self_ty, false), ctx))
     }
 
     fn lower_trait_ref(

crates/hir-ty/src/lower/path.rs

@@ -166,6 +166,7 @@ impl<'a, 'b> PathLoweringContext<'a, 'b> {
                         let trait_ref = self.lower_trait_ref_from_resolved_path(
                             trait_,
                             TyKind::Error.intern(Interner),
+                            infer_args,
                         );
 
                         self.skip_resolved_segment();
@@ -830,8 +831,9 @@ impl<'a, 'b> PathLoweringContext<'a, 'b> {
         &mut self,
         resolved: TraitId,
         explicit_self_ty: Ty,
+        infer_args: bool,
     ) -> TraitRef {
-        let substs = self.trait_ref_substs_from_path(resolved, explicit_self_ty);
+        let substs = self.trait_ref_substs_from_path(resolved, explicit_self_ty, infer_args);
         TraitRef { trait_id: to_chalk_trait_id(resolved), substitution: substs }
     }
 
@@ -839,8 +841,9 @@ impl<'a, 'b> PathLoweringContext<'a, 'b> {
         &mut self,
         resolved: TraitId,
         explicit_self_ty: Ty,
+        infer_args: bool,
     ) -> Substitution {
-        self.substs_from_path_segment(resolved.into(), false, Some(explicit_self_ty), false)
+        self.substs_from_path_segment(resolved.into(), infer_args, Some(explicit_self_ty), false)
     }
 
     pub(super) fn assoc_type_bindings_from_type_bound<'c>(

crates/ide-diagnostics/src/handlers/incorrect_generics_len.rs

@@ -172,4 +172,16 @@ fn foo<T: Trait<Assoc<i32> = bool>>() {}
         "#,
         );
     }
+
+    #[test]
+    fn regression_19669() {
+        check_diagnostics(
+            r#"
+//- minicore: from
+fn main() {
+    let _: i32 = Into::into(0);
+}
+"#,
+        );
+    }
 }