gccrs: add diagnostic for E0229 no associated type arguments allowed here

It seems bounds in qualified paths are not allowed to specify associated
type bindings because its going to be associated with the impl block
anyway.

Fixes Rust-GCC#2369

gcc/rust/ChangeLog:

	* typecheck/rust-hir-type-check-base.h: add flag
	* typecheck/rust-hir-type-check-type.cc (TypeCheckType::visit): likewise
	* typecheck/rust-tyty-bounds.cc: new diagnostic

gcc/testsuite/ChangeLog:

	* rust/compile/issue-2369.rs: New test.

Signed-off-by: Philip Herron <herron.philip@googlemail.com>

4 files changed, 43 insertions, 4 deletions

diff --git a/gcc/rust/typecheck/rust-hir-type-check-base.h b/gcc/rust/typecheck/rust-hir-type-check-base.h
index 8b07194..d500544 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-base.h
+++ b/gcc/rust/typecheck/rust-hir-type-check-base.h
@@ -40,7 +40,8 @@ protected:
   TyTy::TypeBoundPredicate get_predicate_from_bound (
     HIR::TypePath &path,
     tl::optional<std::reference_wrapper<HIR::Type>> associated_self,
-    BoundPolarity polarity = BoundPolarity::RegularBound);
+    BoundPolarity polarity = BoundPolarity::RegularBound,
+    bool is_qualified_type = false);
 
   bool check_for_unconstrained (
     const std::vector<TyTy::SubstitutionParamMapping> &params_to_constrain,
diff --git a/gcc/rust/typecheck/rust-hir-type-check-type.cc b/gcc/rust/typecheck/rust-hir-type-check-type.cc
index 15533c8..36bb4b0 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-type.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check-type.cc
@@ -193,8 +193,10 @@ TypeCheckType::visit (HIR::QualifiedPathInType &path)
     return;
 
   // get the predicate for the bound
-  auto specified_bound = get_predicate_from_bound (qual_path_type.get_trait (),
-						   qual_path_type.get_type ());
+  auto specified_bound
+    = get_predicate_from_bound (qual_path_type.get_trait (),
+				qual_path_type.get_type (),
+				BoundPolarity::RegularBound, true);
   if (specified_bound.is_error ())
     return;
 
diff --git a/gcc/rust/typecheck/rust-tyty-bounds.cc b/gcc/rust/typecheck/rust-tyty-bounds.cc
index 1d25d4a..e764ddc 100644
--- a/gcc/rust/typecheck/rust-tyty-bounds.cc
+++ b/gcc/rust/typecheck/rust-tyty-bounds.cc
@@ -196,7 +196,7 @@ TyTy::TypeBoundPredicate
 TypeCheckBase::get_predicate_from_bound (
   HIR::TypePath &type_path,
   tl::optional<std::reference_wrapper<HIR::Type>> associated_self,
-  BoundPolarity polarity)
+  BoundPolarity polarity, bool is_qualified_type_path)
 {
   TyTy::TypeBoundPredicate lookup = TyTy::TypeBoundPredicate::error ();
   bool already_resolved
@@ -222,6 +222,21 @@ TypeCheckBase::get_predicate_from_bound (
 	if (final_generic_seg.has_generic_args ())
 	  {
 	    args = final_generic_seg.get_generic_args ();
+	    if (args.get_binding_args ().size () > 0
+		&& associated_self.has_value () && is_qualified_type_path)
+	      {
+		auto &binding_args = args.get_binding_args ();
+
+		rich_location r (line_table, args.get_locus ());
+		for (auto it = binding_args.begin (); it != binding_args.end ();
+		     it++)
+		  {
+		    auto &arg = *it;
+		    r.add_fixit_remove (arg.get_locus ());
+		  }
+		rust_error_at (r, ErrorCode::E0229,
+			       "associated type bindings are not allowed here");
+	      }
 	  }
       }
       break;
diff --git a/gcc/testsuite/rust/compile/issue-2369.rs b/gcc/testsuite/rust/compile/issue-2369.rs
new file mode 100644
index 0000000..9475aef
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-2369.rs
@@ -0,0 +1,21 @@
+#[lang = "sized"]
+trait Sized {}
+
+fn main() {
+    pub trait Foo {
+        type A;
+        fn boo(&self) -> <Self as Foo>::A;
+    }
+
+    struct Bar;
+
+    impl Foo for isize {
+        type A = usize;
+        fn boo(&self) -> usize {
+            42
+        }
+    }
+
+    fn baz<I>(x: &<I as Foo<A = Bar>>::A) {}
+    // { dg-error "associated type bindings are not allowed here .E0229." "" { target *-*-* } .-1 }
+}