gccrs: Support fully qualified calls to trait items from CallExpr's

Fixes #2070

gcc/rust/ChangeLog:

	* backend/rust-compile-resolve-path.cc (HIRCompileBase::query_compile):
	reuse resolve_method_address to monomorphize the call if required
	* typecheck/rust-hir-type-check-path.cc (TypeCheckExpr::resolve_segments):
	allow matching against unimplemented trait item bounds

gcc/testsuite/ChangeLog:

	* rust/compile/issue-2070.rs: New test.

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

1 files changed, 16 insertions, 0 deletions

diff --git a/gcc/rust/backend/rust-compile-resolve-path.cc b/gcc/rust/backend/rust-compile-resolve-path.cc
index b7f1069..4814141 100644
--- a/gcc/rust/backend/rust-compile-resolve-path.cc
+++ b/gcc/rust/backend/rust-compile-resolve-path.cc
@@ -186,6 +186,7 @@ HIRCompileBase::query_compile (HirId ref, TyTy::BaseType *lookup,
     = ctx->get_mappings ()->lookup_hir_extern_item (ref, &parent_block);
   bool is_hir_item = resolved_item != nullptr;
   bool is_hir_extern_item = resolved_extern_item != nullptr;
+  bool is_fn = lookup->get_kind () == TyTy::TypeKind::FNDEF;
   if (is_hir_item)
     {
       if (!lookup->has_subsititions_defined ())
@@ -206,6 +207,21 @@ HIRCompileBase::query_compile (HirId ref, TyTy::BaseType *lookup,
     }
   else
     {
+      if (is_fn)
+	{
+	  TyTy::FnType *fn = static_cast<TyTy::FnType *> (lookup);
+	  TyTy::BaseType *receiver = nullptr;
+
+	  if (fn->is_method ())
+	    {
+	      receiver = fn->get_self_type ();
+	      receiver = receiver->destructure ();
+
+	      return resolve_method_address (fn, ref, receiver, final_segment,
+					     mappings, expr_locus);
+	    }
+	}
+
       HirId parent_impl_id = UNKNOWN_HIRID;
       HIR::ImplItem *resolved_item
 	= ctx->get_mappings ()->lookup_hir_implitem (ref, &parent_impl_id);