[E0769] Use of struct or tuple variant in struct or struct variant

gcc/rust/typecheck/rust-hir-type-check-pattern.cc

@@ -182,8 +182,14 @@ TypeCheckPattern::visit (HIR::StructPattern &pattern)
     {
       std::string variant_type
 	= TyTy::VariantDef::variant_type_string (variant->get_variant_type ());
-      rust_error_at (pattern.get_locus (),
-		     "expected struct variant, found %s variant %s",
+
+      rich_location rich_locus (line_table, pattern.get_locus ());
+      std::string rich_msg = "use the tuple variant pattern syntax instead "
+			     + variant->get_identifier () + "(_)";
+      rich_locus.add_fixit_replace (rich_msg.c_str ());
+
+      rust_error_at (rich_locus, ErrorCode::E0769,
+		     "%s variant %qs written as struct variant",
 		     variant_type.c_str (),
 		     variant->get_identifier ().c_str ());
       return;

gcc/testsuite/rust/compile/match4.rs

@@ -10,7 +10,7 @@ fn inspect(f: Foo) {
         Foo::A => {}
         Foo::B => {}
         Foo::C { a } => {}
-        // { dg-error "expected struct variant, found tuple variant C" "" { target *-*-* } .-1 }
+        // { dg-error "tuple variant .C. written as struct variant" "" { target *-*-* } .-1 }
         Foo::D { x, y } => {}
     }
 }