Add doc attribute checking on traits

Doc attribute checking was not performed on traits.

gcc/rust/ChangeLog:

	* util/rust-attributes.cc (check_doc_attribute): Change message.
	(AttributeChecker::visit): Add doc attribute checking on traits.

gcc/testsuite/ChangeLog:

	* rust/compile/attr_malformed_doc.rs: New test.

Signed-off-by: Pierre-Emmanuel Patry <[email protected]>

Author: P-E-P

gcc/rust/util/rust-attributes.cc

@@ -240,8 +240,8 @@ check_doc_attribute (const AST::Attribute &attribute)
     {
       rust_error_at (
 	attribute.get_locus (),
-	// FIXME: Improve error message here. Rustc has a very good one
-	"%<#[doc]%> cannot be an empty attribute");
+	"valid forms for the attribute are "
+	"%<#[doc(hidden|inline|...)]%> and %<#[doc = \" string \"]%>");
       return;
     }
 
@@ -826,6 +826,7 @@ void
 AttributeChecker::visit (AST::Trait &trait)
 {
   check_proc_macro_non_function (trait.get_outer_attrs ());
+  check_attributes (trait.get_outer_attrs ());
 }
 
 void

gcc/testsuite/rust/compile/attr_malformed_doc.rs

@@ -0,0 +1,3 @@
+// { dg-error "valid forms for the attribute are ...doc.hidden.inline....... and ...doc = . string ..." "" { target *-*-* } .+1 }
+#[doc]
+trait MyTrait {}