util/attributes: handle #[export_name] on static items

This patch enables validation for the #[export_name] attribute when used
on static items. It reuses the validation logic introduced for functions
to ensure that statics also receive compile-time checks for malformed
inputs (e.g. non-string literals).

Fixes #4388

gcc/rust/ChangeLog:

	* util/rust-attributes.cc (AttributeChecker::visit): Add check for
	export_name on static items.

gcc/testsuite/ChangeLog:

	* rust/compile/issue-4388.rs: New test.

Signed-off-by: Jayant Chauhan <[email protected]>

Author: Pasta-coder

gcc/rust/util/rust-attributes.cc

@@ -1016,9 +1016,16 @@ AttributeChecker::visit (AST::StaticItem &item)
   BuiltinAttrDefinition result;
   for (auto &attribute : item.get_outer_attrs ())
     {
-      if (is_builtin (attribute, result) && result.name == Attrs::LINK_SECTION)
+      if (is_builtin (attribute, result))
 	{
-	  check_link_section_attribute (attribute);
+	  if (result.name == Attrs::LINK_SECTION)
+	    {
+	      check_link_section_attribute (attribute);
+	    }
+	  else if (result.name == Attrs::EXPORT_NAME)
+	    {
+	      check_export_name_attribute (attribute);
+	    }
 	}
     }
 }

gcc/testsuite/rust/compile/issue-4388.rs

@@ -0,0 +1,13 @@
+#[export_name] // { dg-error "malformed" }
+static A: i32 = 0;
+
+#[export_name(123)] // { dg-error "attribute must be a string literal" }
+static B: i32 = 0;
+
+#[export_name = 123] // { dg-error "attribute must be a string literal" }
+static C: i32 = 0;
+
+#[export_name = "valid_static"]
+static D: i32 = 0;
+
+fn main() {}