C++ PATCH for c++/91304 - prefix attributes ignored in condition

[Marek Polacek]

Currently, we disregard prefix attributes in conditions, e.g.:

  if ([[maybe_unused]] int i = f()) { }

The problem here is that although we've parsed the attribute, it
was never passed down to start_decl, so the effects were lost.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2019-08-21  Marek Polacek  <pola...@redhat.com>

        PR c++/91304 - prefix attributes ignored in condition.
        * parser.c (cp_parser_condition): Handle prefix attributes.

        * g++.dg/cpp0x/gen-attrs-70.C: New test.

diff --git gcc/cp/parser.c gcc/cp/parser.c
index dbbfe1dbc2f..b410a6c030f 100644
--- gcc/cp/parser.c
+++ gcc/cp/parser.c
@@ -12066,6 +12066,10 @@ cp_parser_condition (cp_parser* parser)
   /* Restore the saved message.  */
   parser->type_definition_forbidden_message = saved_message;
 
+  /* Gather the attributes that were provided with the
+     decl-specifiers.  */
+  tree prefix_attributes = type_specifiers.attributes;
+
   cp_parser_maybe_commit_to_declaration (parser,
                                         type_specifiers.any_specifiers_p);
 
@@ -12116,7 +12120,7 @@ cp_parser_condition (cp_parser* parser)
          /* Create the declaration.  */
          decl = start_decl (declarator, &type_specifiers,
                             /*initialized_p=*/true,
-                            attributes, /*prefix_attributes=*/NULL_TREE,
+                            attributes, prefix_attributes,
                             &pushed_scope);
 
          /* Parse the initializer.  */
diff --git gcc/testsuite/g++.dg/cpp0x/gen-attrs-70.C 
gcc/testsuite/g++.dg/cpp0x/gen-attrs-70.C
new file mode 100644
index 00000000000..90a2e97a3f6
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/gen-attrs-70.C
@@ -0,0 +1,13 @@
+// PR c++/91304 - prefix attributes ignored in condition.
+// { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wall -Wextra" }
+
+int f();
+
+void g()
+{   
+  if ([[maybe_unused]] int i = f()) { }
+  if ([[deprecated]] int i = f()) { i = 10; } // { dg-warning ".i. is 
deprecated" }
+  if (int i [[maybe_unused]] = f()) { }
+  if (int i [[deprecated]] = f()) { i = 10; } // { dg-warning ".i. is 
deprecated" }
+}