c-decl.c (shadow_tag_warned, [...]): Handle _Alignas specifiers.

	* c-decl.c (shadow_tag_warned, grokdeclarator): Handle _Alignas
	specifiers.
	(build_null_declspecs): Initialize align_log and alignas_p fields.
	(declspecs_add_alignas): New.
	* c-parser.c (c_token_starts_declspecs): Handle RID_ALIGNAS.
	(c_parser_declspecs): Handle _Alignas specifiers.
	(c_parser_alignas_specifier): New.
	(c_parser_alignof_expression): Diagnose alignof use for non-C1X.
	Diagnose _Alignof (expression).
	* c-tree.h (struct c_declspecs): Add align_log and alignas_p
	fields.
	(declspecs_add_alignas): Declare.
	* ginclude/stddef.h (max_align_t): Define for C1X and C++11.
	* ginclude/stdalign.h: New.
	* Makefile.in (USER_H): Add stdalign.h.

c-family:
	* c-common.c (c_common_reswords): Add _Alignas and _Alignof.
	(c_sizeof_or_alignof_type): Diagnose alignof applied to a function
	type.
	(check_user_alignment): New.  Split out of
	handle_aligned_attribute.  Disallow integer constants with
	noninteger types.  Conditionally allow zero.
	(handle_aligned_attribute): Use check_user_alignment.
	* c-common.h (RID_ALIGNAS, check_user_alignment): New.

testsuite:
	* g++.dg/cpp0x/alignof3.C, gcc.dg/c1x-align-1.c,
	gcc.dg/c1x-align-2.c, gcc.dg/c1x-align-3.c, gcc.dg/c1x-align-4.c,
	gcc.dg/c90-align-1.c, gcc.dg/c99-align-1.c: New tests.
	* gcc.dg/gnu89-const-expr-1.c, gcc.dg/gnu90-const-expr-1.c,
	gcc.dg/gnu99-const-expr-1.c, gcc.dg/gnu99-static-1.c: Update
	expected diagnostics.

From-SVN: r181048

1 files changed, 67 insertions, 1 deletions

diff --git a/gcc/c-parser.c b/gcc/c-parser.c
index 8db203a..58bcb02 100644
--- a/gcc/c-parser.c
+++ b/gcc/c-parser.c
@@ -650,6 +650,7 @@ c_token_starts_declspecs (c_token *token)
 	case RID_FRACT:
 	case RID_ACCUM:
 	case RID_SAT:
+	case RID_ALIGNAS:
 	  return true;
 	default:
 	  return false;
@@ -1120,6 +1121,7 @@ static struct c_typespec c_parser_enum_specifier (c_parser *);
 static struct c_typespec c_parser_struct_or_union_specifier (c_parser *);
 static tree c_parser_struct_declaration (c_parser *);
 static struct c_typespec c_parser_typeof_specifier (c_parser *);
+static tree c_parser_alignas_specifier (c_parser *);
 static struct c_declarator *c_parser_declarator (c_parser *, bool, c_dtr_syn,
 						 bool *);
 static struct c_declarator *c_parser_direct_declarator (c_parser *, bool,
@@ -1890,9 +1892,11 @@ c_parser_static_assert_declaration_no_semi (c_parser *parser)
      type-specifier declaration-specifiers[opt]
      type-qualifier declaration-specifiers[opt]
      function-specifier declaration-specifiers[opt]
+     alignment-specifier declaration-specifiers[opt]
 
    Function specifiers (inline) are from C99, and are currently
-   handled as storage class specifiers, as is __thread.
+   handled as storage class specifiers, as is __thread.  Alignment
+   specifiers are from C1X.
 
    C90 6.5.1, C99 6.7.1:
    storage-class-specifier:
@@ -1991,6 +1995,7 @@ c_parser_declspecs (c_parser *parser, struct c_declspecs *specs,
     {
       struct c_typespec t;
       tree attrs;
+      tree align;
       location_t loc = c_parser_peek_token (parser)->location;
 
       /* If we cannot accept a type, exit if the next token must start
@@ -2169,6 +2174,10 @@ c_parser_declspecs (c_parser *parser, struct c_declspecs *specs,
 	  attrs = c_parser_attributes (parser);
 	  declspecs_add_attrs (specs, attrs);
 	  break;
+	case RID_ALIGNAS:
+	  align = c_parser_alignas_specifier (parser);
+	  declspecs_add_alignas (specs, align);
+	  break;
 	default:
 	  goto out;
 	}
@@ -2751,6 +2760,45 @@ c_parser_typeof_specifier (c_parser *parser)
   return ret;
 }
 
+/* Parse an alignment-specifier.
+
+   C1X 6.7.5:
+
+   alignment-specifier:
+     _Alignas ( type-name )
+     _Alignas ( constant-expression )
+*/
+
+static tree
+c_parser_alignas_specifier (c_parser * parser)
+{
+  tree ret = error_mark_node;
+  location_t loc = c_parser_peek_token (parser)->location;
+  gcc_assert (c_parser_next_token_is_keyword (parser, RID_ALIGNAS));
+  c_parser_consume_token (parser);
+  if (!flag_isoc1x)
+    {
+      if (flag_isoc99)
+	pedwarn (loc, OPT_pedantic,
+		 "ISO C99 does not support %<_Alignas%>");
+      else
+	pedwarn (loc, OPT_pedantic,
+		 "ISO C90 does not support %<_Alignas%>");
+    }
+  if (!c_parser_require (parser, CPP_OPEN_PAREN, "expected %<(%>"))
+    return ret;
+  if (c_parser_next_tokens_start_typename (parser, cla_prefer_id))
+    {
+      struct c_type_name *type = c_parser_type_name (parser);
+      if (type != NULL)
+	ret = c_alignof (loc, groktypename (type, NULL, NULL));
+    }
+  else
+    ret = c_parser_expr_no_commas (parser, NULL).value;
+  c_parser_skip_until_found (parser, CPP_CLOSE_PAREN, "expected %<)%>");
+  return ret;
+}
+
 /* Parse a declarator, possibly an abstract declarator (C90 6.5.4,
    6.5.5, C99 6.7.5, 6.7.6).  If TYPE_SEEN_P then a typedef name may
    be redeclared; otherwise it may not.  KIND indicates which kind of
@@ -5759,6 +5807,8 @@ c_parser_cast_expression (c_parser *parser, struct c_expr *after)
      __alignof__ ( type-name )
      && identifier
 
+   (C1X permits _Alignof with type names only.)
+
    unary-operator: one of
      __extension__ __real__ __imag__
 
@@ -5942,7 +5992,21 @@ c_parser_alignof_expression (c_parser *parser)
 {
   struct c_expr expr;
   location_t loc = c_parser_peek_token (parser)->location;
+  tree alignof_spelling = c_parser_peek_token (parser)->value;
   gcc_assert (c_parser_next_token_is_keyword (parser, RID_ALIGNOF));
+  /* A diagnostic is not required for the use of this identifier in
+     the implementation namespace; only diagnose it for the C1X
+     spelling because of existing code using the other spellings.  */
+  if (!flag_isoc1x
+      && strcmp (IDENTIFIER_POINTER (alignof_spelling), "_Alignof") == 0)
+    {
+      if (flag_isoc99)
+	pedwarn (loc, OPT_pedantic, "ISO C99 does not support %qE",
+		 alignof_spelling);
+      else
+	pedwarn (loc, OPT_pedantic, "ISO C90 does not support %qE",
+		 alignof_spelling);
+    }
   c_parser_consume_token (parser);
   c_inhibit_evaluation_warnings++;
   in_alignof++;
@@ -5991,6 +6055,8 @@ c_parser_alignof_expression (c_parser *parser)
       mark_exp_read (expr.value);
       c_inhibit_evaluation_warnings--;
       in_alignof--;
+      pedwarn (loc, OPT_pedantic, "ISO C does not allow %<%E (expression)%>",
+	       alignof_spelling);
       ret.value = c_alignof_expr (loc, expr.value);
       ret.original_code = ERROR_MARK;
       ret.original_type = NULL;