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, 83 insertions, 0 deletions

diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index 7af70f0..3cb29c0 100644
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -3707,6 +3707,17 @@ shadow_tag_warned (const struct c_declspecs *declspecs, int warned)
 	      warned = 1;
 	      pending_xref_error ();
 	    }
+	  else if (declspecs->typespec_kind != ctsk_tagdef
+                   && declspecs->typespec_kind != ctsk_tagfirstref
+		   && declspecs->alignas_p)
+	    {
+	      if (warned != 1)
+		pedwarn (input_location, 0,
+			 "empty declaration with %<_Alignas%> "
+			  "does not redeclare tag");
+	      warned = 1;
+	      pending_xref_error ();
+	    }
 	  else
 	    {
 	      pending_invalid_xref = 0;
@@ -3782,6 +3793,12 @@ shadow_tag_warned (const struct c_declspecs *declspecs, int warned)
       warned = 2;
     }
 
+  if (!warned && !in_system_header && declspecs->alignas_p)
+    {
+      warning (0, "useless %<_Alignas%> in empty declaration");
+      warned = 2;
+    }
+
   if (warned != 1)
     {
       if (!found_tag)
@@ -4894,6 +4911,7 @@ grokdeclarator (const struct c_declarator *declarator,
   tree expr_dummy;
   bool expr_const_operands_dummy;
   enum c_declarator_kind first_non_attr_kind;
+  unsigned int alignas_align = 0;
 
   if (TREE_CODE (type) == ERROR_MARK)
     return error_mark_node;
@@ -5737,6 +5755,46 @@ grokdeclarator (const struct c_declarator *declarator,
   if (bitfield)
     check_bitfield_type_and_width (&type, width, name);
 
+  /* Reject invalid uses of _Alignas.  */
+  if (declspecs->alignas_p)
+    {
+      if (storage_class == csc_typedef)
+	error_at (loc, "alignment specified for typedef %qE", name);
+      else if (storage_class == csc_register)
+	error_at (loc, "alignment specified for %<register%> object %qE",
+		  name);
+      else if (decl_context == PARM)
+	{
+	  if (name)
+	    error_at (loc, "alignment specified for parameter %qE", name);
+	  else
+	    error_at (loc, "alignment specified for unnamed parameter");
+	}
+      else if (bitfield)
+	{
+	  if (name)
+	    error_at (loc, "alignment specified for bit-field %qE", name);
+	  else
+	    error_at (loc, "alignment specified for unnamed bit-field");
+	}
+      else if (TREE_CODE (type) == FUNCTION_TYPE)
+	error_at (loc, "alignment specified for function %qE", name);
+      else if (declspecs->align_log != -1)
+	{
+	  alignas_align = 1U << declspecs->align_log;
+	  if (alignas_align < TYPE_ALIGN_UNIT (type))
+	    {
+	      if (name)
+		error_at (loc, "%<_Alignas%> specifiers cannot reduce "
+			  "alignment of %qE", name);
+	      else
+		error_at (loc, "%<_Alignas%> specifiers cannot reduce "
+			  "alignment of unnamed field");
+	      alignas_align = 0;
+	    }
+	}
+    }
+
   /* Did array size calculations overflow?  */
 
   if (TREE_CODE (type) == ARRAY_TYPE
@@ -6117,6 +6175,13 @@ grokdeclarator (const struct c_declarator *declarator,
     /* Record constancy and volatility.  */
     c_apply_type_quals_to_decl (type_quals, decl);
 
+    /* Apply _Alignas specifiers.  */
+    if (alignas_align)
+      {
+	DECL_ALIGN (decl) = alignas_align * BITS_PER_UNIT;
+	DECL_USER_ALIGN (decl) = 1;
+      }
+
     /* If a type has volatile components, it should be stored in memory.
        Otherwise, the fact that those components are volatile
        will be ignored, and would even crash the compiler.
@@ -8709,6 +8774,7 @@ build_null_declspecs (void)
   ret->expr = 0;
   ret->decl_attr = 0;
   ret->attrs = 0;
+  ret->align_log = -1;
   ret->typespec_word = cts_none;
   ret->storage_class = csc_none;
   ret->expr_const_operands = true;
@@ -8732,6 +8798,7 @@ build_null_declspecs (void)
   ret->volatile_p = false;
   ret->restrict_p = false;
   ret->saturating_p = false;
+  ret->alignas_p = false;
   ret->address_space = ADDR_SPACE_GENERIC;
   return ret;
 }
@@ -9522,6 +9589,22 @@ declspecs_add_attrs (struct c_declspecs *specs, tree attrs)
   return specs;
 }
 
+/* Add an _Alignas specifier (expression ALIGN, or type whose
+   alignment is ALIGN) to the declaration specifiers SPECS, returning
+   SPECS.  */
+struct c_declspecs *
+declspecs_add_alignas (struct c_declspecs *specs, tree align)
+{
+  int align_log;
+  specs->alignas_p = true;
+  if (align == error_mark_node)
+    return specs;
+  align_log = check_user_alignment (align, true);
+  if (align_log > specs->align_log)
+    specs->align_log = align_log;
+  return specs;
+}
+
 /* Combine "long", "short", "signed", "unsigned" and "_Complex" type
    specifiers with any other type specifier to determine the resulting
    type.  This is where ISO C checks on complex types are made, since