c-decl.c (grokdeclarator): Give zero-length arrays size zero.

        * c-decl.c (grokdeclarator): Give zero-length arrays size zero.
        Remove dead code.
        * c-typeck.c (push_init_level): Move checks for flexible array
        members and zero length arrays ...
        (pop_init_level): ... here.  Silently discard empty initializations.
        Remove dead code.
        * varasm.c (output_constructor): Update for sizeof change to
        zero-length arrays.

        * extend.texi (Zero Length): Clarify semantics.

        * gcc.dg/940510-1.c: Update expected error wording.
        * gcc.dg/array-2.c, gcc.dg/array-3.c, gcc.dg/array-4.c: New.

From-SVN: r38678

1 files changed, 9 insertions, 6 deletions

diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index 0521aa7..826608b 100644
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -4518,14 +4518,17 @@ grokdeclarator (declarator, declspecs, decl_context, initialized)
 	  if (type_quals)
 	    type = c_build_qualified_type (type, type_quals);
 
-#if 0
-	  /* Don't clear these; leave them set so that the array type
-	     or the variable is itself const or volatile.  */
-	  type_quals = TYPE_UNQUALIFIED;
-#endif
-
 	  if (size_varies)
 	    C_TYPE_VARIABLE_SIZE (type) = 1;
+
+	  /* The GCC extension for zero-length arrays differs from
+	     ISO flexible array members in that sizeof yields zero.  */
+	  if (size && integer_zerop (size))
+	    {
+	      layout_type (type);
+	      TYPE_SIZE (type) = bitsize_zero_node;
+	      TYPE_SIZE_UNIT (type) = size_zero_node;
+	    }
 	}
       else if (TREE_CODE (declarator) == CALL_EXPR)
 	{