re PR c/22421 (problems with -Wformat and bit-fields)

	PR c/22421
	* c-decl.c (c_build_bitfield_integer_type): New function.
	(finish_struct): Call it.
	* c-pretty-print.c (pp_c_type_specifier): Handle bit-field types.

testsuite:
	* gcc.dg/format/bitfld-1.c: New test.

From-SVN: r102091

1 files changed, 25 insertions, 1 deletions

diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index 67c72a5..aff59bc1 100644
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -3774,6 +3774,30 @@ check_bitfield_type_and_width (tree *type, tree *width, const char *orig_name)
 	warning (0, "%qs is narrower than values of its type", name);
     }
 }
+
+/* Build a bit-field integer type for the given WIDTH and UNSIGNEDP.  */
+static tree
+c_build_bitfield_integer_type (unsigned HOST_WIDE_INT width, int unsignedp)
+{
+  /* Extended integer types of the same width as a standard type have
+     lesser rank, so those of the same width as int promote to int or
+     unsigned int and are valid for printf formats expecting int or
+     unsigned int.  To avoid such special cases, avoid creating
+     extended integer types for bit-fields if a standard integer type
+     is available.  */
+  if (width == TYPE_PRECISION (integer_type_node))
+    return unsignedp ? unsigned_type_node : integer_type_node;
+  if (width == TYPE_PRECISION (signed_char_type_node))
+    return unsignedp ? unsigned_char_type_node : signed_char_type_node;
+  if (width == TYPE_PRECISION (short_integer_type_node))
+    return unsignedp ? short_unsigned_type_node : short_integer_type_node;
+  if (width == TYPE_PRECISION (long_integer_type_node))
+    return unsignedp ? long_unsigned_type_node : long_integer_type_node;
+  if (width == TYPE_PRECISION (long_long_integer_type_node))
+    return (unsignedp ? long_long_unsigned_type_node
+	    : long_long_integer_type_node);
+  return build_nonstandard_integer_type (width, unsignedp);
+}
 
 /* Given declspecs and a declarator,
    determine the name and type of the object declared
@@ -5376,7 +5400,7 @@ finish_struct (tree t, tree fieldlist, tree attributes)
 	  if (width != TYPE_PRECISION (type))
 	    {
 	      TREE_TYPE (*fieldlistp)
-	        = build_nonstandard_integer_type (width, TYPE_UNSIGNED (type));
+		= c_build_bitfield_integer_type (width, TYPE_UNSIGNED (type));
 	      DECL_MODE (*fieldlistp) = TYPE_MODE (TREE_TYPE (*fieldlistp));
 	    }
 	  DECL_INITIAL (*fieldlistp) = 0;