re PR c/21213 (segfault declaring a transparent union)

	PR c/21213
	* c-decl.c (finish_struct): Don't dereference NULL TYPE_FIELDS of
	transparent union.

testsuite:
	* gcc.dg/transparent-union-3.c: New test.

From-SVN: r98808

gcc/ChangeLog

 2005-04-27  Joseph S. Myers  <joseph@codesourcery.com>
 
+	PR c/21213
+	* c-decl.c (finish_struct): Don't dereference NULL TYPE_FIELDS of
+	transparent union.
+
+2005-04-27  Joseph S. Myers  <joseph@codesourcery.com>
+
 	PR c/20740
 	* c-format.c (init_dynamic_asm_fprintf_info): Give errors, not
 	assertion failures, if __gcc_host_wide_int__ is not properly

gcc/c-decl.c

@@ -5329,7 +5329,7 @@ finish_struct (tree t, tree fieldlist, tree attributes)
      make it one, warn and turn off the flag.  */
   if (TREE_CODE (t) == UNION_TYPE
       && TYPE_TRANSPARENT_UNION (t)
-      && TYPE_MODE (t) != DECL_MODE (TYPE_FIELDS (t)))
+      && (!TYPE_FIELDS (t) || TYPE_MODE (t) != DECL_MODE (TYPE_FIELDS (t))))
     {
       TYPE_TRANSPARENT_UNION (t) = 0;
       warning (0, "union cannot be made transparent");

gcc/testsuite/ChangeLog

 2005-04-27  Joseph S. Myers  <joseph@codesourcery.com>
 
+	PR c/21213
+	* gcc.dg/transparent-union-3.c: New test.
+
+2005-04-27  Joseph S. Myers  <joseph@codesourcery.com>
+
 	PR c/20740
 	* gcc.dg/format/asm_fprintf-2.c, gcc.dg/format/asm_fprintf-3.c,
 	gcc.dg/format/asm_fprintf-4.c, gcc.dg/format/asm_fprintf-5.c,

gcc/testsuite/gcc.dg/transparent-union-3.c

+/* Test for ICEs on invalid transparent unions (empty or no named
+   members).  Bug 21213.  */
+/* Origin: Joseph Myers <joseph@codesourcery.com> */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+enum e { A };
+
+union __attribute__((__transparent_union__)) ue1 { enum e; }; /* { dg-warning "warning: declaration does not declare anything" } */
+/* { dg-warning "warning: union cannot be made transparent" "" { target *-*-* } 9 } */
+union ue2 { enum e; } __attribute__((__transparent_union__)); /* { dg-warning "warning: declaration does not declare anything" } */
+/* { dg-warning "warning: union cannot be made transparent" "" { target *-*-* } 11 } */
+
+union __attribute__((__transparent_union__)) ui1 { int; }; /* { dg-warning "warning: declaration does not declare anything" } */
+/* { dg-warning "warning: union cannot be made transparent" "" { target *-*-* } 14 } */
+union ui2 { int; } __attribute__((__transparent_union__)); /* { dg-warning "warning: declaration does not declare anything" } */
+/* { dg-warning "warning: union cannot be made transparent" "" { target *-*-* } 16 } */
+
+union __attribute__((__transparent_union__)) u1 { };
+/* { dg-warning "warning: union cannot be made transparent" "" { target *-*-* } 19 } */
+union u2 { } __attribute__((__transparent_union__));
+/* { dg-warning "warning: union cannot be made transparent" "" { target *-*-* } 21 } */