re PR middle-end/27945 (Packed struct of variable length has wrong size)

        PR middle-end/27945
        * stor-layout.c (layout_decl): Do pack variable size fields.

From-SVN: r128380

gcc/ChangeLog

+2007-09-11  Jason Merrill  <jason@redhat.com>
+
+	PR middle-end/27945
+	* stor-layout.c (layout_decl): Do pack variable size fields.	
+
 2007-09-11  Maxim Kuvyrkov  <maxim@codesourcery.com>
 
 	* config/m68k/predicates.md (movsi_const0_operand,

gcc/stor-layout.c

@@ -414,18 +414,11 @@ layout_decl (tree decl, unsigned int known_align)
       else
 	do_type_align (type, decl);
 
-      /* If the field is of variable size, we can't misalign it since we
-	 have no way to make a temporary to align the result.  But this
-	 isn't an issue if the decl is not addressable.  Likewise if it
-	 is of unknown size.
-
-	 Note that do_type_align may set DECL_USER_ALIGN, so we need to
-	 check old_user_align instead.  */
+      /* If the field is packed and not explicitly aligned, give it the
+	 minimum alignment.  Note that do_type_align may set
+	 DECL_USER_ALIGN, so we need to check old_user_align instead.  */
       if (packed_p
-	  && !old_user_align
-	  && (DECL_NONADDRESSABLE_P (decl)
-	      || DECL_SIZE_UNIT (decl) == 0
-	      || TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST))
+	  && !old_user_align)
 	DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
 
       if (! packed_p && ! DECL_USER_ALIGN (decl))

gcc/testsuite/gcc.dg/packed-vla.c

+/* { dg-do run } */
+/* { dg-options "" } */
+
+extern int printf (const char *, ...);
+extern void abort ();
+
+int func(int levels) 
+{
+  struct bar {
+    unsigned char	a;
+    int			b[levels];
+  } __attribute__ ((__packed__)) bar;
+
+  struct foo {
+    unsigned char	a;
+    int			b[4];
+  } __attribute__ ((__packed__)) foo;
+
+  printf("foo %d\n", sizeof(foo));
+  printf("bar %d\n", sizeof(bar));
+
+  if (sizeof (foo) != sizeof (bar))
+    abort ();
+}
+
+int main()
+{
+  func(4);
+  return 0;
+}