diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d7f73070448..7db96755ad3 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2010-01-01  Richard Guenther  <rguenther@suse.de>
+
+	PR c/42570
+	* c-decl.c (grokdeclarator): For zero-size arrays force
+	structural equality checks as layout_type does.
+
 2010-01-01  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* builtins.c: Update copyright to 2010.
diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index 0655197f5bc..a244a83e787 100644
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -1,6 +1,6 @@
 /* Process declarations and variables for C compiler.
    Copyright (C) 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
-   2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
+   2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -5394,6 +5394,7 @@ grokdeclarator (const struct c_declarator *declarator,
 		    gcc_assert (itype);
 		    TYPE_SIZE (type) = bitsize_zero_node;
 		    TYPE_SIZE_UNIT (type) = size_zero_node;
+		    SET_TYPE_STRUCTURAL_EQUALITY (type);
 		  }
 		if (array_parm_vla_unspec_p)
 		  {
@@ -5401,6 +5402,7 @@ grokdeclarator (const struct c_declarator *declarator,
 		    /* The type is complete.  C99 6.7.5.2p4  */
 		    TYPE_SIZE (type) = bitsize_zero_node;
 		    TYPE_SIZE_UNIT (type) = size_zero_node;
+		    SET_TYPE_STRUCTURAL_EQUALITY (type);
 		  }
 	      }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 46087948969..35ea64b52b3 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-01-01  Richard Guenther  <rguenther@suse.de>
+
+	PR c/42570
+	* gcc.c-torture/execute/pr42570.c: New testcase.
+
 2010-01-01  Richard Guenther  <rguenther@suse.de>
 
 	PR middle-end/42559
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr42570.c b/gcc/testsuite/gcc.c-torture/execute/pr42570.c
new file mode 100644
index 00000000000..99a8d807286
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr42570.c
@@ -0,0 +1,9 @@
+typedef unsigned char uint8_t;
+uint8_t foo[1][0];
+extern void abort (void);
+int main()
+{
+  if (sizeof (foo) != 0)
+    abort ();
+  return 0;
+}