re PR lto/78472 (warning: type of 's' does not match original declaration from…

re PR lto/78472 (warning: type of 's' does not match original declaration from zero length bitfield in C vs C++)

2016-11-23  Richard Biener  <rguenther@suse.de>

	PR lto/78472
	* tree.c (gimple_canonical_types_compatible_p): Ignore zero-sized
	fields.

	lto/
	* lto.c (hash_canonical_type): Ignore zero-sized fields.

	* g++.dg/lto/pr78472_0.c: New testcase.
	* g++.dg/lto/pr78472_1.C: Likewise.

From-SVN: r242746

gcc/ChangeLog

 2016-11-23  Richard Biener  <rguenther@suse.de>
+
+	PR lto/78472
+	* tree.c (gimple_canonical_types_compatible_p): Ignore zero-sized
+	fields.
+
+2016-11-23  Richard Biener  <rguenther@suse.de>
 	    Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.rog>
 
 	PR tree-optimization/78154

gcc/lto/ChangeLog

+2016-11-23  Richard Biener  <rguenther@suse.de>
+
+	PR lto/78472
+	* lto.c (hash_canonical_type): Ignore zero-sized fields.
+
 2016-11-21  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
 	PR c++/71973

gcc/lto/lto.c

@@ -373,7 +373,9 @@ hash_canonical_type (tree type)
       tree f;
 
       for (f = TYPE_FIELDS (type), nf = 0; f; f = TREE_CHAIN (f))
-	if (TREE_CODE (f) == FIELD_DECL)
+	if (TREE_CODE (f) == FIELD_DECL
+	    && (! DECL_SIZE (f)
+		|| ! integer_zerop (DECL_SIZE (f))))
 	  {
 	    iterative_hash_canonical_type (TREE_TYPE (f), hstate);
 	    nf++;

gcc/testsuite/ChangeLog

 2016-11-23  Richard Biener  <rguenther@suse.de>
+
+	PR lto/78472
+	* g++.dg/lto/pr78472_0.c: New testcase.
+	* g++.dg/lto/pr78472_1.C: Likewise.
+
+2016-11-23  Richard Biener  <rguenther@suse.de>
 	    Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.rog>
 
 	    PR tree-optimization/78154

gcc/testsuite/g++.dg/lto/pr78472_0.c

+// { dg-lto-do link }
+
+extern struct S
+{
+  unsigned i:4;
+  unsigned :0;
+} s;
+static void *f(void)
+{
+  return &s;
+}
+int main() {}

gcc/testsuite/g++.dg/lto/pr78472_1.C

+struct S
+{
+  unsigned i:4;
+  unsigned :0;
+} s;
+static void *f(void)
+{
+  return &s;
+}

gcc/tree.c

@@ -13708,10 +13708,14 @@ gimple_canonical_types_compatible_p (const_tree t1, const_tree t2,
 	     f1 || f2;
 	     f1 = TREE_CHAIN (f1), f2 = TREE_CHAIN (f2))
 	  {
-	    /* Skip non-fields.  */
-	    while (f1 && TREE_CODE (f1) != FIELD_DECL)
+	    /* Skip non-fields and zero-sized fields.  */
+	    while (f1 && (TREE_CODE (f1) != FIELD_DECL
+			  || (DECL_SIZE (f1)
+			      && integer_zerop (DECL_SIZE (f1)))))
 	      f1 = TREE_CHAIN (f1);
-	    while (f2 && TREE_CODE (f2) != FIELD_DECL)
+	    while (f2 && (TREE_CODE (f2) != FIELD_DECL
+			  || (DECL_SIZE (f2)
+			      && integer_zerop (DECL_SIZE (f2)))))
 	      f2 = TREE_CHAIN (f2);
 	    if (!f1 || !f2)
 	      break;