re PR sanitizer/79589 (ICE in gimplify_compound_expr (gimplify.c:5712) with -fsanitize=undefined)

	PR sanitizer/79589
	* decl.c: Include gimplify.h.
	(cp_finish_decomp): Make sure there is no sharing of trees
	in between DECL_VALUE_EXPR of decomposition decls.

	* g++.dg/ubsan/pr79589.C: New test.

From-SVN: r245638

gcc/cp/ChangeLog

 2017-02-21  Jakub Jelinek  <jakub@redhat.com>
 
+	PR sanitizer/79589
+	* decl.c: Include gimplify.h.
+	(cp_finish_decomp): Make sure there is no sharing of trees
+	in between DECL_VALUE_EXPR of decomposition decls.
+
 	PR c++/79655
 	* constexpr.c (cxx_eval_array_reference): Diagnose negative subscript.
 

gcc/cp/decl.c

@@ -50,6 +50,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "plugin.h"
 #include "cilk.h"
 #include "builtins.h"
+#include "gimplify.h"
 
 /* Possible cases of bad specifiers type used by bad_specifiers. */
 enum bad_spec_place {
@@ -7470,7 +7471,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
 	{
 	  TREE_TYPE (v[i]) = eltype;
 	  layout_decl (v[i], 0);
-	  tree t = dexp;
+	  tree t = unshare_expr (dexp);
 	  t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
 			  eltype, t, size_int (i), NULL_TREE,
 			  NULL_TREE);
@@ -7489,7 +7490,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
 	{
 	  TREE_TYPE (v[i]) = eltype;
 	  layout_decl (v[i], 0);
-	  tree t = dexp;
+	  tree t = unshare_expr (dexp);
 	  t = build1_loc (DECL_SOURCE_LOCATION (v[i]),
 			  i ? IMAGPART_EXPR : REALPART_EXPR, eltype,
 			  t);
@@ -7507,7 +7508,7 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
 	{
 	  TREE_TYPE (v[i]) = eltype;
 	  layout_decl (v[i], 0);
-	  tree t = dexp;
+	  tree t = unshare_expr (dexp);
 	  convert_vector_to_array_for_subscript (DECL_SOURCE_LOCATION (v[i]),
 						 &t, size_int (i));
 	  t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
@@ -7606,7 +7607,8 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
 	  continue;
 	else
 	  {
-	    tree tt = finish_non_static_data_member (field, t, NULL_TREE);
+	    tree tt = finish_non_static_data_member (field, unshare_expr (t),
+						     NULL_TREE);
 	    if (REFERENCE_REF_P (tt))
 	      tt = TREE_OPERAND (tt, 0);
 	    TREE_TYPE (v[i]) = TREE_TYPE (tt);

gcc/testsuite/ChangeLog

+2017-02-21  Jakub Jelinek  <jakub@redhat.com>
+
+	PR sanitizer/79589
+	* g++.dg/ubsan/pr79589.C: New test.
+
 2017-02-21  Jeff Law  <law@redhat.com>
 
 	PR tree-optimization/79621

gcc/testsuite/g++.dg/ubsan/pr79589.C

+// PR sanitizer/79589
+// { dg-do compile }
+// { dg-options "-fsanitize=undefined -std=c++1z" }
+
+struct A { char a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r; } a[64];
+
+void
+foo ()
+{
+  int z = 0;
+  for (auto & [ b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s ] : a)
+    z += b + c + d + e + f + g + h + i + j + k + l + m + n + o + p + q + r + s;
+}