From: Jason Merrill <jason@redhat.com>
Date: Mon, 1 Aug 2016 15:01:03 +0000 (-0400)
Subject: PR c++/72766 - ICE with VLA
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=1108a48582edec95d824d8eac8093be469aaf7b2;p=gcc.git

PR c++/72766 - ICE with VLA

	* constexpr.c (cxx_eval_pointer_plus_expression): Check constancy
	of nelts.
	* cp-gimplify.c (cp_fully_fold): Only maybe_constant_value in
	C++11 and up.

From-SVN: r238957
---

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 1037208d5bd..d792baf2475 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,11 @@
+2016-08-01  Jason Merrill  <jason@redhat.com>
+
+	PR c++/72766
+	* constexpr.c (cxx_eval_pointer_plus_expression): Check constancy
+	of nelts.
+	* cp-gimplify.c (cp_fully_fold): Only maybe_constant_value in
+	C++11 and up.
+
 2016-07-30 Martin Sebor  <msebor@redhat.com>
 
 	PR c++/60760
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 8bda97373b1..edade489401 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -3581,6 +3581,10 @@ cxx_eval_pointer_plus_expression (const constexpr_ctx *ctx, tree t,
       tree type = TREE_TYPE (op00);
       t = fold_convert_loc (loc, ssizetype, TREE_OPERAND (op00, 1));
       tree nelts = array_type_nelts_top (TREE_TYPE (TREE_OPERAND (op00, 0)));
+      nelts = cxx_eval_constant_expression (ctx, nelts, false, non_constant_p,
+					    overflow_p);
+      if (*non_constant_p)
+	return NULL_TREE;
       /* Don't fold an out-of-bound access.  */
       if (!tree_int_cst_le (t, nelts))
 	return NULL_TREE;
diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c
index 59953a6ee04..e28c9dfc799 100644
--- a/gcc/cp/cp-gimplify.c
+++ b/gcc/cp/cp-gimplify.c
@@ -1967,7 +1967,8 @@ cp_fully_fold (tree x)
     return x;
   /* FIXME cp_fold ought to be a superset of maybe_constant_value so we don't
      have to call both.  */
-  x = maybe_constant_value (x);
+  if (cxx_dialect >= cxx11)
+    x = maybe_constant_value (x);
   return cp_fold (x);
 }
 
diff --git a/gcc/testsuite/g++.dg/ext/vla16.C b/gcc/testsuite/g++.dg/ext/vla16.C
new file mode 100644
index 00000000000..c3e6ea1caba
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/vla16.C
@@ -0,0 +1,8 @@
+// PR c++/72766
+// { dg-options "-Wno-vla" }
+
+long fn1() {
+  const int a = fn1();
+  int b[a];
+  int c = *(&b[0] + sizeof(0));
+}