From: Jason Merrill <jason@redhat.com>
Date: Tue, 22 Dec 2020 21:40:37 +0000 (-0500)
Subject: c++: Fix constexpr array ICE [PR98332]
X-Git-Tag: releases/gcc-10.3.0~495
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f5cea9c5c4f8cce36963973e432a8575ef9ffd63;p=thirdparty%2Fgcc.git

c++: Fix constexpr array ICE [PR98332]

The element initializer was non-constant, so its CONSTRUCTOR element ended
up NULL, so unshare_constructor crashed trying to look at it.  This patch
fixes this in two places: First, by returning when we see a non-constant
initializer; second, by not crashing on NULL.

gcc/cp/ChangeLog:

	PR c++/98332
	* constexpr.c (unshare_constructor): Check for NULL.
	(cxx_eval_vec_init_1): Always exit early if non-constant.

gcc/testsuite/ChangeLog:

	PR c++/98332
	* g++.dg/cpp0x/constexpr-overflow3.C: New test.
---

diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index ff6518d2de68..1f22a8b9ef8a 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -1464,7 +1464,7 @@ unshare_constructor (tree t MEM_STAT_DECL)
       vec<constructor_elt, va_gc> *v = CONSTRUCTOR_ELTS (n);
       constructor_elt *ce;
       for (HOST_WIDE_INT i = 0; vec_safe_iterate (v, i, &ce); ++i)
-	if (TREE_CODE (ce->value) == CONSTRUCTOR)
+	if (ce->value && TREE_CODE (ce->value) == CONSTRUCTOR)
 	  ptrs.safe_push (&ce->value);
     }
   return t;
@@ -4139,7 +4139,7 @@ cxx_eval_vec_init_1 (const constexpr_ctx *ctx, tree atype, tree init,
 	  eltinit = cxx_eval_constant_expression (&new_ctx, eltinit, lval,
 						  non_constant_p, overflow_p);
 	}
-      if (*non_constant_p && !ctx->quiet)
+      if (*non_constant_p)
 	break;
       if (new_ctx.ctor != ctx->ctor)
 	{
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-overflow3.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-overflow3.C
new file mode 100644
index 000000000000..61766257e39f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-overflow3.C
@@ -0,0 +1,7 @@
+// PR c++/98332
+// { dg-do compile { target c++11 } }
+
+#include <limits.h>
+
+struct S { int a = INT_MAX + 1; }; // { dg-warning "overflow" }
+struct { S b[2][1][1][1]; } c;