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 b6f3e6e7a3143b8ed71804b76957191039449d53..f7cc4132085c7017bf255c566ef68a63e57583c6 100644 (file)
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -1524,7 +1524,7 @@ 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;
@@ -4548,7 +4548,7 @@ 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 (file)
index 0000000..22d4c59
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-overflow3.C
@@ -0,0 +1,5 @@
+// PR c++/98332
+// { dg-do compile { target c++11 } }
+
+struct S { int a = 2147483647 + 1; }; // { dg-warning "overflow" }
+struct { S b[2][1][1][1]; } c;