@@ -3324,8 +3324,16 @@ cxx_eval_array_reference (const constexpr_ctx *ctx, tree t,
}
/* If it's within the array bounds but doesn't have an explicit
- initializer, it's value-initialized. */
- tree val = build_value_init (elem_type, tf_warning_or_error);
+ initializer, it's initialized from {}. But use build_value_init
+ directly for non-aggregates to avoid creating a garbage CONSTRUCTOR. */
+ tree val;
+ if (CP_AGGREGATE_TYPE_P (elem_type))
+ {
+ tree empty_ctor = build_constructor (init_list_type_node, NULL);
+ val = digest_init (elem_type, empty_ctor, tf_warning_or_error);
+ }
+ else
+ val = build_value_init (elem_type, tf_warning_or_error);
return cxx_eval_constant_expression (ctx, val, lval, non_constant_p,
overflow_p);
}
new file mode 100644
@@ -0,0 +1,10 @@
+// PR c++/90951
+// { dg-do compile { target c++11 } }
+
+#define assert(expr) static_assert (expr, #expr)
+
+struct S { const char a[2]; };
+
+constexpr struct S a[1][1][1] = { };
+
+assert ('\0' == *a[0][0][0].a);
Value-initialization is importantly different from {}-initialization for this testcase, where the former calls the deleted S constructor and the latter initializes S happily. Tested x86_64-pc-linux-gnu, applying to trunk. PR c++/90951 * constexpr.c (cxx_eval_array_reference): {}-initialize missing elements instead of value-initializing them. --- gcc/cp/constexpr.c | 12 ++++++++++-- gcc/testsuite/g++.dg/cpp0x/constexpr-array24.C | 10 ++++++++++ 2 files changed, 20 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-array24.C base-commit: a1c9c9ff06ab15e697d5bac6ea6e5da2df840cf5