Hi!
Apparently we can end up trying to store into a pointer-to-member
that has a PTRMEM_CST as its current value. Later code in
cxx_eval_store_expression is upset that it isn't a CONSTRUCTOR when
the type is actually aggregate.
The following patch fixes that, bootstrapped/regtested on x86_64-linux
and i686-linux, though I admit I'm not really sure if this is the best fix.
2017-02-21 Jakub Jelinek <ja...@redhat.com>
PR c++/79639
* constexpr.c (cxx_eval_store_expression): If *valp is a PTRMEM_CST,
call cplus_expand_constant on it first.
* g++.dg/cpp1y/constexpr-79639.C: New test.
--- gcc/cp/constexpr.c.jj 2017-02-21 13:49:06.000000000 +0100
+++ gcc/cp/constexpr.c 2017-02-21 14:57:30.290440638 +0100
@@ -3518,11 +3518,12 @@ cxx_eval_store_expression (const constex
wants to modify it. */
if (*valp == NULL_TREE)
{
- *valp = new_ctx.ctor = build_constructor (type, NULL);
- CONSTRUCTOR_NO_IMPLICIT_ZERO (new_ctx.ctor) = no_zero_init;
+ *valp = build_constructor (type, NULL);
+ CONSTRUCTOR_NO_IMPLICIT_ZERO (*valp) = no_zero_init;
}
- else
- new_ctx.ctor = *valp;
+ else if (TREE_CODE (*valp) == PTRMEM_CST)
+ *valp = cplus_expand_constant (*valp);
+ new_ctx.ctor = *valp;
new_ctx.object = target;
}
--- gcc/testsuite/g++.dg/cpp1y/constexpr-79639.C.jj 2017-02-21
15:06:42.625475572 +0100
+++ gcc/testsuite/g++.dg/cpp1y/constexpr-79639.C 2017-02-21
15:06:07.000000000 +0100
@@ -0,0 +1,27 @@
+// PR c++/79639
+// { dg-do compile { target c++14 } }
+
+struct A
+{
+ void foo () {}
+ void bar () {}
+};
+typedef void (A::*T) ();
+
+constexpr T
+foo (T f)
+{
+ f = 0;
+ return f;
+}
+
+constexpr T
+bar (T f)
+{
+ f = &A::bar;
+ return f;
+}
+
+constexpr T a = foo (&A::foo);
+constexpr T b = foo (&A::foo);
+static_assert (a == nullptr, "");
Jakub
