From b51da998eee6b17630d7c9b1035cf47b77aa2af3 Mon Sep 17 00:00:00 2001
From: Ville Voutilainen <ville.voutilainen@gmail.com>
Date: Thu, 13 Sep 2018 00:10:43 +0300
Subject: [PATCH] re PR c++/87093 (is_constructible (__is_constructible()
 instrinsic) explicitly instantiates conversion member function of source)

PR c++/87093

gcc/cp

PR c++/87093
* method.c (constructible_expr): We're in an unevaluated context
in all cases, not just for class targets.

testsuite/

PR c++/87093
* g++.dg/ext/is_constructible2.C: New.

From-SVN: r264253
---
 gcc/cp/ChangeLog                             |  6 ++++++
 gcc/cp/method.c                              |  2 +-
 gcc/testsuite/g++.dg/ext/is_constructible2.C | 12 ++++++++++++
 3 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/ext/is_constructible2.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 9201d67c0ab..ca8939d9a08 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2018-09-13  Ville Voutilainen  <ville.voutilainen@gmail.com>
+
+	PR c++/87093
+	* method.c (constructible_expr): We're in an unevaluated context
+	in all cases, not just for class targets.
+
 2018-09-12  David Malcolm  <dmalcolm@redhat.com>
 
 	PR c++/85110
diff --git a/gcc/cp/method.c b/gcc/cp/method.c
index 0b208a8d52a..d75dacb1373 100644
--- a/gcc/cp/method.c
+++ b/gcc/cp/method.c
@@ -1144,11 +1144,11 @@ static tree
 constructible_expr (tree to, tree from)
 {
   tree expr;
+  cp_unevaluated cp_uneval_guard;
   if (CLASS_TYPE_P (to))
     {
       tree ctype = to;
       vec<tree, va_gc> *args = NULL;
-      cp_unevaluated cp_uneval_guard;
       if (!TYPE_REF_P (to))
 	to = cp_build_reference_type (to, /*rval*/false);
       tree ob = build_stub_object (to);
diff --git a/gcc/testsuite/g++.dg/ext/is_constructible2.C b/gcc/testsuite/g++.dg/ext/is_constructible2.C
new file mode 100644
index 00000000000..8f25e7e27d2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/is_constructible2.C
@@ -0,0 +1,12 @@
+// { dg-do compile { target c++11 } }
+
+#include <type_traits>
+
+template <typename T> struct x {
+  operator bool() {
+    static_assert(!std::is_same<T, T>::value, "");
+    return false;
+  }
+};
+
+static constexpr auto a = __is_constructible(bool, x<int>);
-- 
2.30.2