From 25139006e58a7ca7b708a742af8170f399d7db63 Mon Sep 17 00:00:00 2001
From: Paolo Carlini <paolo.carlini@oracle.com>
Date: Wed, 4 Oct 2017 20:58:52 +0000
Subject: [PATCH] =?utf8?q?re=20PR=20c++/78131=20(Inconsistent=20evaluation?=
 =?utf8?q?=20for=20`constexpr`=20lambdas=20in=20templates=20between=20`sta?=
 =?utf8?q?tic=5Fassert`,=20`if=20constexpr(=E2=80=A6)`=20and=20`constexpr`?=
 =?utf8?q?=20variables)?=
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2017-10-04  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/78131
	* g++.dg/cpp1z/constexpr-lambda17.C: New.

From-SVN: r253431
---
 gcc/testsuite/ChangeLog                         |  5 +++++
 gcc/testsuite/g++.dg/cpp1z/constexpr-lambda17.C | 30 +++++++++++++++++++++++++
 2 files changed, 35 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-lambda17.C

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 6e8680b3312..b1e3edcb828 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2017-10-04  Paolo Carlini  <paolo.carlini@oracle.com>
 
+	PR c++/78131
+	* g++.dg/cpp1z/constexpr-lambda17.C: New.
+
+2017-10-04  Paolo Carlini  <paolo.carlini@oracle.com>
+
 	PR c++/78018
 	* g++.dg/cpp1y/lambda-generic-78018.C: New.
 
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda17.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda17.C
new file mode 100644
index 00000000000..44bd2b83f94
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda17.C
@@ -0,0 +1,30 @@
+// PR c++/78131
+// { dg-options -std=c++17 }
+
+template <typename TF>
+constexpr auto f(TF)
+{
+    return [](auto...) constexpr { return true; };
+}   
+
+// Compiles and works as intended.
+template <typename T0>
+void ok_0(T0)
+{
+    static_assert(f([](auto x) -> decltype(x){})(T0{}));
+}
+
+// Compiles and works as intended.
+template <typename T0>
+void ok_1(T0)
+{
+    constexpr auto a = f([](auto x) -> decltype(x){})(T0{});
+    if constexpr(a) { }
+}
+
+// Compile-time error!
+template <typename T0>
+void fail_0(T0)
+{
+    if constexpr(f([](auto x) -> decltype(x){})(T0{})) { } 
+}
-- 
2.11.4.GIT