From 0e45c664e3f08eac144e82918a38174873ec176d Mon Sep 17 00:00:00 2001
From: Marek Polacek <polacek@redhat.com>
Date: Tue, 8 May 2018 19:30:57 +0000
Subject: [PATCH] re PR c++/85695 (if constexpr misevaluates typedefed type
 value)

	PR c++/85695
	* semantics.c (finish_if_stmt_cond): See through typedefs.

	* g++.dg/cpp1z/constexpr-if22.C: New test.

From-SVN: r260049
---
 gcc/cp/ChangeLog                            |  5 +++++
 gcc/cp/semantics.c                          |  2 +-
 gcc/testsuite/ChangeLog                     |  5 +++++
 gcc/testsuite/g++.dg/cpp1z/constexpr-if22.C | 21 +++++++++++++++++++++
 4 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-if22.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 65991150ef0..d80c15d2168 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2018-05-08  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/85695
+	* semantics.c (finish_if_stmt_cond): See through typedefs.
+
 2018-05-07  Jason Merrill  <jason@redhat.com>
 
 	PR c++/85646 - lambda visibility.
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 2b2b51b2a7e..195286ca751 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -736,7 +736,7 @@ finish_if_stmt_cond (tree cond, tree if_stmt)
       && !instantiation_dependent_expression_p (cond)
       /* Wait until instantiation time, since only then COND has been
 	 converted to bool.  */
-      && TREE_TYPE (cond) == boolean_type_node)
+      && TYPE_MAIN_VARIANT (TREE_TYPE (cond)) == boolean_type_node)
     {
       cond = instantiate_non_dependent_expr (cond);
       cond = cxx_constant_value (cond, NULL_TREE);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index dc19677d02c..3bfeb894b9b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-05-08  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/85695
+	* g++.dg/cpp1z/constexpr-if22.C: New test.
+
 2018-05-08  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/85693
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-if22.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-if22.C
new file mode 100644
index 00000000000..76f0c73476b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-if22.C
@@ -0,0 +1,21 @@
+// PR c++/85695
+// { dg-options -std=c++17 }
+
+template <typename T, T v>
+struct integral_constant {
+    using value_type = T;
+    static constexpr const value_type value = v;
+    constexpr operator value_type (void) const { return value; }
+};
+template <typename T> struct is_trivial
+    : public integral_constant<bool, __is_trivial(T)> {};
+
+template <typename T>
+T clone_object (const T& p)
+{
+    if constexpr (is_trivial<T>::value)
+        return p;
+    else
+        return p.clone();
+}
+int main (void) { return clone_object(0); }
-- 
2.30.2