From: Jonathan Wakely <jwakely@redhat.com>
Date: Wed, 17 Apr 2019 13:13:30 +0000 (+0100)
Subject: Add constexpr to std::optional::value_or(U&&)&&
X-Git-Tag: basepoints/gcc-10~131
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=02c9b9ccffc66ec68ad4c2a0786c00984563d863;p=thirdparty%2Fgcc.git

Add constexpr to std::optional::value_or(U&&)&&

In C++1z drafts up to N4606 the constexpr keyword was missing from the
detailed description of this function, despite being shown in the class
synopsis.  That was fixed editorially for N4618, but our implementation
was not corrected to match.

	* include/std/optional (optional::value_or(U&&) &&): Add missing
	constexpr specifier.
	* testsuite/20_util/optional/constexpr/observers/4.cc: Check value_or
	for disengaged optionals and rvalue optionals.
	* testsuite/20_util/optional/observers/4.cc: Likewise.

From-SVN: r270409
---

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 55d2538b76e8..9ab8bb9154a5 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,11 @@
+2019-04-17  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/std/optional (optional::value_or(U&&) &&): Add missing
+	constexpr specifier.
+	* testsuite/20_util/optional/constexpr/observers/4.cc: Check value_or
+	for disengaged optionals and rvalue optionals.
+	* testsuite/20_util/optional/observers/4.cc: Likewise.
+
 2019-04-12  Thomas Rodgers  <trodgers@redhat.com>
 	
 	* include/pstl/algorithm_impl.h: Uglify identfiers.
diff --git a/libstdc++-v3/include/std/optional b/libstdc++-v3/include/std/optional
index d243930fed49..503d859bee6f 100644
--- a/libstdc++-v3/include/std/optional
+++ b/libstdc++-v3/include/std/optional
@@ -959,7 +959,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	}
 
       template<typename _Up>
-	_Tp
+	constexpr _Tp
 	value_or(_Up&& __u) &&
 	{
 	  static_assert(is_move_constructible_v<_Tp>);
diff --git a/libstdc++-v3/testsuite/20_util/optional/constexpr/observers/4.cc b/libstdc++-v3/testsuite/20_util/optional/constexpr/observers/4.cc
index 1f7f0e8b6a28..a085f53f8fab 100644
--- a/libstdc++-v3/testsuite/20_util/optional/constexpr/observers/4.cc
+++ b/libstdc++-v3/testsuite/20_util/optional/constexpr/observers/4.cc
@@ -25,10 +25,42 @@ struct value_type
   int i;
 };
 
-int main()
+void test01()
 {
   constexpr std::optional<value_type> o { value_type { 51 } };
   constexpr value_type fallback { 3 };
-  static_assert( o.value_or(fallback).i == 51, "" );
-  static_assert( o.value_or(fallback).i == (*o).i, "" );
+  static_assert( o.value_or(fallback).i == 51 );
+  static_assert( o.value_or(fallback).i == (*o).i );
+}
+
+void test02()
+{
+  constexpr std::optional<value_type> o;
+  constexpr value_type fallback { 3 };
+  static_assert( o.value_or(fallback).i == 3 );
+}
+
+template<typename T>
+  constexpr std::optional<value_type>
+  make_rvalue(T t)
+  { return std::optional<value_type>{t}; }
+
+void test03()
+{
+  constexpr value_type fallback { 3 };
+  static_assert( make_rvalue(value_type{51}).value_or(fallback).i == 51 );
+}
+
+void test04()
+{
+  constexpr value_type fallback { 3 };
+  static_assert( make_rvalue(std::nullopt).value_or(fallback).i == 3 );
+}
+
+int main()
+{
+  test01();
+  test02();
+  test03();
+  test04();
 }
diff --git a/libstdc++-v3/testsuite/20_util/optional/observers/4.cc b/libstdc++-v3/testsuite/20_util/optional/observers/4.cc
index c24e4e6856ec..5d608cdeaf73 100644
--- a/libstdc++-v3/testsuite/20_util/optional/observers/4.cc
+++ b/libstdc++-v3/testsuite/20_util/optional/observers/4.cc
@@ -26,10 +26,42 @@ struct value_type
   int i;
 };
 
-int main()
+void test01()
 {
   std::optional<value_type> o { value_type { 51 } };
   value_type fallback { 3 };
   VERIFY( o.value_or(fallback).i == 51 );
   VERIFY( o.value_or(fallback).i == (*o).i );
 }
+
+void test02()
+{
+  std::optional<value_type> o;
+  value_type fallback { 3 };
+  VERIFY( o.value_or(fallback).i == 3 );
+}
+
+void test03()
+{
+  std::optional<value_type> o { value_type { 51 } };
+  value_type fallback { 3 };
+  VERIFY( std::move(o).value_or(fallback).i == 51 );
+  VERIFY( o.has_value() );
+  VERIFY( std::move(o).value_or(fallback).i == (*o).i );
+}
+
+void test04()
+{
+  std::optional<value_type> o;
+  value_type fallback { 3 };
+  VERIFY( std::move(o).value_or(fallback).i == 3 );
+  VERIFY( !o.has_value() );
+}
+
+int main()
+{
+  test01();
+  test02();
+  test03();
+  test04();
+}