As discussed in PR 79433, the recommended way to test for new features
such as std::optional has problems. The current version of SD-6 at
https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations
says to simply check __has_include(optional). This test will be true
even when using -std=c++98, but actually including the header gives an
error. This works OK for ahead-of-time autoconf-style checks, but not
for preprocessor-based checks directly in the source code.
The latest draft of SD-6 (to be published soon) changes the
recommendation to use __has_include, then include the header and also
check for a feature-test macro e.g.
#ifdef __has_include
# if __has_include(optional)
# include <optional>
# if __cpp_lib_optional >= 201606
# define HAVE_STD_OPTIONAL
# endif
# endif
#endif
For this to work we need to make including <optional> always valid
(even in C++{98,03,11,14} modes) instead of failing with #error. When
included pre-C++17 the header should be empty, and specifically not
define the __cpp_lib_optional macro.
This implements that change. The <shared_mutex> header is also
affected for C++14, as that defines std::shared_timed_mutex in C++14
mode, and adds std::shared_mutex in C++17 mode.
With this change nothing else includes c++17_warning.h so we can
remove it.
In a follow-up patch I plan to do the same for the <experimental/*>
headers. The TS documents already give a macro for every header, and
LibFundTS suggests testing both __has_include and a macro, see ΒΆ3 at
https://rawgit.com/cplusplus/fundamentals-ts/v2/fundamentals-ts.html#general.feature.test
I'm not touching any of the headers added for C++11 (<forward_list>
etc.) because I think any user code that is relying on __has_include
will be using a std::lib with full C++11 support anyway.
Does anybody object to this change? Is getting a #error still useful,
given the existence of __has_include and __cpp_lib macros?
commit 34cc5bcef2b37ab0a6795c49346acecea3776dac
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Wed Sep 6 21:20:04 2017 +0100
PR libstdc++/79433 no #error for including headers with wrong -std
PR libstdc++/79433
* doc/xml/manual/status_cxx2017.xml: Update feature-test macros.
* doc/html/*: Regenerate.
* include/Makefile.am: Remove <bits/c++17_warning.h>.
* include/Makefile.in: Regenerate.
* include/bits/c++17_warning.h: Remove.
* include/bits/string_view.tcc: Do not include
<bits/c++17_warning.h>
for pre-C++17 modes.
* include/std/any: Likewise.
(__cpp_lib_any): Define.
* include/std/mutex (__cpp_lib_scoped_lock): Adjust value as per new
SD-6 draft.
* include/std/numeric (__cpp_lib_gcd_lcm): Define as per new SD-6
draft.
* include/std/optional: Do not include <bits/c++17_warning.h>.
(__cpp_lib_optional): Define.
* include/std/shared_mutex: Do not include <bits/c++14_warning.h>.
* include/std/string_view: Do not include <bits/c++17_warning.h>.
(__cpp_lib_string_view): Define.
* include/std/variant: Do not include <bits/c++17_warning.h>.
(__cpp_lib_variant): Define.
* testsuite/20_util/optional/cons/value_neg.cc: Adjust dg-error line
numbers.
* testsuite/26_numerics/gcd/1.cc: Test for __cpp_lib_gcd_lcm.
* testsuite/26_numerics/gcd/gcd_neg.cc: Adjust dg-error line
numbers.
* testsuite/26_numerics/lcm/1.cc: Test for __cpp_lib_gcd_lcm.
* testsuite/26_numerics/lcm/lcm_neg.cc: Adjust dg-error line
numbers.
* testsuite/30_threads/scoped_lock/requirements/typedefs.cc: Adjust
expected value of __cpp_lib_scoped_lock.
diff --git a/libstdc++-v3/doc/xml/manual/status_cxx2017.xml
b/libstdc++-v3/doc/xml/manual/status_cxx2017.xml
index 85e193daffa..fd66ac503a8 100644
--- a/libstdc++-v3/doc/xml/manual/status_cxx2017.xml
+++ b/libstdc++-v3/doc/xml/manual/status_cxx2017.xml
@@ -98,7 +98,9 @@ Feature-testing recommendations for C++</link>.
</link>
</entry>
<entry align="center"> 7 </entry>
- <entry> <code>__has_include(<variant>)</code> </entry>
+ <entry> <code>__has_include(<variant>)</code>,
+ <code>__cpp_lib_variant >= 201603</code>
+ </entry>
</row>
<row>
@@ -109,7 +111,9 @@ Feature-testing recommendations for C++</link>.
</link>
</entry>
<entry align="center"> 7 </entry>
- <entry> <code>__has_include(<optional>)</code> </entry>
+ <entry> <code>__has_include(<optional>)</code>,
+ <code>__cpp_lib_optional >= 201603</code>
+ </entry>
</row>
<row>
@@ -120,7 +124,9 @@ Feature-testing recommendations for C++</link>.
</link>
</entry>
<entry align="center"> 7 </entry>
- <entry> <code>__has_include(<any>)</code> </entry>
+ <entry> <code>__has_include(<any>)</code>,
+ <code>__cpp_lib_any >= 201603</code>
+ </entry>
</row>
<row>
@@ -131,7 +137,9 @@ Feature-testing recommendations for C++</link>.
</link>
</entry>
<entry align="center"> 7 </entry>
- <entry> <code>__has_include(<string_view>)</code> </entry>
+ <entry> <code>__has_include(<string_view>)</code>,
+ <code>__cpp_lib_string_view >= 201603</code>
+ </entry>
</row>
<row>
@@ -143,7 +151,9 @@ Feature-testing recommendations for C++</link>.
</link>
</entry>
<entry align="center"> No </entry>
- <entry> <code>__has_include(<memory_resource>)</code> </entry>
+ <entry> <code>__has_include(<memory_resource>)</code>,
+ <code>__cpp_lib_memory_resource >= 201603</code>
+ </entry>
</row>
<row>
@@ -616,7 +626,9 @@ Feature-testing recommendations for C++</link>.
</entry>
<entry align="center"> No </entry>
<entry><code> __has_include(<execution>) </code>,
- <code> __cpp_lib_parallel_algorithm >= 201603 </code></entry>
+ <code> __cpp_lib_execution >= 201603 </code>,
+ <code> __cpp_lib_parallel_algorithm >= 201603 </code>
+ </entry>
</row>
<row>
@@ -638,9 +650,7 @@ Feature-testing recommendations for C++</link>.
</link>
</entry>
<entry align="center"> 7 </entry>
- <entry><code> __cpp_lib_gcd >= 201606 </code>,
- <code> __cpp_lib_lcm >= 201606 </code>
- </entry>
+ <entry><code> __cpp_lib_gcd_lcm >= 201606 </code></entry>
</row>
<row>
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index a6517365827..6395f1e6ae0 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -96,7 +96,6 @@ bits_headers = \
${bits_srcdir}/boost_concept_check.h \
${bits_srcdir}/c++0x_warning.h \
${bits_srcdir}/c++14_warning.h \
- ${bits_srcdir}/c++17_warning.h \
${bits_srcdir}/char_traits.h \
${bits_srcdir}/codecvt.h \
${bits_srcdir}/concept_check.h \
diff --git a/libstdc++-v3/include/bits/c++17_warning.h
b/libstdc++-v3/include/bits/c++17_warning.h
deleted file mode 100644
index 759fdc92250..00000000000
--- a/libstdc++-v3/include/bits/c++17_warning.h
+++ /dev/null
@@ -1,37 +0,0 @@
-// Copyright (C) 2016-2017 Free Software Foundation, Inc.
-//
-// This file is part of the GNU ISO C++ Library. This library is free
-// software; you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the
-// Free Software Foundation; either version 3, or (at your option)
-// any later version.
-
-// This library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU General Public License for more details.
-
-// Under Section 7 of GPL version 3, you are granted additional
-// permissions described in the GCC Runtime Library Exception, version
-// 3.1, as published by the Free Software Foundation.
-
-// You should have received a copy of the GNU General Public License and
-// a copy of the GCC Runtime Library Exception along with this program;
-// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
-// <http://www.gnu.org/licenses/>.
-
-/** @file bits/c++17_warning.h
- * This is an internal header file, included by other library headers.
- * Do not attempt to use it directly. @headername{iosfwd}
- */
-
-#ifndef _CXX17_WARNING_H
-#define _CXX17_WARNING_H 1
-
-#if __cplusplus <= 201402L
-#error This file requires compiler and library support \
-for the ISO C++ 2017 standard. This support must be enabled \
-with the -std=c++17 or -std=gnu++17 compiler options.
-#endif
-
-#endif
diff --git a/libstdc++-v3/include/bits/string_view.tcc
b/libstdc++-v3/include/bits/string_view.tcc
index f4bd50fd4a0..ddd5496f1b6 100644
--- a/libstdc++-v3/include/bits/string_view.tcc
+++ b/libstdc++-v3/include/bits/string_view.tcc
@@ -36,9 +36,7 @@
#pragma GCC system_header
-#if __cplusplus <= 201402L
-# include <bits/c++17_warning.h>
-#else
+#if __cplusplus >= 201703L
namespace std _GLIBCXX_VISIBILITY(default)
{
diff --git a/libstdc++-v3/include/std/any b/libstdc++-v3/include/std/any
index 1e84302f0c0..eef510535d7 100644
--- a/libstdc++-v3/include/std/any
+++ b/libstdc++-v3/include/std/any
@@ -31,9 +31,7 @@
#pragma GCC system_header
-#if __cplusplus <= 201402L
-# include <bits/c++17_warning.h>
-#else
+#if __cplusplus >= 201703L
#include <typeinfo>
#include <new>
@@ -68,6 +66,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif
}
+#define __cpp_lib_any 201603
+
/**
* @brief A type-safe container of any type.
*
diff --git a/libstdc++-v3/include/std/mutex b/libstdc++-v3/include/std/mutex
index fadb9f60481..8c692a88ffd 100644
--- a/libstdc++-v3/include/std/mutex
+++ b/libstdc++-v3/include/std/mutex
@@ -556,8 +556,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
}
-#if __cplusplus > 201402L
-#define __cpp_lib_scoped_lock 201707
+#if __cplusplus >= 201703L
+#define __cpp_lib_scoped_lock 201703
/** @brief A scoped lock type for multiple lockable objects.
*
* A scoped_lock controls mutex ownership within a scope, releasing
diff --git a/libstdc++-v3/include/std/numeric b/libstdc++-v3/include/std/numeric
index 17d629db81d..2b804199c7e 100644
--- a/libstdc++-v3/include/std/numeric
+++ b/libstdc++-v3/include/std/numeric
@@ -121,7 +121,11 @@ namespace __detail
#if __cplusplus > 201402L
+#define __cpp_lib_gcd_lcm 201606
+// These were used in drafts of SD-6:
#define __cpp_lib_gcd 201606
+#define __cpp_lib_lcm 201606
+
/// Greatest common divisor
template<typename _Mn, typename _Nn>
constexpr common_type_t<_Mn, _Nn>
@@ -134,7 +138,6 @@ namespace __detail
return __detail::__gcd(__m, __n);
}
-#define __cpp_lib_lcm 201606
/// Least common multiple
template<typename _Mn, typename _Nn>
constexpr common_type_t<_Mn, _Nn>
diff --git a/libstdc++-v3/include/std/optional
b/libstdc++-v3/include/std/optional
index c697c1682a6..2743ef963b4 100644
--- a/libstdc++-v3/include/std/optional
+++ b/libstdc++-v3/include/std/optional
@@ -29,9 +29,9 @@
#ifndef _GLIBCXX_OPTIONAL
#define _GLIBCXX_OPTIONAL 1
-#if __cplusplus <= 201402L
-# include <bits/c++17_warning.h>
-#else
+#pragma GCC system_header
+
+#if __cplusplus >= 201703L
#include <utility>
#include <type_traits>
@@ -51,6 +51,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* @{
*/
+#define __cpp_lib_optional 201603
+
template<typename _Tp>
class optional;
diff --git a/libstdc++-v3/include/std/shared_mutex
b/libstdc++-v3/include/std/shared_mutex
index ff116c0e30d..295fdc7118c 100644
--- a/libstdc++-v3/include/std/shared_mutex
+++ b/libstdc++-v3/include/std/shared_mutex
@@ -31,9 +31,7 @@
#pragma GCC system_header
-#if __cplusplus <= 201103L
-# include <bits/c++14_warning.h>
-#else
+#if __cplusplus >= 201402L
#include <bits/c++config.h>
#include <condition_variable>
@@ -51,7 +49,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#ifdef _GLIBCXX_USE_C99_STDINT_TR1
#ifdef _GLIBCXX_HAS_GTHREADS
-#if __cplusplus > 201402L
+#if __cplusplus >= 201703L
#define __cpp_lib_shared_mutex 201505
class shared_mutex;
#endif
diff --git a/libstdc++-v3/include/std/string_view
b/libstdc++-v3/include/std/string_view
index 88a7686618c..bdbbbb9fbec 100644
--- a/libstdc++-v3/include/std/string_view
+++ b/libstdc++-v3/include/std/string_view
@@ -35,9 +35,7 @@
#pragma GCC system_header
-#if __cplusplus <= 201402L
-# include <bits/c++17_warning.h>
-#else
+#if __cplusplus >= 201703L
#include <limits>
#include <iosfwd>
@@ -49,6 +47,8 @@ namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
+#define __cpp_lib_string_view 201603
+
/**
* @class basic_string_view <string_view>
* @brief A non-owning reference to a string.
diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant
index d0c22e35d0f..ee2571b7857 100644
--- a/libstdc++-v3/include/std/variant
+++ b/libstdc++-v3/include/std/variant
@@ -31,9 +31,7 @@
#pragma GCC system_header
-#if __cplusplus <= 201402L
-# include <bits/c++17_warning.h>
-#else
+#if __cplusplus >= 201703L
#include <type_traits>
#include <utility>
@@ -70,6 +68,8 @@ namespace __variant
} // namespace __variant
} // namespace __detail
+#define __cpp_lib_variant 201603
+
template<typename... _Types> class tuple;
template<typename... _Types> class variant;
template <typename> struct hash;
diff --git a/libstdc++-v3/testsuite/20_util/optional/cons/value_neg.cc
b/libstdc++-v3/testsuite/20_util/optional/cons/value_neg.cc
index 524e302fec1..98964eadbde 100644
--- a/libstdc++-v3/testsuite/20_util/optional/cons/value_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/optional/cons/value_neg.cc
@@ -37,8 +37,8 @@ int main()
std::optional<std::unique_ptr<int>> oup2 = new int; // { dg-error
"conversion" }
struct U { explicit U(std::in_place_t); };
std::optional<U> ou(std::in_place); // { dg-error "no matching" }
- // { dg-error "no type" "" { target { *-*-* } } 493 }
- // { dg-error "no type" "" { target { *-*-* } } 503 }
- // { dg-error "no type" "" { target { *-*-* } } 560 }
+ // { dg-error "no type" "" { target { *-*-* } } 495 }
+ // { dg-error "no type" "" { target { *-*-* } } 505 }
+ // { dg-error "no type" "" { target { *-*-* } } 562 }
}
}
diff --git a/libstdc++-v3/testsuite/26_numerics/gcd/1.cc
b/libstdc++-v3/testsuite/26_numerics/gcd/1.cc
index 17e97a7e0ae..0f0b7b85b4e 100644
--- a/libstdc++-v3/testsuite/26_numerics/gcd/1.cc
+++ b/libstdc++-v3/testsuite/26_numerics/gcd/1.cc
@@ -20,9 +20,9 @@
#include <numeric>
-#ifndef __cpp_lib_gcd
+#ifndef __cpp_lib_gcd_lcm
# error "Feature-test macro for gcd missing"
-#elif __cpp_lib_gcd != 201606
+#elif __cpp_lib_gcd_lcm != 201606
# error "Feature-test macro for gcd has wrong value"
#endif
diff --git a/libstdc++-v3/testsuite/26_numerics/gcd/gcd_neg.cc
b/libstdc++-v3/testsuite/26_numerics/gcd/gcd_neg.cc
index 8c3494d7041..d88f145d754 100644
--- a/libstdc++-v3/testsuite/26_numerics/gcd/gcd_neg.cc
+++ b/libstdc++-v3/testsuite/26_numerics/gcd/gcd_neg.cc
@@ -31,9 +31,9 @@ test01()
std::gcd(0.1, 0.1); // { dg-error "from here" }
}
-// { dg-error "integers" "" { target *-*-* } 130 }
-// { dg-error "integers" "" { target *-*-* } 131 }
-// { dg-error "not bools" "" { target *-*-* } 132 }
-// { dg-error "not bools" "" { target *-*-* } 133 }
+// { dg-error "integers" "" { target *-*-* } 134 }
+// { dg-error "integers" "" { target *-*-* } 135 }
+// { dg-error "not bools" "" { target *-*-* } 136 }
+// { dg-error "not bools" "" { target *-*-* } 137 }
// { dg-prune-output "deleted function" }
// { dg-prune-output "invalid operands" }
diff --git a/libstdc++-v3/testsuite/26_numerics/lcm/1.cc
b/libstdc++-v3/testsuite/26_numerics/lcm/1.cc
index 81cb91437ba..367f0a3e0e3 100644
--- a/libstdc++-v3/testsuite/26_numerics/lcm/1.cc
+++ b/libstdc++-v3/testsuite/26_numerics/lcm/1.cc
@@ -20,9 +20,9 @@
#include <numeric>
-#ifndef __cpp_lib_lcm
+#ifndef __cpp_lib_gcd_lcm
# error "Feature-test macro for lcm missing"
-#elif __cpp_lib_lcm != 201606
+#elif __cpp_lib_gcd_lcm != 201606
# error "Feature-test macro for lcm has wrong value"
#endif
diff --git a/libstdc++-v3/testsuite/26_numerics/lcm/lcm_neg.cc
b/libstdc++-v3/testsuite/26_numerics/lcm/lcm_neg.cc
index abcac4f18c1..7a908a4568f 100644
--- a/libstdc++-v3/testsuite/26_numerics/lcm/lcm_neg.cc
+++ b/libstdc++-v3/testsuite/26_numerics/lcm/lcm_neg.cc
@@ -31,9 +31,9 @@ test01()
std::lcm(0.1, 0.1); // { dg-error "from here" }
}
-// { dg-error "integers" "" { target *-*-* } 143 }
-// { dg-error "integers" "" { target *-*-* } 144 }
-// { dg-error "not bools" "" { target *-*-* } 145 }
-// { dg-error "not bools" "" { target *-*-* } 146 }
+// { dg-error "integers" "" { target *-*-* } 146 }
+// { dg-error "integers" "" { target *-*-* } 147 }
+// { dg-error "not bools" "" { target *-*-* } 148 }
+// { dg-error "not bools" "" { target *-*-* } 149 }
// { dg-prune-output "deleted function" }
// { dg-prune-output "invalid operands" }
diff --git
a/libstdc++-v3/testsuite/30_threads/scoped_lock/requirements/typedefs.cc
b/libstdc++-v3/testsuite/30_threads/scoped_lock/requirements/typedefs.cc
index 0a8903ebaab..b8a09042094 100644
--- a/libstdc++-v3/testsuite/30_threads/scoped_lock/requirements/typedefs.cc
+++ b/libstdc++-v3/testsuite/30_threads/scoped_lock/requirements/typedefs.cc
@@ -27,7 +27,7 @@
#ifndef __cpp_lib_scoped_lock
# error "Feature-test macro for scoped_lock missing"
-#elif __cpp_lib_scoped_lock != 201707
+#elif __cpp_lib_scoped_lock != 201703
# error "Feature-test macro for scoped_lock has wrong value"
#endif
