Re: [v3 PATCH] Implement LWG 2221, No formatted output operator for nullptr

[Jonathan Wakely <jwakely@redhat.com>]

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On 04/12/17 23:04 +0000, Jonathan Wakely wrote:
>On 03/12/17 23:08 +0200, Ville Voutilainen wrote:
>>Tested on Linux-x64.
>>
>>2017-11-14  Ville Voutilainen  <ville.voutilainen@gmail.com>
>>
>>   Implement LWG 2221
>>   * include/std/ostream (operator<<(nullptr_t)): New.
>>   * testsuite/27_io/basic_ostream/inserters_other/char/lwg2221.cc: New.
>
>>diff --git a/libstdc++-v3/include/std/ostream b/libstdc++-v3/include/std/ostream
>>index f7cab03..18011bc 100644
>>--- a/libstdc++-v3/include/std/ostream
>>+++ b/libstdc++-v3/include/std/ostream
>>@@ -245,6 +245,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>      operator<<(const void* __p)
>>      { return _M_insert(__p); }
>>
>>+#if __cplusplus > 201402L
>>+      __ostream_type&
>>+      operator<<(nullptr_t)
>>+      { return *this << "nullptr"; }
>>+#endif
>
>As discussed on IRC, this requires a new symbol to be exported for the
>std::ostream and std::wostream explicit instantiations, or the new
>test will fail to link at -O0.
>
>That should wait for stage 1.
>

This patch for a C++17 feature (posted over a year ago) should have
gone in during stage 1. I've taken care of the symbol exports that
were missing from the original patch.

Tested x86_64-linux, committed to trunk.


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commit 81a14252318562c32e5a0c466a39568e741ab6e6
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Jan 10 11:44:19 2019 +0000

    Implement LWG 2221: formatted output operator for nullptr
    
    2019-01-10  Ville Voutilainen  <ville.voutilainen@gmail.com>
                Jonathan Wakely  <jwakely@redhat.com>
    
            Implement LWG 2221
            * config/abi/pre/gnu.ver (GLIBCXX_3.4): Tighten patterns.
            (GLIBCXX_3.4.26): Add new exports.
            * include/Makefile.am: Add ostream-inst.cc. Move string-inst.cc to
            correct list of sources.
            * include/Makefile.in: Regenerate.
            * include/std/ostream (operator<<(nullptr_t)): New member function.
            * src/c++17/ostream-inst.cc: New file.
            * testsuite/27_io/basic_ostream/inserters_other/char/lwg2221.cc: New
            test.

diff --git a/libstdc++-v3/config/abi/pre/gnu.ver b/libstdc++-v3/config/abi/pre/gnu.ver
index 92af1aec7b4..788c2e0303c 100644
--- a/libstdc++-v3/config/abi/pre/gnu.ver
+++ b/libstdc++-v3/config/abi/pre/gnu.ver
@@ -495,7 +495,7 @@ GLIBCXX_3.4 {
     _ZNSo8_M_writeEPKc[ilx];
     _ZNSo3put*;
     _ZNSo[5-9][a-z]*;
-    _ZNSolsE*[^g];
+    _ZNSolsE*[^Dg];
 
     # std::basic_ostream<wchar_t>
     _ZNSt13basic_ostreamIwSt11char_traitsIwEEC[12]Ev;
@@ -509,7 +509,7 @@ GLIBCXX_3.4 {
     _ZNSt13basic_ostreamIwSt11char_traitsIwEE5writeEPKw*;
     _ZNSt13basic_ostreamIwSt11char_traitsIwEE6sentry*;
     _ZNSt13basic_ostreamIwSt11char_traitsIwEE8_M_writeEPKw[ilx];
-    _ZNSt13basic_ostreamIwSt11char_traitsIwEElsE*[^g];
+    _ZNSt13basic_ostreamIwSt11char_traitsIwEElsE*[^Dg];
 
     # std::ostream operators and inserters
     _ZSt4end[ls]I[cw]St11char_traitsI[cw]EERSt13basic_ostream*;
@@ -2223,6 +2223,10 @@ GLIBCXX_3.4.26 {
     _ZNSt10filesystem7__cxx1128recursive_directory_iteratoraSEOS1_;
     _ZNSt10filesystem7__cxx1128recursive_directory_iteratorppEv;
 
+    # basic_ostream::operator<<(nullptr_t)
+    _ZNSolsEDn;
+    _ZNSt13basic_ostreamIwSt11char_traitsIwEElsEDn;
+
 } GLIBCXX_3.4.25;
 
 # Symbols in the support library (libsupc++) have their own tag.
diff --git a/libstdc++-v3/include/std/ostream b/libstdc++-v3/include/std/ostream
index 50c99b25d58..2541d978886 100644
--- a/libstdc++-v3/include/std/ostream
+++ b/libstdc++-v3/include/std/ostream
@@ -245,6 +245,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       operator<<(const void* __p)
       { return _M_insert(__p); }
 
+#if __cplusplus >= 201703L
+      __ostream_type&
+      operator<<(nullptr_t)
+      { return *this << "nullptr"; }
+#endif
+
       /**
        *  @brief  Extracting from another streambuf.
        *  @param  __sb  A pointer to a streambuf
diff --git a/libstdc++-v3/src/c++17/Makefile.am b/libstdc++-v3/src/c++17/Makefile.am
index 4200f7f8259..1a00770081e 100644
--- a/libstdc++-v3/src/c++17/Makefile.am
+++ b/libstdc++-v3/src/c++17/Makefile.am
@@ -41,6 +41,8 @@ endif
 if ENABLE_EXTERN_TEMPLATE
 # XTEMPLATE_FLAGS = -fno-implicit-templates
 inst_sources = \
+	ostream-inst.cc \
+	string-inst.cc \
 	$(extra_string_inst_sources)
 else
 # XTEMPLATE_FLAGS =
@@ -52,7 +54,6 @@ sources = \
 	fs_ops.cc \
 	fs_path.cc \
 	memory_resource.cc \
-	string-inst.cc \
 	$(extra_fs_sources)
 
 vpath % $(top_srcdir)/src/c++17
diff --git a/libstdc++-v3/src/c++17/ostream-inst.cc b/libstdc++-v3/src/c++17/ostream-inst.cc
new file mode 100644
index 00000000000..b2fbafcef91
--- /dev/null
+++ b/libstdc++-v3/src/c++17/ostream-inst.cc
@@ -0,0 +1,42 @@
+// std::ostream instantiations for C++17 -*- C++ -*-
+
+// Copyright (C) 2019 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/>.
+
+//
+// ISO C++ 14882:2017 28  Input/output library
+//
+
+#include <ostream>
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+template basic_ostream<char>& basic_ostream<char>::operator<<(nullptr_t);
+
+#ifdef _GLIBCXX_USE_WCHAR_T
+template basic_ostream<wchar_t>& basic_ostream<wchar_t>::operator<<(nullptr_t);
+#endif
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
diff --git a/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_other/char/lwg2221.cc b/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_other/char/lwg2221.cc
new file mode 100644
index 00000000000..b4ff52b7d2c
--- /dev/null
+++ b/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_other/char/lwg2221.cc
@@ -0,0 +1,9 @@
+// { dg-options "-std=gnu++17 -fno-inline" }
+// { dg-do link }
+
+#include <iostream>
+
+int main()
+{
+  std::cout << nullptr << std::endl;
+}