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

[Rainer Orth]

Hi Jonathan,

> 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.

this patch broke Solaris bootstrap:

ld: fatal: libstdc++-symbols.ver-sun: 7117: symbol 'std::basic_ostream<char, std::char_traits<char> >::operator<<(decltype(nullptr))': symbol version conflict
ld: fatal: libstdc++-symbols.ver-sun: 7119: symbol 'std::basic_ostream<wchar_t, std::char_traits<wchar_t> >::operator<<(decltype(nullptr))': symbol version conflict

ld: fatal: libstdc++-symbols.ver-sun: 7117: symbol '_ZNSolsEDn': symbol version conflict
ld: fatal: libstdc++-symbols.ver-sun: 7119: symbol '_ZNSt13basic_ostreamIwSt11char_traitsIwEElsEDn': symbol version conflict

Again, there were two matches for those two symbols:

  GLIBCXX_3.4
    ##_ZNSolsE*[^Dg] (glob)
    _ZNSolsEDn;
  GLIBCXX_3.4.26
    ##_ZNSolsEDn (glob)
    _ZNSolsEDn;

  GLIBCXX_3.4
    ##_ZNSt13basic_ostreamIwSt11char_traitsIwEElsE*[^Dg] (glob)
    _ZNSt13basic_ostreamIwSt11char_traitsIwEElsEDn;
  GLIBCXX_3.4.26
    ##_ZNSt13basic_ostreamIwSt11char_traitsIwEElsEDn (glob)
    _ZNSt13basic_ostreamIwSt11char_traitsIwEElsEDn;

ISTM that the patterns were backwards.  The following patch fixes this
and allowed i386-pc-solaris2.11 bootstrap to complete without
regressions relative to the last successful one.

Ok for mainline?

	Rainer

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University


2019-01-10  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	* config/abi/pre/gnu.ver(GLIBCXX_3.4): Fix pattern.
	(GLIBCXX_3.4.21): Likewise.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: sol2-v3-lwg2221.patch
Type: text/x-patch
Size: 983 bytes
Desc: not available
URL: <http://gcc.gnu.org/pipermail/libstdc++/attachments/20190110/84586288/attachment.bin>