From: Christian Franke <Christian.Franke@t-online.de>
To: cygwin@cygwin.com
Subject: Re: Updated: gcc-5.2.0-1 (Test x86/x86_64)
Date: Tue, 06 Oct 2015 16:26:00 -0000 [thread overview]
Message-ID: <5613F632.1080205@t-online.de> (raw)
In-Reply-To: <560D2F6D.90608@gmail.com>
cyg Simple wrote:
> On 9/30/2015 7:36 PM, David Stacey wrote:
>> On 30/09/15 23:34, JonY wrote:
>>> On 10/1/2015 00:05, David Stacey wrote:
>>>> On 30/09/15 12:15, JonY wrote:
>>>>> gcc-5.2.0-1 has been uploaded for 32bit and 64bit Cygwin.
>>>>>
>>>>> This is the first series of the 5.x releases, and should be considered
>>>>> as experimental as such.
>>>> Have you managed to work around the ABI change in gcc-5 [1], or will
>>>> this require a mass rebuild at the point gcc-5 becomes 'current'?
>>>>
>>>> [1] -http://developerblog.redhat.com/2015/02/05/gcc5-and-the-c11-abi/
>>> As far as I know, every gcc release will break C++ ABI, so it would mean
>>> rebuilding everything C++.
>> According to the Red Hat blog above, the last time g++ caused an ABI
>> change was back in the 3.x days, so it hasn't happened for a while. Ah
>> well, we have maintainers for most packages in Cygwin, so we'll have to
>> co-ordinate a rebuild.
> Regardless, JonY is correct. Every C++ release, regardless of the
> vendor, causes an ABI break with shared libraries and the naming of the
> object elements (mangled names).
Probably not in this 4.X -> 5.X case. Otherwise the new cygstdc++-6.dll
should IMO be renamed to -6.1, -7 or similar.
A diff of exported symbols of cygstdc++-6.dll 4.9.3-1 and 5.2.0 shows
that the new version only adds new symbols.
Results of a quick build check with smartmontools package:
- Existing package which was built with g++ 4.9.2 runs with 5.2.0
cygstdc++-6.dll and cyggcc_s-1.dll.
- A rebuild with g++ 5.2.0 does not run with 4.9.3 cygstdc++-6.dll due
to missing symbols. This is as expected because 5.X adds a new C++11
conforming std::string which is used by default
(https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html).
- A rebuild with g++ 5.2.0 and CXXFLAGS=-D_GLIBCXX_USE_CXX11_ABI=0 runs
with old 4.9.3 cygstdc++-6.dll and cyggcc_s.dll.
So there is probably no need to rebuild existing C++ packages.
BTW: segment sizes differ considerably:
$ size */smartctl.exe
text data bss dec hex filename
459725 6956 66320 533001 82209 gcc-4-old-strings/smartctl.exe
451525 7424 66260 525209 80399 gcc-5-new-strings/smartctl.exe
517337 8912 66196 592445 90a3d gcc-5-old-strings/smartctl.exe
Christian
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next prev parent reply other threads:[~2015-10-06 16:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <560BC46D.3060500@gmail.com>
2015-09-30 16:06 ` David Stacey
2015-09-30 22:34 ` JonY
2015-09-30 23:36 ` David Stacey
2015-10-01 13:04 ` cyg Simple
2015-10-06 16:26 ` Christian Franke [this message]
2015-10-06 17:51 ` Ken Brown
2015-10-06 22:12 ` David Stacey
2015-10-07 7:45 ` Csaba Raduly
2015-10-06 22:20 ` David Stacey
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