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Re: manywarnings and -f options
From: |
Simon Josefsson |
Subject: |
Re: manywarnings and -f options |
Date: |
Sun, 04 Dec 2011 12:32:20 +0100 |
User-agent: |
Gnus/5.110018 (No Gnus v0.18) Emacs/24.0.91 (gnu/linux) |
Jim Meyering <address@hidden> writes:
> Eric Blake wrote:
>> On 12/03/2011 09:00 AM, Simon Josefsson wrote:
>>> What does -funit-at-a-time really do? My gcc 4.4 manual says:
>>>
>>> `-funit-at-a-time'
>>> This option is left for compatibility reasons. `-funit-at-a-time'
>>> has no effect, while `-fno-unit-at-a-time' implies
>>> `-fno-toplevel-reorder' and `-fno-section-anchors'.
>>>
>>> Enabled by default.
>>
>> That's the case for 4.4 and later. But in gcc 4.3, it was not
>> unconditionally enabled, and as I said earlier, at least coreutils ran
>> into a situation where gcc 4.3. failed to compile at -Werror because
>> -Wdisabled-optimization warned that -fno-unit-at-a-time was required,
>> which warning turned into an error.
>>
>> At this point, gcc 4.3 is slowly phasing out; most Linux distros and
>> Cygwin have moved on to newer compilers, where the problem is less
>> likely to happen.
>
> IMHO, we should treat --enable-gcc-warnings as something that must work
> well with the latest stable version of gcc (currently 4.6) and recent
> glibc headers. Trying to accommodate older versions of gcc does not seem
> worthwhile. Just tell people who use old versions of gcc not to use
> --enable-gcc-warnings, or even detect that and turn it off automatically.
I think this is a good approach: I wouldn't want workarounds for issues
in old gcc in manywarnings.m4. Manywarnings is a maintainer tool, and
maintainers can be required to have newer tools than users, so
manywarnings could require more recent tools. However, personally I
still use gcc 4.4 on my primary development machine, so if it isn't
difficult to support it, I'd prefer that.
/Simon