Re: manywarnings and -f options

[Jim Meyering]

Simon Josefsson wrote:
> 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.

That is reasonable, since you'll be motivated to address any problem
that is specific to your aging, er... "stable" environment ;-)

Besides, if it just-works even with gcc-4.4, we'll avoid at least
a few bug reports.