Re: manywarnings and -f options

[Jim Meyering]

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.