Re: another manywarnings failure

[Eric Blake]

On 09/06/2012 12:07 AM, Jim Meyering wrote:
> Eric Blake wrote:
> 
>> I compiled on FreeBSD 8.2 (gcc 4.2.1), and when I updated to the latest
>> gnulib, I started to see the following in config.log when running
>> ./configure CFLAGS=-g:
>>

> When you configure with one set of warning options and later
> build with another, as with your "make CFLAGS=-g", you're
> short-circuiting the build tests.  When I do that, I
> simply turn off -Werror and ignore the warnings:
> 
>     make CFLAGS=-g WERROR_CFLAGS=

But note that I did:

./configure CFLAGS=-g

at the outset.  Yes, I'm aware that _if_ you override CFLAGS at make
time, you may have to also disable warnings at that time as well.  But
here, I'm talking about the case where I configured optimization to be
off without needing to override CFLAGS at make time; that is, in a
situation where we CAN run a configure test to see whether the warning
will even be effective.

> 
> Of course, you could simply rerun configure with CFLAGS=-g,

Which is what I did...

> and it would test each -W option individually...

except that each -W option individually succeeds.  -Wuninitialized only
warns, not errors out, on this particular gcc 4.2.1 build.  You _have_
to test the combination of '-Wuninitialized -Werror' but no -O, in order
to hit the failure.  But I'm not sure how best to modify manywarnings.m4
to do that testing.  Then again, we've already special-cased
-Wno-missing-field-initializer to work around gcc infelicities, so I
guess I could enhance the module by adding another test along those lines.

-- 
Eric Blake   address@hidden    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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