Re: [PATCH] build: avoid link failure on systems using gnulib's fcntl but not open

[Jim Meyering]

Bruno Haible wrote:
> Replying to Jim I wrote:
>> >       "_rpl_open", referenced from:
>> >           _grepfile in grep.o
>> The situation in the 'grep' package is as follows:
>>   - The main part, in lib/, has the module 'fcntl' and therefore
>>     implicitly 'fcntl-h', but not the 'open' module.
>>   - The tests part, in gnulib-tests/, has the module 'open', as a
>>     dependency from 'dup2-tests'.
>>   - The presence of the 'open' module is indicated through an
>>     AC_SUBSTed variable GNULIB_OPEN. There is only one GNULIB_OPEN
>>     for the entire package, and it is set to 1.
>>   - Therefore the lib/fcntl.h replacement defines "#define open rpl_open".
>>
>> I wouldn't say that it's a bug in gnulib.
>> It's a limitation of gnulib that you cannot decide to not use a module in
>> the main part but use it in the tests. If you really wanted that, you
>> would need a setup with two different configure.ac files, one for the
>> main part and one for the tests.
>
> But the user may be using open() in the main part, in lib/, without wanting
> to use gnulib's 'open' module. We document for each module the list of
> problems that it fixes. It's not because that dup2-tests requires an open()
> function with a special workaround that the main part, in lib/, would need
> it as well.
>
> So I think it's a bug in gnulib.
...

Nice work.
I'm glad you took the time to solve this properly.