Re: [patch] Fix unused static symbols so they're not dropped by clang

Doug Evans
2014-04-11T19:32:48Z

On Fri, Apr 11, 2014 at 11:23 AM, Doug Evans <dje@google.com> wrote:
> On Thu, Apr 10, 2014 at 11:51 PM, David Blaikie <dblaikie@gmail.com> wrote:
>> Several tests used file-static functions and variables that were not
>> referenced by the code. Even at -O0, clang omits these entities at the
>> frontend so the tests fail.
>>
>> Since it doesn't look like these tests needed this functionality for
>> what they were testing, I've modified the variables/functions to
>> either be non-static, or marked them with __attribute__((used)).
>>
>> If it's preferred that I use the attribute more pervasively, rather
>> than just making the entities non-static, I can provide a patch for
>> that (or some other preferred solution). There's certainly precedent
>> for both (non-static entities and __attribute__((used)) in the
>> testsuite already and much more of the former than the latter).
>>
>> I have commit-after-review access, so just looking for sign-off here.
>
> Yikes.
>
> This is becoming more and more painful (not your fault of course!).
> I can imagine this being a never ending source of regressions.
>
> Does clang perchance have a -O0-and-yes-I-really-mean-O0 option?

Failing that,

making the entries non-static without adding a comment to explain why
things are the way they are will leave things in a more fragile state,
and if we're going to add a comment we might just as well use an
attribute throughout I guess.
However using the attribute is, technically, more complicated than
that because we shouldn't unnecessarily break testing with other
compilers.
That suggests putting the attribute in a macro in a header protected
by appropriate #ifdefs.
The testsuite doesn't yet have a single location for such headers
(testsuite/include or some such, though there is already testsuite/lib
(cough) but if it's just for the one header ...).