[cfe-dev] RFC: switch default C language mode from gnu99 to gnu11

[David Blaikie]

On Thu, Oct 16, 2014 at 1:15 PM, Chandler Carruth <chandlerc at google.com>
wrote:

>
> On Thu, Oct 16, 2014 at 12:58 PM, Richard Smith <richard at metafoo.co.uk>
> wrote:
>
>>  -- Add a buildbot that runs all tests with the default language mode set
>> to each possible value
>
>
> If you're going to do this, I would *much* rather see the test
> infrastructure changed so that all are exercised by doing 'check-clang'. I
> think it would be really bad to create yet another trap for developers
> where tests pass locally but fail on the bots. =/
>

I was going to say, this seems similar to the idea we've had to run all the
LLVM tests (& maybe Clang codegen) with all the supported targets - the
tests are meant to be portable (& fail on buildbots when they aren't) and
could actually be tested locally on the same machine if we had a mode in
which we could run that.

But I'm not sure it should be the default - it seems pretty low-value to
run all these flavors for every test run, yet nice to have the option
should there be a bot failure (or to reduce the unique coverage from having
different achitecture bots - most of it should be testable on just a single
machine) to easily reproduce it locally, or do some more thorough testing
if there's otherwise reason to believe there's a portability/language
version-y problem.

(apologies for conflating these two ideas if you believe there's a good
reason for them to be handled differently, but just where my mind went at
the mention of this stuff)

Essentially I see running all these flavors as akin to running the test
suite - it's an extra level of testing but I wouldn't make it the default
as I don't think it hits the cost/benefit tradeoff for interactive
development. Numbers would be necessary/helpful to back that up (or refute
it).

- David


>
> If its too expensive to do this for *all* tests w/o a standard specified,
> we should cherry pick the ones we want to run in all modes and just
> replicate the RUN lines with a script.
>
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