Re: Dealing with compilers that pretend to be GCC

[ludovic dot courtes at inria dot fr (Ludovic Courtès)]

Hi Ducan,

Duncan Sands <baldrick@free.fr> skribis:

>> A number of compilers claim to be GCC, without actually being GCC.  This
>> has come to a point where they can hardly be distinguishedâuntil one
>> actually tries to use them.
>
> this suggests that you shouldn't be testing for GCC, and instead should be
> testing for support for particular features.  For example, to know if nested
> functions are supported you would have your configure script compile a mini
> program that uses nested functions.

Yes.  The macro I posted is a feature test: it tests for plug-in header
availability, and the availability of several GCC internal types and
declarations.

When I noticed that Clang doesnât support nested functions, I added that
to the test:

  https://gforge.inria.fr/scm/viewvc.php/trunk/m4/gcc.m4?root=starpu&r1=5169&r2=5203

Yet, I canât reasonably add a feature test for each GNU extension that
GCCâs headers or my own code use.  Maybe tomorrow Clang will support
nested functions, while still lacking support for some other extension
thatâs needed.

Thanks,
Ludoâ.