This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Dealing with compilers that pretend to be GCC


Hello,

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.

I had the following macro to determine whether plug-in support is
available:

  https://gforge.inria.fr/scm/viewvc.php/trunk/m4/gcc.m4?view=markup&revision=5169&root=starpu&pathrev=5202

The macro is fairly elaborate.  Yet, ICC 12.0.1 and Clang 3.4 both pass
the test, because:

  - They support â--versionâ;

  - They define â__GNUC__â, which defeats Autoconfâs
    â_AC_LANG_COMPILER_GNUâ.

  - They support â-print-file-nameâ, and have â-print-file-name=pluginâ
    return GCCâs (!) plug-in header directory.  To that end, ICC simply
    runs âgcc -print-file-name=pluginâ, while Clang appears to be doing
    some guesswork.

It turns out that ICC manages to build a working GCC plug-in, so after
all, it may be âentitledâ to define â__GNUC__â, in a broad sense.

Conversely, Clang doesnât support several GNU extensions, such as nested
functions, so it quickly fails to compile code.

Based on that, I modified my feature test like this:

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

I donât see what can be done on âourâ side (perhaps Autoconfâs feature
test could be strengthened, but how?), but I wanted to document this
state of affairs.

Thanks,
Ludoâ.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]