[PATCH v2] Add TEST_CC and TEST_CXX support

[Sam James]

"H.J. Lu" <hjl.tools@gmail.com> writes:

> On Fri, Dec 6, 2024 at 7:35 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>>
>> Support testing glibc build with a different C compiler or a different
>> C++ compiler with
>>
>> $ ../glibc-VERSION/configure TEST_CC="gcc-6.4.1" TEST_CXX="gi++-6.4.1"

gi++ -> g++

>>
>> 1. Also check compiler options with TEST_CC and TEST_CXX.
>> 2. Add check and xcheck targets to Makefile.in and override build compiler
>> options with ones from TEST_CC and TEST_CXX.
>>
>
> Here is the v2 patch.  Tested with GCC 14.2.1 build and
> GCC 11.2.1 test on x86-64.  I got
>
> FAIL: math/test-float64x-fpclassify
> FAIL: math/test-float64x-isinf
> FAIL: math/test-float64x-isnan
> FAIL: math/test-ldouble-fpclassify
> FAIL: math/test-ldouble-isinf
> FAIL: math/test-ldouble-isnan
>
> More changes in configure.ac under sysdeps are
> needed to support older GCCs.

Please fix '==' use in configure.ac; configure is run with #!/bin/sh and
hence must be POSIX compatible (i.e. change it to '=', or better, use
AS_IF).

Ideally please quote arguments to the macros too like AC_CHECK_PROGS.

I like the idea.