Hello,

For -mrtp on VxWorks 6.9, at least inttypes.h ends up #including
system headers checking that _BITS_BYTES is 8, which the system yvals.h
defines. We do pre-include _yvals.h ahead of inttypes.h for this kind of
purpose, but it currently assumes that only VxWorks >= 7 provides yvals.h.

This results in unexpected configure checks failures, complaining about
_BITS_BYTES not being 8, spotted while inspecting libstdc++ config.log for
unrelated reasons.

This change relaxes the guard in _yvals.h to include yvals.h for
__RTP__ in addition to version >= 7.

I had good builds and test results with this in-house for gcc-11 based
toolchains for a variety of targets. I checked that a build for vx6.9
passes with mainline sources and verified that the spurious configure
test failures are gone.

Will commit shortly.

I'm not 100% sure about the situation on VxWorks 5. This is easy to
adjust if need be.

Olivier


2021-12-13  Olivier Hainque  <hainque@adacore.com>

        * config/vxworks/_yvals.h: #include yvals.h also if
        defined(__RTP__).