RFR: 8323672: Suppress unwanted autoconf added flags in CC and CXX [v4]

[Julian Waters]

On Thu, 18 Jan 2024 13:59:30 GMT, Erik Joelsson <erikj at openjdk.org> wrote:

> > What fun, I just found out that omitting the call to AC_PROG_CC and AC_PROG_CXX has no effect, and they're _still_ called magically from somewhere by autoconf even if you don't call them. I'm genuinely at a loss for words :)
> 
> If I'm to guess, I think this is caused by AC_PROG_* being defined as AC_DEFUN_ONCE and every other autoconf macro that uses compilers for checks will implicitly call AC_PROG_* first if it hasn't been called yet. My understanding of these implicit calls is to make a more declarative programming style possible.

It's not so much the AC_DEFUN_ONCE, but actually due to other autoconf macros calling AC_REQUIRE([AC_PROG_CC]) and AC_REQUIRE([AC_PROG_CXX]), for instance our calls to AC_PROG_CPP and AC_PROG_CXXCPP will cause AC_PROG_CC and AC_PROG_CXX respectively to be implicitly called

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PR Comment: https://git.openjdk.org/jdk/pull/17401#issuecomment-1898554535