[Bug other/79885] --with-build-sysroot= does not get honored throughout the build (fix-includes, CPP, CXXCPP, configure-stage2)

[jeremyhu at macports dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79885

Jeremy Huddleston Sequoia <jeremyhu at macports dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|fix-includes does not honor |--with-build-sysroot= does
                   |the value passed to         |not get honored throughout
                   |--with-build-sysroot=,      |the build (fix-includes,
                   |looks for /usr/include      |CPP, CXXCPP,
                   |instead of looking within   |configure-stage2)
                   |the SDK                     |

--- Comment #7 from Jeremy Huddleston Sequoia <jeremyhu at macports dot org> ---
Retitled to make the issue more clear/generic.

Note that using --with-sysroot, I'm able to get a built compiler, but the
result ends up using the configured sysroot as its default sysroot (as one
would expect based on the documentation for --with-sysroot).

My understanding is that --with-build-sysroot should behave the same as
--with-sysroot *except* that the installed compiler's default is modified by
--with-sysroot and not modified by --with-build-sysroot.