Re: CVS commit: src/tools/gcc

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

> Date: Mon, 17 Jun 2024 03:01:55 +1000
> from: matthew green <mrg%eterna23.net@localhost>
> 
> "David H. Gutteridge" writes:
> > Module Name:	src
> > Committed By:	gutteridge
> > Date:		Sun Jun 16 16:03:30 UTC 2024
> >
> > tools/gcc/Makefile: force std=c++11 for GCC 12 builds
> >
> > GCC >= 11 now requires C++11 to build. Impacted individual components
> > vary whether they test for if std=c++11 is the default or has to be
> > passed. Regardless, our build infrastructure applies its own overrides.
> > Force this setting so that we can still build on NetBSD 8.x hosts (and
> > probably 7.x, too). Build tested on NetBSD 8.3.
> 
> i'm not sure i like this.  the build environment is expected to
> provide a valid compiler, and the above assumes how the compiler
> works.
> 
> if we really want to support this without user-env setup, then
> i think a confiure test (from tools/compat) would be better than
> forcing this option here directly.
> 
> (also note this is not the first time this sort of issue has
> arrived, and we always asked the build-env provider to fix it,
> but i'm not against eg, the configure test idea.)

How is the host C++ compiler supposed to know that we are asking it to
compile C++11 and not C++98 or C++17?

gcc's configure scripts search for a way to pass this information to
the host compiler (e.g., AX_CXX_COMPILE_STDCXX).  I'm fuzzy on how
these are supposed to work but it looks like maybe the existing
configure tests are not getting used for some reason.