Re: CVS commit: src/tools/gcc

["David H. Gutteridge" <david%gutteridge.ca@localhost>]

On 2024-06-16 13:01, matthew green wrote:
> "David H. Gutteridge" writes:
>
> > Module Name:    src
> > Committed By:    gutteridge
> > Date:        Sun Jun 16 16:03:30 UTC 2024
> >
> > Modified Files:
> > src/tools/gcc: Makefile
> >
> > Log Message:
> > 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.)

I can certainly simply revert for now, if you prefer.

I'm a little confused by your answer, as there are pre-existing bits
that already do this or something similar. (Well, or intend to.)

tools/isl/Makefile has:

# XXX this gets lost some how.  Not portable.
HOST_CXXFLAGS+=	-std=gnu++17

A different example is from tools/Makefile.gmakehost:

# Disable use of pre-compiled headers on Darwin.
BUILD_OSTYPE!= uname -s
HOST_COMPILER_CLANG!= if ${HOST_CC} --version | grep -q -s clang; then 
echo yes; else echo no; fi
.if ${HOST_COMPILER_CLANG} == "yes"
HOST_CFLAGS+=-O2 -no-cpp-precomp
.endif

The latter is intended to deal with a different sort of issue, but I
see it as being related in terms of reaching over and injecting its
own HOST_* values. If we say "the host should sort out its own issues",
effectively, then I don't see why that would be there, either. (There
is more like that elsewhere.)

I realize I supplied a "GCC-style" argument that not all compilers
will accept. I don't know what compilers would be viable now other than
GCC and Clang?

The goal is to be able to set different compiler flags on a per
component basis. There could be other components that don't want the
same standard forced (or whatever). To your point, we could have
something that tests and sets a make variable that's conditionally
applied down in a particular component.

Regards,

Dave