Re: AX_PROG_CC_FOR_BUILD should use CFLAGS, etc. in non-crossbuilds

[Paolo Bonzini]

Il 02/01/2014 17:46, Ryan Lortie ha scritto:
> hi,
> 
> Please excuse (and redirect) me if this is not the correct place to file
> this bug.
> 
> The AX_PROG_CC_FOR_BUILD macro in autoconf-archive defines the variables
> CFLAGS_FOR_BUILD, CPPFLAGS_FOR_BUILD and LDFLAGS_FOR_BUILD so that
> people can build executables on the build machine with different
> compiler flags when cross-compiling.
> 
> When not cross-compiling, however, this is a bit of an anti-feature
> because it requires the user to explicitly set these variables in
> addition to the usual CFLAGS, CPPFLAGS, LDFLAGS.
> 
> I consider that there are probably two approaches to fixing it.
> 
> First approach (code added to the top of the macro):
> 
> if test "$cross_compiling" = "no"; then
>        if test -n "$CFLAGS"; then
>                CFLAGS_FOR_BUILD=$CFLAGS
>        fi
>        if test -n "$CPPFLAGS"; then
>                CPPFLAGS_FOR_BUILD=$CPPFLAGS
>        fi
>        if test -n "$LDFLAGS"; then
>                LDFLAGS_FOR_BUILD=$LDFLAGS
>        fi
> fi
> 
> ie: if we see that we are not cross-compiling, initialise the values of
> the _FOR_BUILD variables from their host counterparts (since host ==
> build).
> 
> Second approach:
> 
> if test -z "$CFLAGS_FOR_BUILD" -a -n "$CFLAGS"; then
>       CFLAGS_FOR_BUILD="$CFLAGS"
> fi
> if test -z "$CPPFLAGS_FOR_BUILD" -a -n "$CPPFLAGS"; then
>       CPPFLAGS_FOR_BUILD="$CPPFLAGS"
> fi
> if test -z "$LDFLAGS_FOR_BUILD" -a -n "$LDFLAGS"; then
>       LDFLAGS_FOR_BUILD="$LDFLAGS"
> fi
> 
> ie: always initialise these variables from their host counterparts
> except in the case that they are already explicitly set.

I think the second approach is wrong.  The $cross_compiling test is
necessary.  But you can do: initialise the variables from their host
counterparts in the non-cross-compiling case, but not in the case that
they are already explicitly set.

What do you think?

Paolo