On 21 February 2017 at 14:58, Bruno Haible <br...@clisp.org> wrote: > Hi Reuben, > > This looks reasonable: Since a project can use both gcc and g++ and since > the > desired warning options for gcc and g++ are likely different, it's good to > have different macros, that set different variables (WARN_CFLAGS vs. > WARN_CXXFLAGS). >
Thanks very much for the detailed guidance.
Going further, there is no real benefit of having manywarnings-cxx a
> different
> module. Since an m4 macro that is not invoked does not contribute to the
> size
> nor the execution time of the 'configure' script, I would just add the two
> new macros gl_MANYWARN_ALL_GXX and gl_CXX_WARN_ADD - in manywarnings.m4
> and warnings.m4, respectively.
>
Done.
> However, two things are important:
> - That the name of the *_cv_* variables are different in the C++ macro
> than in the C macro.
>
Done.
> - That you invoke AC_LANG_PUSH([C++]) at the beginning and
> AC_LANG_POP([C++])
> at the end of the macro, so that AC_LANG_SOURCE invocations do the
> right
> thing.
>
Done, but do I also need to add an AC_LANG_PUSH/POP([C]) at the beginning
and end of gl_MANYWARN_ALL_GCC? If not, why not? (Is C assumed as the
default?)
Please also fix the AC_REQUIRE([gl_UNKNOWN_WARNINGS_ARE_ERRORS]) invocation
> in gl_WARN_ADD and gl_CXX_WARN_ADD. Since this macro expands to different
> code after AC_LANG_PUSH([C++]) than after AC_LANG_PUSH([C]), it is wrong
> to just AC_REQUIRE it. Needs to be a bit more intelligent.
>
> Look at how _AC_LANG_ABBREV and _AC_LANG_PREFIX can be used. Maybe
> libtool.m4,
> which also plays around with AC_LANG, gives you some hint about this.
>
I didn't fully understand this bit. I see that
_AC_LANG_ABBREV/_AC_LANG_PREFIX are used to inject the name of the language
into the names of variables. I see that gl_UNKNOWN_WARNINGS_ARE_ERRORS
changes depending on the language because gl_COMPILER_OPTION_IF changes.
(By the way, can we now assume autoconf 2.64 (of July 2009) or newer and
hence quote gl_Warn, as per the comment, there?)
Since gl_UNKNOWN_WARNINGS_ARE_ERRORS is therefore language-dependent, that
makes me think it needs to be called, not AC_REQUIREd, by
gl_{CXX_,}_WARN_ADD (because the language might change each time), but if
it were that simple, you'd've said so. So I'm not sure what else is needed…
I attach the latest state of play, which consists simply of updated
versions of manywarnings.m4 and warnings.m4, in place of the new files I
had before. (To test them I have simply placed them in a gnulib patch
directory which is applied by bootstrap; I love how simple it is!)
--
http://rrt.sc3d.org
manywarnings.m4
Description: application/m4
warnings.m4
Description: application/m4
