Re: [doc] MAKEOVERRIDES is undocumented

[Jeffrey Walton]

On Mon, Dec 19, 2022 at 10:45 AM Alejandro Colomar
<alx.manpages@gmail.com> wrote:
>
> I needed to use MAKEOVERRIDES for updating a pkgconf (.pc) file.  I want it to
> have the correct directory variables as used when building/installing the
> library, so if the user specifies 'includedir=/foo/bar' in the command line, 
> the
> .pc file should be updated with that info.
>
> The rule I had to use is:
>
> $(_LIB_pc): $(_LIB_pc_u) Makefile | $$(@D)/
>         $(info  SED             $@)
>         sed 's/Version:.*/Version: $(DISTVERSION)/' <$< >$@
>         sed -i 's,prefix=.*,prefix=$(prefix),' $@
> ifneq ($(filter includedir=%,$(MAKEOVERRIDES)),)
>         sed -i 's,includedir=.*,includedir=$(includedir),' $@
> endif
>
> As you can see, I need to check if it was overridden in the command line
> (otherwise, the default 'includedir=${prefix}/include' in the .pc file is 
> fine).
>   And then I do override it.

I don't think you need to go to extremes. Just check if includedir is
set. If so, use it. If not, use the default of $prefix/include.

You can do this in your makefile [1,2]:

   ifeq ($(includedir),)
     includedir := $(prefix)/include
     PC_INCLUDEDIR = $${prefix}/include
   else
     PC_INCLUDEDIR = $(includedir)
   endif

    myconfig.pc:
        ...
       @echo 'includedir=$(PC_INCLUDEDIR)' >> myconfig.pc

Jeff

[1] https://github.com/weidai11/cryptopp/blob/master/GNUmakefile#L202
[2] https://github.com/weidai11/cryptopp/blob/master/GNUmakefile#L1544