Re: PKG-Config not enabled.

[Thomas Dickey]

On Sat, Oct 09, 2021 at 09:43:23AM +0200, Pascal wrote:
> 
> > Le 3 oct. 2021 à 22:25, Thomas Dickey <dickey@his.com> a écrit :
> > 
> > On Sun, Oct 03, 2021 at 07:09:32PM +0200, Pascal wrote:
> >> Hello,
> >> 
> >> When configuring ncurses, I got:
> >> ...
> >> ** Configuration summary for NCURSES 6.2 20210925:
> >> ...
> >> pkg-config directory: no
> >> 
> >> The last line seems to indicate that pkg-config is not enabled.
> > 
> > not exactly: it indicates that the configure script was not able to
> > find the library-directory for pkg-config.  ncurses' configure script
> > looks for this information so that it knows where to install ".pc" files.
> > 
> > (One of the design defects of pkg-config is that it's missing options for
> > querying the tool for _its_ default configuration, which is aggravated by
> > packagers putting it into interesting places).
> > 
> > The configure script attempts to find that in CF_WITH_PKG_CONFIG_LIBDIR,
> > but that may fail.
> 
> Thanks Thomas,
> 
> it's ok now.
> FYI, on my configuration, ncurses pc files are created in 
> $prefix/share/pkgconfig.
> One might expected in $prefix/lib/pkgconfig.

hmm: "lib" is conventionally used for binaries, and "share" for text.

On this (Debian) system, the manual page for pkg-config uses both:

       PKG_CONFIG_LIBDIR
              Replaces  the  default  pkg-config  search  directory,   usually
              /usr/lib/pkgconfig:/usr/share/pkgconfig.

...and
       pkg-config retrieves information about packages from  special  metadata
       files.  These  files  are named after the package, and has a .pc exten‐
       sion.   On  most  systems,  pkg-config  looks  in   /usr/lib/pkgconfig,
       /usr/share/pkgconfig,     /usr/local/lib/pkgconfig     and     /usr/lo‐
       cal/share/pkgconfig for these files.  It will additionally look in  the
       colon-separated  (on  Windows, semicolon-separated) list of directories
       specified by the PKG_CONFIG_PATH environment variable.

and the configure script actually looks in both places, but checks
"share" first, with a comment about 2014 (which would be from Debian 5
or 6 -- we've moved on a little).

I don't see a way to ask pkg-config what its built-in search order happens
to be.  Previous discussion in this area has mostly dealt with the
interesting variations that packagers have done for cross-compilers,
which haven't been limited to just changing the $prefix.

Before changing the order, I'd check if that difference in order was due
to my assumption that pkg-config followed convention, or some change in
pkg-config, and how that maps to various systems :-)

-- 
Thomas E. Dickey <dickey@invisible-island.net>
https://invisible-island.net
ftp://ftp.invisible-island.net

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