bug#18926: cmake-build-system should set CMAKE_INSTALL_LIBDIR and CMAKE_PREFIX_PATH

[ludo@gnu.org (Ludovic Courtès)]

宋文武 <iyzsong@gmail.com> skribis:

> Ludovic Courtès <ludo@gnu.org> writes:
>
>> 宋文武 <iyzsong@gmail.com> skribis:
>>
>>> if CMAKE_INSTALL_LIBDIR not set to `lib`, GNUInstallDirs.cmake will install
>>> libraries files to $out/lib64.
>>
>> I found several CMake-built libraries on x86_64 (graphite2, openjpeg,
>> qjson) that all use lib/, not lib64/.
>>
>> Then I found one counterexample, libftdi; however, setting
>> CMAKE_INSTALL_LIBDIR=lib doesn’t make any different: it still installs
>> libraries in $out/lib64.  Any idea?
> libftdi (not using GNUInstallDirs.cmake) handle this itself by
> set LIB_SUFFIX, look like we have to set it specifically.

Ah, OK.

Still, graphite2, openjpeg, and qjson all install to $prefix/lib, even
when not passing CMAKE_INSTALL_LIBDIR=lib.  Is it really needed?

>>> if CMAKE_PREFIX_PATH not set to PATH of `inputs`, cmake will unable to
>>> find cmake modules of inputs.
>>
>> You’re talking about .cmake files, right?
> yes, but now I find out that they can under both lib/cmake and share/cmake.

In that case...

>> +      ;; Search path used by 'FIND_PACKAGE' and 'INCLUDE'.
>> +      (search-path-specification
>> +       (variable "CMAKE_MODULE_PATH")
>> +       (directories '("lib/cmake")))))
                                    ^
... just add "share/cmake" here. ---’

Could you try that?

> after add CMAKE_PREFIX_PATH with:
>
>   (search-path-specification
>     (variable "CMAKE_PREFIX_PATH")
>     (directories '("")))

I thought about it, but that "" is inelegant and not as clear.

> and here is the packages I'm working on:

Looks like a good start.  :-)

Thanks,
Ludo’.