Fix pkgconfig file

[avalentino]

The curerrent implementation does not work on systems, like e.g. Debian, where the pkgconfig file is installed in
"/usr/lib/x86_64-linux-gnu/pkgconfig/blosc2.pc".

Since the current implementation assumes "prefix=${pcfiledir}/../.." (corretponding to "/user/lib" in this case), the path to include files ("includedir=${prefix}/include") results to be not correct.

The fix has been only tested on Debian.

[lshaw8317]

Hi, thanks for noticing this, and yes it is absolutely necessary to fix this. What do you think of this proposal?

prefix=@CMAKE_INSTALL_PREFIX@
exec_prefix=${prefix}
libdir=@CMAKE_INSTALL_FULL_LIBDIR@
includedir=@CMAKE_INSTALL_FULL_INCLUDEDIR@

[avalentino]

Not sure
I was not able to find any official documentation for CMAKE_INSTALL_FULL_INCLUDEDIR and CMAKE_INSTALL_FULL_LIBDIR.
Just a mention for the first one.

[avalentino]

What I put in my implementation exploits the same variable that are used in the install commands

[lshaw8317]

From https://cmake.org/cmake/help/latest/module/GNUInstallDirs.html:

CMAKE_INSTALL_FULL_<dir>
The absolute path generated from the corresponding CMAKE_INSTALL_<dir> value. If the value is not already an absolute path, an absolute path is constructed typically by prepending the value of the CMAKE_INSTALL_PREFIX variable, except in special cases as documented below.

These variables shouldn't be used in install() commands as they do not work with the cmake --install command's --prefix option, or with the cpack installer generators.

where <dir> is one of:

...

LIBDIR
object code libraries (lib or lib64)

On Debian, this may be lib/<multiarch-tuple> when CMAKE_INSTALL_PREFIX is /usr.

INCLUDEDIR
C header files (include)

[lshaw8317]

What I put in my implementation exploits the same variable that are used in the install commands

Ok, let's go with your solution then I think. It was what we had before I made the breaking change.

[avalentino]

From https://cmake.org/cmake/help/latest/module/GNUInstallDirs.html:

CMAKE_INSTALL_FULL_

The absolute path generated from the corresponding CMAKE_INSTALL_ value. If the value is not already an absolute path, an absolute path is constructed typically by prepending the value of the CMAKE_INSTALL_PREFIX variable, except in special cases as documented below.
These variables shouldn't be used in install() commands as they do not work with the cmake --install command's --prefix option, or with the cpack installer generators.
where is one of:
...
LIBDIR
object code libraries (lib or lib64)
On Debian, this may be lib/ when CMAKE_INSTALL_PREFIX is /usr.
INCLUDEDIR
C header files (include)

ah, sorry, I totally missed it
In that case I think that your solution in better

[lshaw8317]

I think the merged solution is fine, and reasonably robust. If in the future it causes problems we can revisit the discussion here I guess. Thanks very much!