Install headers in a suitesparse subdirectory?

[mmuetzel]

Motivated by build failures on macOS if old versions of SuiteSparse from Homebrew are installed when building SuiteSparse.
Copying a comment from another thread to avoid loosing this:

@DrTimothyAldenDavis: We can't do anything about older versions. But could the headers of the SuiteSparse libraries be installed in a sub-directory (e.g., /usr/local/include/suitesparse)?
Currently, there is the risk of headers from older libraries being picked up when the include path (e.g., /usr/local/include) gets added for other dependencies installed on the build system (e.g., OpenMP). That risk would be lower if the headers were installed in their own directory. CMake targets and pkg-config files would help dependent projects to find the correct folder with the headers.

Probably not something that should be changed for the current beta (or ever). But maybe for a later release?

[DrTimothyAldenDavis]

That would just delay the problem.

The cmake build system knows where all the latest files are; if it's building AMD, let's say, then it knows that the correct SuiteSparse_config.h is in ../SuiteSparse_config/SuiteSparse_config.h.

Directories scanned with -I take precedence over system directories, right? So we just need to make sure -ISuiteSparse_config/Include (for example) appears in all packages that use SuiteSparse_config. Doesn't that always happen?

[mmuetzel]

Directories scanned with -I take precedence over system directories, right? So we just need to make sure -ISuiteSparse_config/Include (for example) appears in all packages that use SuiteSparse_config. Doesn't that always happen?

Those flags should be added for all libraries that use SuiteSparse_config currently. But they might be appearing after the -I flag for the other folder if the dependency for OpenMP is added earlier...

If the SuiteSparse headers hadn't been present in a folder that is shared with other (system) libraries, the order of the -I flags wouldn't matter.

We can try and control the order of the -I flags when building SuiteSparse. But if multiple versions of the headers are installed in different directories (like for @Fabian188) other projects that depend on SuiteSparse libraries could still get the wrong order of -I flags.
If the headers are at a location that isn't shared with other libraries, we could make sure that the order doesn't matter. (That is at least when the SuiteSparse headers disappeared from directories that are shared with the headers of other libraries.)

[mmuetzel]

See #568 for a potential change that would move the headers of (most of) the SuiteSparse headers to their dedicated directory where they can't be confused when headers from other libraries need that a common directory is added to the preprocessor search path.

[DrTimothyAldenDavis]

This is working well so I'll stick with this: all the headers get installed by default into /usr/local/include/suitesparse.

[mmuetzel]

To clarify: Only the headers of projects that use SUITESPARSE_INCLUDEDIR are installed in a include/suitesparse subdirectory.
GraphBLAS and LAGraph don't use that CMake variable (for compatibility with the upstream projects?) and their headers are installed directly in the include directory.

Please, let me know if they should also use the SUITESPARSE_*DIR variables and I can take a look at it...

[mmuetzel]

Oops. They do...

I wonder why they don't install in the correct location then. Maybe, the SuiteSparsePolicy files got out of sync?

Edit: They install in include/suitesparse with the root CMakeLists.txt. But they install in include with the root Makefile.
So, it's most likely caused by different SuiteSparsePolicy modules...

[DrTimothyAldenDavis]

I just saw that a few hours ago that and updated them so each of the 3 Policy .cmake files are now the same.

Just now I saw your note about that so we might have both seen it and crossed in the ether.

I think it should be fixed now.

[DrTimothyAldenDavis]

I know it's a bit odd to have LAGraph depend on SuitesparsePolicy.cmake, since LAGraph is meant to be a stand alone library that can use other GraphBLAS library implementations.

But if it's integrated into SuiteSparse then I think that's ok.

[Fabian188]

This is working well so I'll stick with this: all the headers get installed by default into /usr/local/include/suitesparse.

How is this controlled? CMAKE_INSTALL_PREFIX/include/suitesparse ?

[DrTimothyAldenDavis]

That's the default if you do nothing. But you can also set

SUITESPARSE_INCLUDEDIR_POSTFIX
which defaults to suitesparse

The folder is CMAKE_INSTALL_PREFIX/include/SUITESPARSE_INCLUDEDIR_POSTFIX

so if you want to install directly into /usr/local/include, just set the SUITESPARSE_INCLUDEDIR_POSTFIX to the empty string.

[DrTimothyAldenDavis]

This is now fixed in SuiteSparse 7.4.0.beta1.