t8_config.h missing from cmake install manifest

[ackirby88]

Bug report

For the cmake build and install, t8_config.h is missing from the install manifest, which causes the following error:

t8code/include/t8.h:34:10: fatal error: t8_config.h: No such file or directory
   34 | #include <t8_config.h>

Estimated priority
Priority: high

Additional context
To fix, simply add "t8_config.h" to src/CMakeLists.txt install FILES section (line ~178).

[Davknapp]

Hello @ackirby88 ,

thank you for you Issue. t8_config.h is a file that is produced by the autotools build-system and therefore should only exists if you are using the autotools system. Have you recently updated to the CMake buildsystem? I tried to reproduce error by linking our png2mesh project with an installation of t8code and was unable to reproduce the error. Did you switch the build-system recently? Maybe it helps to ensure that there are no files used by the old build system in your installation/build-directory.

I hope that this helps you already.

[lukasdreyer]

Hi @ackirby88,

I might have stumbled upon the same thing recently: cburstedde/libsc#206 (comment)

Do you add t8code by a find_package(T8CODE CONFIG) call?
The error that you run into is because T8_CMAKE_BUILD is not set. It should come from the T8CODE-targets.cmake file.

The error that I ran into recently was because of some of the generators in SC-targets.cmake and p4est-targets.cmake not being evaluated correctly.
Can you check if these two files in your cmake folder in the installed t8code have some lines containing <$<0 or <$<1 in the INTERFACE_LINK_LIBRARIES in set_target_properties?
If so, please check if removing the 0 entries and shortening the 1 entries solves your problem.

You might also need to set all of T8CODE_DIR, P4EST_DIR and SC_DIR to your cmake directory in the installed t8_version.

We are also thinking about providing a t8_config.h with the cmake build, but we have not yet figured out the details.

I am also very interested in your experience in fixing this issue, as we are trying to further improve our cmake build system.

[Davknapp]

Might be solved by: cburstedde/libsc#212

[ackirby88]

It looks like it should be fine, since there is an explicit target_compile_definitions( T8 PUBLIC T8_CMAKE_BUILD ) in the CMakeLists.txt on the top level, which should prevent it from being included in the t8.h file via

#ifndef T8_CMAKE_BUILD
#include <t8_config.h>
#endif

I probably have some old autoconf configuration stuff lying around in the same directory causing issues (did a git pull on a submodule).

I'll close the issue assuming that there isn't an actual bug, but reopen it if I do find an actual problem. Apologies for causing a stir!

[ackirby88]

Ah! So you need to fix the CMakeLists.txt file by adding "-D":

target_compile_definitions( T8 PUBLIC -DT8_CMAKE_BUILD )

[Davknapp]

Thank you for your suggestion!