Fix handling of libyaml in CMake build

[dougiesquire]

Description

In the CMake build, when using WITH_YAML:

• if a kind is specified, no linking is done against libyaml
• if a kind is not specified, the following is done:

  target_link_libraries(${libTgt}_c PRIVATE libyaml_C)
  set_target_properties(${libTgt}_c PROPERTIES COMPILE_FLAGS "-L${LIBYAML_LIBRARIES} -lyaml")

  But, I think the final FMS library (${libTgt}) just copies the object files and the link dependencies are not propagated anyway:

  add_library(${libTgt} STATIC $<TARGET_OBJECTS:${libTgt}_c>
                               $<TARGET_OBJECTS:${libTgt}_f>)

Thus, though the FMS library compiles, when I try to build an executable, I see:

  >> 172    yaml_output_functions.c:(.text+0x54): undefined reference to `yaml_scalar_event_initialize'
  >> 173    yaml_output_functions.c:(.text+0x63): undefined reference to `yaml_emitter_emit'
  ...

This PR tries to fix this by:

• Linking ${libTgt}, rather than ${libTgt}_c, against libyaml
• Adding libyaml as a dependency to FMSConfig.cmake
• Installing Findlibyaml.cmake alongside the exported configuration UPDATE: libyaml is now found using pkg-config so Findlibyaml.cmake has been removed.

How Has This Been Tested?
With these changes I am able to install our ocean model with FMS yaml support, where previously I wasn't.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included
• make distcheck passes

[dougiesquire]

Note, we could also get rid of Findlibyaml.cmake and use pkg-config to handle the dependency, but note that the .pc file for libyaml is strangely named yaml-0.1.pc:

-  find_package(libyaml REQUIRED)
+  find_package(PkgConfig REQUIRED)
+  pkg_check_modules(YAML REQUIRED IMPORTED_TARGET "yaml-0.1")

[rem1776]

LGTM!

[rem1776]

Note, we could also get rid of Findlibyaml.cmake and use pkg-config to handle the dependency, but note that the .pc file for libyaml is strangely named yaml-0.1.pc:

-  find_package(libyaml REQUIRED)
+  find_package(PkgConfig REQUIRED)
+  pkg_check_modules(YAML REQUIRED IMPORTED_TARGET "yaml-0.1")

No issues here with using pkg-config instead if you would like to include that change.

[dougiesquire]

No issues here with using pkg-config instead if you would like to include that change.

Thanks @rem1776. Done in b57d653.

[rem1776]

Looks good and works on my system but is failing in our CI testing. I'll take a look and try to get it passing as it should, its probably from the github workflow messing with the shell.

[uramirez8707]

Thank you for fixing this.