A Gtk4 CMakeLists.txt example that includes gmodule-export-2.0

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I don’t believe that’s related to the sort of exports that gmodule is looking for, and regardless it’s unnecessary because…

And because that’s a requirement, it’s encoded into the pkg-config data for the library:

$ pkg-config --cflags --libs gmodule-export-2.0 |fmt
-I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include
-I/usr/include/sysprof-6 -pthread -Wl,--export-dynamic -lgmodule-2.0
-pthread -lglib-2.0

So if you get the pkg_check_modules stuff right, it’ll be taken care of automatically.

A couple of observations:

  1. While it’s not wrong to set up each pkg-config dependency separately, if they’re all targeted to the same executable/library, you can also do them all at once for convenience — it’s called pkg_check_moduleS(), plural.
  2. I’d suggest raising your cmake_minimum_required() version to the still-ancient 3.7, and telling FindPkgConfig to create a target with the pkg-config dependencies, so that you can consume all of its results with a simple target_link_libraries() call.

So, something like this should work:

cmake_minimum_required(3.7 .. 3.30)

find_package(PkgConfig REQUIRED)

pkg_check_modules(
  Dependencies REQUIRED
  IMPORTED_TARGET 
  gtk4>=4.16.5 
  libadwaita-1>=1.6.1 
  gmodule-export-2.0>=2.82.2
)

FindPkgConfig will create a target named PkgConfig::Dependencies with all of the CFLAGS, linker args, and etc. set up on it, which you can use on your executable:

add_executable(DrogonCMS ${SOURCES})

# ...after all of the dependency-finding...

target_link_libraries(
  DrogonCMS PRIVATE
  PkgConfig::Dependencies
)

…that replaces all of the ${[GTK4|ADW|GMODULE-EXPORTS-2.0]_INCLUDE_DIRS}, ${..._LIBRARY_DIRS}, ${... CFLAGS_OTHER}, etc. you were consuming.

Note that you’ll still have to set up the other dependencies on your executable target, though I’d suggest doing that with the targeted (no pun) commands instead:

target_include_directories(
  DrogonCMS PRIVATE
    ${PostgreSQL_INCLUDE_DIRS}
    # etc...
)

…Or, better yet, if you up your cmake_minimum_required() version a bit farther to CMake 3.14 (which is still pretty old), FindPostgreSQL will create an IMPORTED target just like pkg-config. So then you just do,

find_package (PostgreSQL)
if (TARGET PostgreSQL::PostgreSQL)
  target_link_libraries(DrogonCMS PRIVATE
    PostgreSQL::PostgreSQL
  )
else()
  pkg_check_modules(
    Sqlite3 REQUIRED
    IMPORTED_TARGET
    sqlite3>=3.43.1
  )
  # Not technically necessary because the
  # REQUIRED would cause pkg_check_modules
  # to fail if it couldn't create it, but...
  if(TARGET PkgConfig::Sqlite3)
    target_link_libraries(DrogonCMS PRIVATE
      PkgConfig::Sqlite3
    )
  endif()
endif()

…Oh, and as a final style note (you’re clearly working from some very old CMakeLists.txt files as examples)… the endif (<repeat_the_if_conditions>) style is long deprecated. Just use endif (). Same thing for endforeach(), endfunction(), etc.

I’d recommend giving An Introduction to Modern CMake a read, and unlearning all of the bad old habits demonstrated by those ancient, ancient CMakeLists.txt files.

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