How to implement Make pattern rules in CMake?

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Hello, what would be the recommended approach in CMake to implement the so-called pattern rules as known in Make:

For example, the source files *.stub.php are used to generate the _arginfo.h files with PHP.

A follow up question:

  1. Would an unknown language extension in add_library(), add_executable() or target_sources() cause any issues in CMake somewhere?

For example:

add_library(foo)

target_sources(foo PRIVATE foo.c bar.c foo.stub.php)

Because, I was aiming a bit to add the CMakeDeterminePHPCompiler, CMakePHPInformation and other files to use enable_language(PHP) but the main issue is still figuring out proper dependency relations between the C objects in the linked library and the *.stub.php files. For example, the *_arginfo.h files from their accompanying *.stub.php files in the context of the library should be generated before compiling C files as they include the *_arginfo.h files.

I’m guessing that using CMakeDeterminePHPCompiler for generating files would be a bit of a cheating as there wouldn’t be any compilation here specifically, only generation.

And adding add_custom_command() gets a bit heavy IMHO in the build output phase and there comes an issue of retrieving the source files from either library source directory or the library target sources a bit.

Any suggestion is most welcome. Thank you.