Add SlangConfig.cmake with slang build targets

[ov-l]

Closes #5649

[CLAassistant]

All committers have signed the CLA.

[ov-l]

I need to reformat the CMakeLists file.

[obhi-d]

I am not able to make the wasm build work, so probably I need to skip adding slang as target. I tried to add through this macro:

macro(export_slang_targets)
  set(SlangExportTargetList)
  foreach(target IN ITEMS ${ARGN})
    message(STATUS "----------------> ADDING TARGET ${target}")
    if(TARGET ${target})
      list(APPEND SlangExportTargetList ${target})
    endif()
  endforeach()
  
  if (SlangExportTargetList)
  
    install(TARGETS ${SlangExportTargetList} EXPORT SlangExportTarget)
    
    install(
        EXPORT SlangExportTarget
        FILE ${PROJECT_NAME}Targets.cmake
        NAMESPACE ${PROJECT_NAME}::
        DESTINATION cmake
    )
    
    install(
        FILES
            "${PROJECT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"
            "${PROJECT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"
        DESTINATION cmake
    )
  
  endif()
endmacro()

# 
export_slang_targets(
  core
  prelude
  unordered_dense
  compiler-core
  slang-capability-defs
  slang-capability-lookup
  slang-reflect-headers
  slang-lookup-tables
  SPIRV-Headers
  slang-common-objects
  slang
)

But other issues crop up if I do so, notably : Target "slang-reflect-headers" INTERFACE_INCLUDE_DIRECTORIES property
contains path: , which is prefixed in the build directory.

Exporting all targets specified in SlangTargets is also not an option because it seems SlangTargets include every target declared within the library and they should not be linked to (for ex. executable targets).

For my use-case, only single slang target works for both Linux and Windows. Probably this needs to be handled correctly instead of how I am doing.

[eliemichel]

It might be ok to just not try to find a prebuilt version of Slang when cross-compiling with emscripten (i.e., enclose the find_package within a if (NOT EMSCRIPTEN) and fallback to "manually" locating slangc executable in that case (because I suppose that's all what is needed when the target is WebAssembly -- unless one wants to link slang library into a WebAssembly module but there is no precompiled release for WebAssembly anyways, so one would build from scratch in that case).

[obhi-d]

It might be ok to just not try to find a prebuilt version of Slang when cross-compiling with emscripten (i.e., enclose the find_package within a if (NOT EMSCRIPTEN) and fallback to "manually" locating slangc executable in that case (because I suppose that's all what is needed when the target is WebAssembly -- unless one wants to link slang library into a WebAssembly module but there is no precompiled release for WebAssembly anyways, so one would build from scratch in that case).

Yes, I missed your point earlier. I will try that. Thanks for clarifying.