Unable to point to a static, offline copy of dependencies

[bwarden]

In order to package this software for a distribution, or any software that requires it as part of its own build (such as DPC++ Compiler), it is essential that all necessary source code can be downloaded and provided offline, such that the build will not attempt to retrieve anything from the internet.

unified-runtime/cmake/FetchLevelZero.cmake

Lines 112 to 124 in 6b5dec6

	# Sparse fetch only the dir with level zero headers for experimental features to avoid pulling in the entire compute-runtime.
	FetchContentSparse_Declare(exp-headers ${UR_COMPUTE_RUNTIME_REPO} "${UR_COMPUTE_RUNTIME_TAG}" "level_zero/include")
	FetchContent_GetProperties(exp-headers)
	if(NOT exp-headers_POPULATED)
	FetchContent_Populate(exp-headers)
	endif()
	add_library(ComputeRuntimeLevelZero-Headers INTERFACE)
	set(COMPUTE_RUNTIME_LEVEL_ZERO_INCLUDE "${exp-headers_SOURCE_DIR}/../..")
	message(STATUS "Level Zero Adapter: Using Level Zero headers from ${COMPUTE_RUNTIME_LEVEL_ZERO_INCLUDE}")
	target_include_directories(ComputeRuntimeLevelZero-Headers
	INTERFACE "$<BUILD_INTERFACE:${COMPUTE_RUNTIME_LEVEL_ZERO_INCLUDE}>"
	"$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>"
	)

Ideally, cmake's own methods such as find_package should be used, but lacking that, I should be able to provide variables that point to wherever I have unpacked compute-runtime.

[alycm]

Note this is the same use-case, but with different suggestions, as #2494.