Move handling of Cocoa option after FreeType

[vepadulano]

When building on Apple with Cocoa graphics, FreeType is required. Previously, there were two separate ways to check for FreeType availability:

• The "standard" checks for builtins, forcing availability when fail-on-missing is ON, otherwise falling back to activating the builtin if the external package is not found
• An injected check in the section related to Cocoa, which happened before the section for the builtin, which practically meant that on Apple with Cocoa enabled ROOT was always built with the builtin FreeType library.

This commit proposes to move the section related to Cocoa after the section related to FreeType. This way, the build on Cocoa can only:

• Fail if FreeType is not found, when fail-on-missing is ON
• Use the FreeType seen by the rest of the build, the result of the checks in the FreeType section.

As a result, MacOS builds can also now use an externally provided FreeType, useful e.g. for conda-forge builds.

This commit removes the need for the following conda-forge patch: https://github.com/conda-forge/root-feedstock/blob/df86316b299d8214d3181d76c31925696f076d5e/recipe/patches/0009-disable-builtin-freetype-macos.patch

[github-actions]

Test Results

    22 files      22 suites   3d 2h 57m 33s ⏱️
 3 804 tests  3 801 ✅ 1 💤 2 ❌
75 649 runs  75 638 ✅ 9 💤 2 ❌

For more details on these failures, see this check.

Results for commit 76b795c.

♻️ This comment has been updated with latest results.

[guitargeek]

Great! This change actually shows that the fail-on-missing mechanism was not implemented for the builtin_freetype. Can you maybe add it in this PR, copying some code for other builtins? The idea is that no builtin is implicitly enabled if you set fail-on-missin=ON. The configuration should fail then with an error that tells you which builtin you have to enable.

[vepadulano]

Great! This change actually shows that the fail-on-missing mechanism was not implemented for the builtin_freetype. Can you maybe add it in this PR, copying some code for other builtins? The idea is that no builtin is implicitly enabled if you set fail-on-missin=ON. The configuration should fail then with an error that tells you which builtin you have to enable.

Actually it's even trickier than that! The logic for fail-on-missing for builtin_freetype is implemented at

root/cmake/modules/SearchInstalledSoftware.cmake

Lines 206 to 219 in 517a231

	if(NOT builtin_freetype)
	message(STATUS "Looking for Freetype")
	if(fail-on-missing)
	find_package(Freetype REQUIRED)
	else()
	find_package(Freetype)
	if(FREETYPE_FOUND)
	set(FREETYPE_INCLUDE_DIR ${FREETYPE_INCLUDE_DIR_freetype2})
	else()
	message(STATUS "FreeType not found. Switching on builtin_freetype option")
	set(builtin_freetype ON CACHE BOOL "Enabled because FreeType not found (${builtin_freetype_description})" FORCE)
	endif()
	endif()
	endif()

. But then this part of the CMake code completely bypasses that and injects the builtin because it's needed on Apple with Cocoa graphics.

[guitargeek]

Thank you very much for this!