Fix finding LLD on Homebrew when multiple versions are installed. #8619
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LLVM sadly doesn't provide *ConfigVersion.cmake files for its sub-components, including Clang and LLD. Consequently, attempting to constrain the version to LLVM_PACKAGE_VERSION prevents these find_package calls from succeeding at all. Worse, package maintainers have some "interesting" ideas as to how they should lay out the -dev packages, especially when they want to support multiple parallel versions. These hints take effect at a lower precedence than Halide_LLVM_ROOT or CMAKE_PREFIX_PATH (which are the standard ways of setting up the dependency search), but at a higher precedence than the system-wide fallback locations. In particular, Homebrew split the LLVM and LLD packages as of version 19, so having multiple LLVM versions installed leads to the newest LLD being found without the hint in this commit.
abadams
approved these changes
Apr 23, 2025
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Failures are due to buildbot issues: missing Node environment and some corrupt PCH. |
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LLVM sadly doesn't provide *ConfigVersion.cmake files for its sub-components, including Clang and LLD. Consequently, attempting to constrain the version to
LLVM_PACKAGE_VERSIONprevents these find_package calls from succeeding at all. Worse, package maintainers have some "interesting" ideas as to how they should lay out the-devpackages, especially when they want to support multiple parallel versions. These hints take effect at a lower precedence thanHalide_LLVM_ROOTorCMAKE_PREFIX_PATH(which are the standard ways of setting up the dependency search), but at a higher precedence than the system-wide fallback locations.In particular, Homebrew split the LLVM and LLD packages as of version 19, so having multiple LLVM versions installed leads to the newest LLD being found without the hint in this commit.