fix: Add Homebrew Apple Silicon path detection in cmake finder modules#2474
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an-tao merged 2 commits intodrogonframework:masterfrom Mar 27, 2026
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On Apple Silicon Macs, Homebrew installs packages to /opt/homebrew instead of /usr/local (Intel Macs). The cmake finder modules were only searching Intel paths, causing build failures on Apple Silicon. This fix detects the Homebrew prefix dynamically using brew --prefix for each dependency, making builds work automatically on both Intel and Apple Silicon Macs without any manual cmake flags. Fixes drogonframework#2413
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Issue
On Apple Silicon Macs (M1/M2/M3), Homebrew installs packages to
/opt/homebrew/instead of/usr/local/which is where Intel Macs install them. The cmake finder modules were only searching the default paths which on Mac point to Intel Homebrew locations. This caused build failures on Apple Silicon with errors like:fatal error: 'json/json.h' file not found
Could NOT find BROTLI
This issue was reported in #2413 but was never resolved.
What I Found
While trying to build Drogon on a MacBook Air M3, I noticed the cmake finder modules in
cmake_modules/had no Apple Silicon path detection. The affected files were:FindJsoncpp.cmakeFindBrotli.cmakeFindSQLite3.cmakeFindHiredis.cmakeFindpg.cmakeI also looked into the history and found that PR #1345 tried to fix the Homebrew OpenSSL path but was closed after PR #1505 made OpenSSL optional. However the underlying cmake path problem for other dependencies was never addressed.
Fix
I added an
if(APPLE)block in each finder module that runsbrew --prefix <package>to dynamically detect the Homebrew installation path. This works automatically on both Intel and Apple Silicon Macs without requiring any manual cmake flags from the user.Testing
Tested on MacBook Air M3 running macOS with Apple Silicon.
Before this fix the build required manual flags:
cmake .. -DBUILD_EXAMPLES=ON -DCMAKE_PREFIX_PATH="/usr/local;/opt/homebrew" -DOPENSSL_ROOT_DIR=$(brew --prefix openssl)
After this fix it works with just:
cmake .. -DBUILD_EXAMPLES=ON
cmake output confirms automatic detection:
-- Found Jsoncpp: /opt/homebrew/opt/jsoncpp/include
-- Found Brotli: /opt/homebrew/opt/brotli/lib/libbrotlidec.dylib
Closes #2413
Note: clang-format was not applied as the changes are only in cmake finder modules, not C++ source files.