Build fails: fallthrough annotation does not directly precede switch label

[yurivict]

FAILED: proxygen/lib/CMakeFiles/proxygen.dir/__/__/generated/proxygen/lib/http/HTTPCommonHeaders.cpp.o 
/usr/bin/c++ -DFMT_SHARED -DGFLAGS_IS_A_DLL=0 -Dproxygen_EXPORTS -I/wrkdirs/usr/ports/www/proxygen/work/proxygen-2025.05.05.00 -I/wrkdirs/usr/ports/www/proxygen/work/.build/generated -isystem /usr/local/include -O2 -pipe -fstack-protector-strong -fno-strict-aliasing  -fPIC -DGLOG_USE_GLOG_EXPORT -O2 -pipe -fstack-protector-strong -fno-strict-aliasing  -fPIC -DGLOG_USE_GLOG_EXPORT  -DNDEBUG -std=c++17 -fPIC -Wall -Wextra -Wno-noexcept-type -Wno-unused-parameter -Wno-missing-field-initializers -Wno-nullability-completeness -Wno-deprecated-register -Wno-register -Wno-unused-value -pthread -MD -MT proxygen/lib/CMakeFiles/proxygen.dir/__/__/generated/proxygen/lib/http/HTTPCommonHeaders.cpp.o -MF proxygen/lib/CMakeFiles/proxygen.dir/__/__/generated/proxygen/lib/http/HTTPCommonHeaders.cpp.o.d -o proxygen/lib/CMakeFiles/proxygen.dir/__/__/generated/proxygen/lib/http/HTTPCommonHeaders.cpp.o -c /wrkdirs/usr/ports/www/proxygen/work/.build/generated/proxygen/lib/http/HTTPCommonHeaders.cpp
/wrkdirs/usr/ports/www/proxygen/work/.build/generated/proxygen/lib/http/HTTPCommonHeaders.cpp:150:7: error: fallthrough annotation does not directly precede switch label
  150 |       [[fallthrough]];
      |       ^
/wrkdirs/usr/ports/www/proxygen/work/.build/generated/proxygen/lib/http/HTTPCommonHeaders.cpp:176:7: error: fallthrough annotation does not directly precede switch label
  176 |       [[fallthrough]];
      |       ^
2 errors generated.
ninja: build stopped: subcommand failed.
*** Error code 1

log

Version: 2025.05.05.00
clang-19
FreeBSD 14.2

[afrind]

Yes, we saw this started failing and are working on a solution. See #558 for a potential solution, though it doesn't pass all our internal tests yet.