There a many flags which are applied globally across the compilations. These flags probably mostly exist in the SCosntruct. These flags should be searched in the SConstructs/SConscripts and if the flag is added under usual circumstances (our v4 toolchain and no specific options), then it should be brought into bazel, probably added in our mongo_* macros. The raw list of flags to investigate is below:
-Woverloaded-virtual
-Wpessimizing-move
-Wno-maybe-uninitialized
-fsized-deallocation
-Werror
-ffp-contract=off
-fasynchronous-unwind-tables
-g2
-Wall
-Wsign-compare
-Wno-unknown-pragmas
-Winvalid-pch
-gdwarf-5
-fno-omit-frame-pointer
-fno-strict-aliasing
-march=armv8.2-a
-mtune=generic
-Wno-unused-local-typedefs
-Wno-unused-function
-Wno-deprecated-declarations
-Wno-unused-const-variable
-Wno-unused-but-set-variable
-Wno-missing-braces
-Wno-psabi
-fstack-protector-strong
-gdwarf64
Wa,-nocompress-debug-sections
-Wimplicit-fallthrough=5
-fPIE
-DSAFEINT_USE_INTRINSICS=0
-DPCRE2_STATIC
-DNDEBUG
-D_XOPEN_SOURCE=700
-D_GNU_SOURCE
-D_FORTIFY_SOURCE=2
-DABSL_FORCE_ALIGNED_ACCESS
-DBOOST_ENABLE_ASSERT_DEBUG_HANDLER
-DBOOST_FILESYSTEM_NO_CXX20_ATOMIC_REF
-DBOOST_LOG_NO_SHORTHAND_NAMES
-DBOOST_LOG_USE_NATIVE_SYSLOG
-DBOOST_LOG_WITHOUT_THREAD_ATTR
-DBOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
-DBOOST_SYSTEM_NO_DEPRECATED
-DBOOST_THREAD_USES_DATETIME
-DBOOST_THREAD_VERSION=5