Fix Xcode PCH redefinition warnings for clang's libc++ hardening mode#1076
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SRSaunders wants to merge 3 commits intoRobertBeckebans:masterfrom
Open
Fix Xcode PCH redefinition warnings for clang's libc++ hardening mode#1076SRSaunders wants to merge 3 commits intoRobertBeckebans:masterfrom
SRSaunders wants to merge 3 commits intoRobertBeckebans:masterfrom
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This fixes #1075 for llvm's libc++ hardening mode starting with llvm 18.
Although the fix is designed to avoid PCH redefinition errors on Apple Xcode builds with AppleClang 17+, the solution is general in that other platforms and build types can take advantage of the improvement.
The solution defines new
CLANG_CXX_FLAGS_<build-type>cmake variables (default empty) that are appended to the existingCMAKE_CXX_FLAGS_<build-type>variables and passed to both PCH and regular build components. For Xcode builds using AppleClang 17+ (containing llvm 19+), these new variables are automatically set to match Xcode's defaults for the hardening defines. However, they can be manually set on any build type or platform for non-MSVC compilers.For example, a linux (or macOS) release build could add the following to their
cmake-<platform>-release.shscript to enable_LIBCPP_HARDENING_MODE_FAST:-DCLANG_CXX_FLAGS_RELEASE="-U_LIBCPP_HARDENING_MODE -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_FAST"This PR also fixes a small PCH cleanup issue for rbdmap when using non-MSVC IDE builds (tested with Xcode).
Tested on macOS Sequoia with Xcode 26.2 builds as well as command line builds (debug and release variants). Also tested on Linux Manjaro + clang 21 with
_LIBCPP_HARDENING_MODE_FASToverride on command line release build.