ldionne wrote:
This is really tricky, however I believe the current behavior is correct (and
in fact it's the only correct way of handling this). The
`{LIBCXX,LIBCXXABI,LIBUNWIND}_ADDITIONAL_COMPILE_FLAGS` options expect to be
passed something that is already formatted as a CMake list with `;` to delimit
separate arguments. This is necessary to prevent CMake from incorrectly
deduplicating some flags.
For example, after your patch, passing
`-DLIBCXX_ADDITIONAL_COMPILE_FLAGS="-Xclang -pedantic -Xclang
-disable-llvm-passes"` when configuring with CMake would fail, because that
would be split into the list `-Xclang;-pedantic;-Xclang;-disable-llvm-passes`,
which CMake will deduplicate to `-Xclang;-pedantic;-disable-llvm-passes` and
pass to the compiler as `-Xclang -pedantic -disable-llvm-passes`, which is
invalid. Getting this right is very tricky. CMake option-deduplication is
documented
[here](https://cmake.org/cmake/help/v3.30/command/add_compile_options.html#option-de-duplication).
The right way to pass such arguments is to use `SHELL:` to tell Clang that it
should group arguments and then separate them before passing them to the
compiler. So you end up passing
`-DLIBCXX_ADDITIONAL_COMPILE_FLAGS="-v;-O3;SHELL:-Xclang -pedantic;-Xclang
-disable-llvm-passes"` to CMake, which will then pass `-v -O3 -Xclang -pedantic
-Xclang -disable-llvm-passes` to the compiler. Alternatively, I think you can
also just pass a single `SHELL` argument like
`-DLIBCXX_ADDITIONAL_COMPILE_FLAGS="SHELL:-v -O3 -Xclang -pedantic -Xclang
-disable-llvm-passes"` -- in that case you'd be passing a 1-element list of
compile flags, which is comprised of the `-v -O3 -Xclang -pedantic -Xclang
-disable-llvm-passes` "option-group".
https://github.com/llvm/llvm-project/pull/112703
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
