awarzynski added a comment. In D105881#2919575 <https://reviews.llvm.org/D105881#2919575>, @jansvoboda11 wrote:
> The `clang` driver always accepts both the positive and negative options, and > it always only considers the argument that appeared last on the command-line > (using `ArgList::getLastArg(Pos, Neg)`). This allows users to take a random > `clang` driver command-line, append `-feliminate-unused-debug-types` and get > the desired behavior, even though the original command-line might have > contained `-fno-eliminate-unused-debug-types`. > > For the pair of options you mentioned, the `clang` driver knows they are > "opt-out" in `clang -cc1`. The behavior is enabled by default in `-cc1` and > can be disabled/opted-out through the negative > `-fno-eliminate-unused-debug-types`. The positive option is **not** accepted > by `clang -cc1`, since explicitly enabling a behavior that's already enabled > by default is redundant. > > If driver sees `-fno-eliminate-unused-debug-types` as the last option, it > will forward it to `clang -cc1`. If it sees `-feliminate-unused-debug-types`, > it will ignore it. > > Does this make sense? Yes. Thanks for the context and the rationale! This is much clearer now and indeed, makes sense. It's hard to extract this stuff from `Options.td` so I really appreciate you taking the time to explain it. > The `HelpText` doesn't play a role in option being accepted or not in `clang` > or `clang -cc1`. We are 100% in agreement with regard to `HelpText`. > I think we're in agreement that the current distinction between > `HelpText<"">` and no `HelpText` is not particularly useful when printing > help. Yes. Updating printHelp <https://github.com/llvm/llvm-project/blob/main/llvm/lib/Option/OptTable.cpp#L575> wouldn't be too difficult. Would you be in favor? > I agree we shouldn't mix Clang and Flang options together in `-help`. But to > make sure we're on the same page: this doesn't have to do anything with the > presence/absence of `HelpText`, this is controlled by `FlangOption`, > `FC1Option`, `CC1Option` etc. Agreed. I've experimented with a few more approaches and feel that the cleanest approach would be to: - rename `OptOutFFlag`/`OptInFFlag` as `OptOutCC1FFlag` and `OptInCC1FFlag` - introduce `OptOutFC1FFlag` and `OptInFC1FFlag`. We will end-up with a bit of duplication in Options.td, but the long term goal is to split it into multiple files anyway. Also, I think that in this case code re-use would lead to a rather convoluted implementation. I'm will send an updated patch shortly. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D105881/new/ https://reviews.llvm.org/D105881 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
