[PATCH] D99018: [clang][flang] Moke the definition of `-module-dir` restricted to Flang

[Andrzej Warzynski via Phabricator via cfe-commits]

awarzynski added a subscriber: protze.joachim.
awarzynski added a comment.

Thank you for reviewing!

In D99018#2639680 <https://reviews.llvm.org/D99018#2639680>, @MaskRay wrote:

> Thanks. I do not know why `FlangOption and FC1 Options` needs be in `clang/include/clang/Driver/Options.td` but perhaps that is how things work:)

Options.td is where all options for `clangDriver` (the library) are defined. Since `flang` is implemented in terms of `clangDriver`, all options end up here. AFAIK,  there is no mechanism to have separate `Options.td` files for Flang and Clang. But since there is meant to be only one driver library in llvm-project, I think that this is fine. Instead, IMHO, we should aim for producing separate files for e.g. `clang -cc1` and `flang -fc1` (to have a clearer separation from the compiler and frontend drivers).

The extra flags: `FlangOption`, `FC1Option` and `FlangOnlyOption`, were added to enable _some_ filtering of the options. In particular, for making sure that `clang -help` doesn't contain any Flang-only options.

Btw, here's an RFC <https://lists.llvm.org/pipermail/cfe-dev/2020-October/066953.html> in which I discussed some of these issues.

CC @protze.joachim - this is somewhat related to what you brought up here: https://reviews.llvm.org/D95460.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D99018/new/

https://reviews.llvm.org/D99018