[PATCH] D108366: [clang][deps] Deduce resource directory from the compiler path

[Jan Svoboda via Phabricator via cfe-commits]

jansvoboda11 added a comment.

Tagging @kousikk, since this is related to D69122 <https://reviews.llvm.org/D69122> that introduced `ResourceDirectoryCache` to `clang-scan-deps`. When the compilation command doesn't have a `-resource-dir` argument, `ResourceDirectoryCache` invokes the specified compiler with `-print-resource-dir` and injects the result into the command-line as `-resource-dir`.

This happens way before the dependency scanner worker is invoked, meaning the logic this patch tweaks won't usually kick in. The test passes only because the invocation of `/our/custom/bin/clang -print-resource-dir` made by `ResourceDirectoryCache` silently fails (the binary doesn't exist), allowing the worker to deduce the resource directory using regular driver logic.

I think both `clang-scan-deps` and the downstream libclang API clearly head towards only supporting compilers built the same way (same version, architecture, etc.). The modular dependency scanner already returns command-lines of cc1 arguments that are not stable across Clang versions.

I wanted to see if we can reach consensus on removing `ResourceDirectoryCache` entirely. It makes the resource directory deduction much more lightweight and is in line with the direction we're already going regarding compiler compatibility. It also allows `clang-scan-deps` and libclang API to have the same behavior, which is a desirable property IMO. If users really want the behavior of `ResourceDirectoryCache`, they can keep using prior versions `clang-scan-deps`.

What do you all think?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D108366/new/

https://reviews.llvm.org/D108366