[PATCH] D124432: Fix issues with using clangd with C++ modules

[Kugan Vivekanandarajah via Phabricator via cfe-commits]

kuganv created this revision.
Herald added subscribers: dexonsmith, usaxena95, kadircet, arphaman.
Herald added a project: All.
kuganv requested review of this revision.
Herald added subscribers: cfe-commits, MaskRay, ilya-biryukov.
Herald added projects: clang, clang-tools-extra.

Fixes following incompatibility issues with c++ modules
(clangd with c++ modules results in assertion failure and pch_langopt_mismatch #1105)

1. Preamble generated by clangd is generated with WriteCommentListToPCH = false;

However, if we are using precompiled modules that have comments in the
serialised AST, following sanity check in the clangd fails.

// Sanity check that the comment does not come from the PCH. We choose to not
// write them into PCH, because they are racy and slow to load.
assert(!Ctx.getSourceManager().isLoadedSourceLocation(RC→getBeginLoc()));

In this patch when we are generating Preamble with
WriteCommentListToPCH, we do not load the comments from AST.

2. If we have modules that are built with RetainCommentsFromSystemHeaders

difference, that would prevent modules from getting loaded. Since this
difference is not critical that should be stopping modules from being loaded,
this patch changes it to be a COMPATIBLE_LANGOPT.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D124432

Files:
  clang-tools-extra/clangd/test/modules-options-compatablity-test/A.h
  clang-tools-extra/clangd/test/modules-options-compatablity-test/B.h
  clang-tools-extra/clangd/test/modules-options-compatablity-test/compile_commands.json
  clang-tools-extra/clangd/test/modules-options-compatablity-test/definition.jsonrpc
  clang-tools-extra/clangd/test/modules-options-compatablity-test/module.modulemap
  clang-tools-extra/clangd/test/modules-options-compatablity-test/use.c
  clang-tools-extra/clangd/test/modules-options-compatablity.test
  clang/include/clang/Basic/LangOptions.def
  clang/lib/Serialization/ASTReader.cpp

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