[clang-tools-extra] [clangd] Expand response files before CDB interpolation (PR #75753)

[Dmitry Polukhin via cfe-commits]

https://github.com/dmpolukhin created https://github.com/llvm/llvm-project/pull/75753

Summary:

After https://reviews.llvm.org/D143436 response files stopped working with CDB interpolation. It has happened because interpolation removes all unknwn flags and extra input files. Response file is treated as an extra input because it is not a flag. Moreover inference needs full command line for driver mode and file type detection so all response files have to be expanded for correct inference.

This patch implements the simplest approach that add extra response file expansion before inference. Response file expansion in CommandMangler keep working for CDB pushed via LSP and will do nothing if all response files are already expanded.

Test Plan: TBD

Reviewers:

Subscribers:

Tasks: https://github.com/llvm/llvm-project/issues/69690

Tags:

>From 957951483dab19b0982a5dbe7d5370bd9061d931 Mon Sep 17 00:00:00 2001
From: Dmitry Polukhin <dmitry.polukhin at gmail.com>
Date: Sun, 17 Dec 2023 14:11:11 -0800
Subject: [PATCH] [clangd] Expand response files before CDB interpolation

Summary:

After https://reviews.llvm.org/D143436 response files stopped working
with CDB interpolation. It has happened because interpolation removes
all unknwn flags and extra input files. Response file is treated as an
extra input because it is not a flag. Moreover inference needs full
command line for driver mode and file type detection so all response
files have to be expanded for correct inference.

This patch implements the simplest approach that add extra response file
expansion before inference. Response file expansion in CommandMangler
keep working for CDB pushed via LSP and will do nothing if all response
files are already expanded.

Test Plan: TBD

Reviewers:

Subscribers:

Tasks: https://github.com/llvm/llvm-project/issues/69690

Tags:
---
 .../clangd/GlobalCompilationDatabase.cpp              | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/clang-tools-extra/clangd/GlobalCompilationDatabase.cpp b/clang-tools-extra/clangd/GlobalCompilationDatabase.cpp
index d1833759917a30..03ac1aa132d0bf 100644
--- a/clang-tools-extra/clangd/GlobalCompilationDatabase.cpp
+++ b/clang-tools-extra/clangd/GlobalCompilationDatabase.cpp
@@ -244,7 +244,16 @@ static std::unique_ptr<tooling::CompilationDatabase>
 parseJSON(PathRef Path, llvm::StringRef Data, std::string &Error) {
   if (auto CDB = tooling::JSONCompilationDatabase::loadFromBuffer(
           Data, Error, tooling::JSONCommandLineSyntax::AutoDetect)) {
-    return tooling::inferMissingCompileCommands(std::move(CDB));
+    // FS used for expanding response files.
+    // FIXME: ExpandResponseFilesDatabase appears not to provide the usual
+    // thread-safety guarantees, as the access to FS is not locked!
+    // For now, use the real FS, which is known to be threadsafe (if we don't
+    // use/change working directory, which ExpandResponseFilesDatabase doesn't).
+    // NOTE: response files have to be expanded before inference because inference
+    // needs full command line to check/fix driver mode and file type.
+    auto FS = llvm::vfs::getRealFileSystem();
+    return tooling::inferMissingCompileCommands(
+            expandResponseFiles(std::move(CDB), std::move(FS)));
   }
   return nullptr;
 }