[clang] [clang][deps] Fix dependency scanning with -working-directory (PR #84525)

[Ben Langmuir via cfe-commits]

https://github.com/benlangmuir created https://github.com/llvm/llvm-project/pull/84525

Stop overriding -working-directory to CWD during argument parsing, which should no longer necessary after we set the VFS working directory, and set FSOpts correctly after parsing arguments so that working-directory behaves correctly.

>From e214b51d85fd203a6ec8be3d5aef6b3aa3d8d741 Mon Sep 17 00:00:00 2001
From: Ben Langmuir <blangmuir at apple.com>
Date: Fri, 8 Mar 2024 09:53:42 -0800
Subject: [PATCH] [clang][deps] Fix dependency scanning with -working-directory

Stop overriding -working-directory to CWD during argument parsing, which
should no longer necessary after we set the VFS working directory, and
set FSOpts correctly after parsing arguments so that working-directory
behaves correctly.
---
 .../DependencyScanningWorker.cpp              |  8 +++--
 .../ClangScanDeps/working-directory-option.c  | 30 +++++++++++++++++++
 2 files changed, 35 insertions(+), 3 deletions(-)
 create mode 100644 clang/test/ClangScanDeps/working-directory-option.c

diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
index 2b882f8a5e0793..f7c302854a2479 100644
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
@@ -342,6 +342,9 @@ class DependencyScanningAction : public tooling::ToolAction {
     ScanInstance.getHeaderSearchOpts().ModulesIncludeVFSUsage =
         any(OptimizeArgs & ScanningOptimizations::VFS);
 
+    // FileMgr was created before option parsing; set its FileSystemOptions now.
+    FileMgr->getFileSystemOpts() = ScanInstance.getFileSystemOpts();
+
     ScanInstance.setFileManager(FileMgr);
     // Support for virtual file system overlays.
     FileMgr->setVirtualFileSystem(createVFSFromCompilerInvocation(
@@ -624,9 +627,8 @@ bool DependencyScanningWorker::computeDependencies(
       ModifiedCommandLine ? *ModifiedCommandLine : CommandLine;
   auto &FinalFS = ModifiedFS ? ModifiedFS : BaseFS;
 
-  FileSystemOptions FSOpts;
-  FSOpts.WorkingDir = WorkingDirectory.str();
-  auto FileMgr = llvm::makeIntrusiveRefCnt<FileManager>(FSOpts, FinalFS);
+  auto FileMgr =
+      llvm::makeIntrusiveRefCnt<FileManager>(FileSystemOptions{}, FinalFS);
 
   std::vector<const char *> FinalCCommandLine(FinalCommandLine.size(), nullptr);
   llvm::transform(FinalCommandLine, FinalCCommandLine.begin(),
diff --git a/clang/test/ClangScanDeps/working-directory-option.c b/clang/test/ClangScanDeps/working-directory-option.c
new file mode 100644
index 00000000000000..d57497d405d30f
--- /dev/null
+++ b/clang/test/ClangScanDeps/working-directory-option.c
@@ -0,0 +1,30 @@
+// Test that -working-directory works even when it differs from the working
+// directory of the filesystem.
+
+// RUN: rm -rf %t
+// RUN: mkdir -p %t/other
+// RUN: split-file %s %t
+// RUN: sed -e "s|DIR|%/t|g" %t/cdb.json.template > %t/cdb.json
+
+// RUN: clang-scan-deps -compilation-database %t/cdb.json -format experimental-full \
+// RUN:   > %t/deps.json
+
+// RUN: cat %t/deps.json | sed 's:\\\\\?:/:g' | FileCheck %s -DPREFIX=%/t
+
+// CHECK:      "file-deps": [
+// CHECK-NEXT:   "[[PREFIX]]/cwd/t.c"
+// CHECK-NEXT:   "[[PREFIX]]/cwd/relative/h1.h"
+// CHECK-NEXT: ]
+// CHECK-NEXT: "input-file": "[[PREFIX]]/cwd/t.c"
+
+//--- cdb.json.template
+[{
+  "directory": "DIR/other",
+  "command": "clang -c t.c -I relative -working-directory DIR/cwd",
+  "file": "DIR/cwd/t.c"
+}]
+
+//--- cwd/relative/h1.h
+
+//--- cwd/t.c
+#include "h1.h"