[clang][IncludeTree] Do not preserve working directory from scanning

clang incldue-tree has been consistently using absolute path to encode
all the inputs so there is no need to preserve `-working-directory`
option from the scanner.

This does affect output paths so make sure the output paths are updated
as well to absolute path.

Author: cachemeifyoucan

clang/lib/Tooling/DependencyScanning/ScanAndUpdateArgs.cpp

@@ -11,14 +11,24 @@
 #include "clang/Frontend/CompilerInvocation.h"
 #include "clang/Lex/HeaderSearchOptions.h"
 #include "clang/Tooling/DependencyScanning/DependencyScanningTool.h"
-#include "llvm/CAS/CachingOnDiskFileSystem.h"
 #include "llvm/CAS/ObjectStore.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/PrefixMapper.h"
 
 using namespace clang;
 using namespace clang::tooling::dependencies;
 using llvm::Error;
 
+static void updateRelativePath(std::string &Path,
+                               const std::string &WorkingDir) {
+  if (Path.empty() || llvm::sys::path::is_absolute(Path) || WorkingDir.empty())
+    return;
+
+  SmallString<128> PathStorage(WorkingDir);
+  llvm::sys::path::append(PathStorage, Path);
+  Path = PathStorage.str();
+}
+
 void tooling::dependencies::configureInvocationForCaching(
     CompilerInvocation &CI, CASOptions CASOpts, std::string InputID,
     CachingInputKind InputKind, std::string WorkingDir) {
@@ -92,6 +102,14 @@ void tooling::dependencies::configureInvocationForCaching(
     }
     // Clear APINotes options.
     CI.getAPINotesOpts().ModuleSearchPaths = {};
+
+    // Update output paths, and clear working directory.
+    auto CWD = FileSystemOpts.WorkingDir;
+    updateRelativePath(FrontendOpts.OutputFile, CWD);
+    updateRelativePath(CI.getDiagnosticOpts().DiagnosticSerializationFile, CWD);
+    updateRelativePath(CI.getDiagnosticOpts().DiagnosticLogFile, CWD);
+    updateRelativePath(CI.getDependencyOutputOpts().OutputFile, CWD);
+    FileSystemOpts.WorkingDir.clear();
     break;
   }
   case CachingInputKind::FileSystemRoot: {

clang/test/ClangScanDeps/include-tree-working-directory.c

@@ -11,6 +11,8 @@
 // RUN: %clang @%t/tu.rsp -Rcompile-job-cache 2>&1 | FileCheck %s -check-prefix=CACHE-MISS
 // RUN: %clang @%t/tu.rsp -Rcompile-job-cache 2>&1 | FileCheck %s -check-prefix=CACHE-HIT
 // RUN: ls %t/t.o
+// RUN: ls %t/t.d
+// RUN: ls %t/t.dia
 
 // CACHE-MISS: remark: compile job cache miss
 // CACHE-HIT: remark: compile job cache hit
@@ -25,10 +27,26 @@
 // CHECK: [[PREFIX]]/t.c llvmcas://
 // CHECK: [[PREFIX]]/relative/h1.h llvmcas://
 
+/// Using a different working directory should cache hit as well.
+/// FIXME: Working directory affects some codegen options added by clang driver, preserve them to make sure the cache hit.
+// RUN: sed -e "s|DIR|%/t|g" %t/cdb2.json.template > %t/cdb2.json
+// RUN: clang-scan-deps -compilation-database %t/cdb2.json -format experimental-include-tree-full -cas-path %t/cas \
+// RUN:   > %t/deps2.json
+// RUN: %deps-to-rsp %t/deps2.json --tu-index 0 > %t/tu2.rsp
+// RUN: %clang @%t/tu2.rsp -Rcompile-job-cache 2>&1 | FileCheck %s -check-prefix=CACHE-HIT
+
+
 //--- cdb.json.template
 [{
   "directory": "DIR/other",
-  "command": "clang -c t.c -I relative -working-directory DIR -o t.o",
+  "command": "clang -c t.c -I relative -working-directory DIR -o t.o -MD -serialize-diagnostics t.dia",
+  "file": "DIR/t.c"
+}]
+
+//--- cdb2.json.template
+[{
+  "directory": "DIR/other",
+  "command": "clang -c DIR/t.c -I DIR/relative -working-directory DIR/other -o DIR/t2.o -MD -serialize-diagnostics DIR/t2.dia -fdebug-compilation-dir=DIR -fcoverage-compilation-dir=DIR",
   "file": "DIR/t.c"
 }]