rdar://81632946 [libclang][deps] Accept only driver invocations, don't modify them

(cherry picked from commit 7c44674)

Author: jansvoboda11

clang/include/clang/Tooling/DependencyScanning/DependencyScanningWorker.h

@@ -67,6 +67,11 @@ class DependencyScanningWorker {
                                   const CompilationDatabase &CDB,
                                   DependencyConsumer &Consumer);
 
+  /// Run the dependency scanning tool for a given clang driver invocation, and
+  /// report the discovered dependencies to the provided consumer.
+  ///
+  /// \returns A \c StringError with the diagnostic output if clang errors
+  /// occurred, success otherwise.
   llvm::Error
   computeDependenciesForClangInvocation(StringRef WorkingDirectory,
                                         ArrayRef<std::string> Arguments,

clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp

@@ -327,25 +327,9 @@ llvm::Error DependencyScanningWorker::computeDependencies(
 llvm::Error DependencyScanningWorker::computeDependenciesForClangInvocation(
     StringRef WorkingDirectory, ArrayRef<std::string> Arguments,
     DependencyConsumer &Consumer) {
-  RealFS->setCurrentWorkingDirectory(WorkingDirectory);
-  return runWithDiags(DiagOpts.get(), [&](DiagnosticConsumer &DC) {
-    IntrusiveRefCntPtr<DiagnosticIDs> DiagID = new DiagnosticIDs();
-    IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
-    DiagnosticsEngine Diags(DiagID, &*DiagOpts, &DC, /*ShouldOwnClient=*/false);
-
-    llvm::opt::ArgStringList CC1Args;
-    for (const auto &Arg : Arguments)
-      CC1Args.push_back(Arg.c_str());
-    std::unique_ptr<CompilerInvocation> Invocation(
-        newInvocation(&Diags, CC1Args, /*BinaryName=*/nullptr));
-
-    DependencyScanningAction Action(WorkingDirectory, Consumer, DepFS,
-                                    PPSkipMappings.get(), Format);
-
-    llvm::IntrusiveRefCntPtr<FileManager> FM = Files;
-    if (!FM)
-      FM = new FileManager(FileSystemOptions(), RealFS);
-    return Action.runInvocation(std::move(Invocation), FM.get(),
-                                PCHContainerOps, &DC);
-  });
+  std::string Input("dependency-scanner-fake-input-file");
+  StringRef Output("dependency-scanner-fake-output-file");
+  SingleCommandCompilationDatabase CDB(
+      CompileCommand(WorkingDirectory, Input, Arguments, Output));
+  return computeDependencies(Input, WorkingDirectory, CDB, Consumer);
 }

clang/test/Index/Core/scan-deps.m

@@ -1,10 +1,3 @@
-// RUN: rm -rf %t.mcp
-// RUN: echo %S > %t.result
-// RUN: c-index-test core --scan-deps %S -- %clang -cc1 -I %S/Inputs/module \
-// RUN:     -fmodules -fmodules-cache-path=%t.mcp -fimplicit-module-maps \
-// RUN:     -o FoE.o -x objective-c %s >> %t.result
-// RUN: cat %t.result | sed 's/\\/\//g' | FileCheck %s
-
 // Use driver arguments.
 // RUN: rm -rf %t.mcp
 // RUN: echo %S > %t.result

clang/tools/libclang/CDependencies.cpp

@@ -221,23 +221,7 @@ getFileDependencies(CXDependencyScannerWorker W, int argc,
 
   DependencyScanningWorker *Worker = unwrap(W);
 
-  std::vector<std::string> Compilation;
-  if (StringRef(argv[1]) == "-cc1")
-    for (int i = 2; i < argc; ++i)
-      Compilation.push_back(argv[i]);
-  else {
-    // Run the driver to get -cc1 args.
-    ArrayRef<const char *> CArgs = llvm::makeArrayRef(argv, argv+argc);
-    IntrusiveRefCntPtr<DiagnosticsEngine>
-    Diags(CompilerInstance::createDiagnostics(new DiagnosticOptions));
-    auto CI = createInvocationFromCommandLine(CArgs, Diags, /*VFS=*/nullptr,
-      /*ShouldRecoverOnErrors=*/false, &Compilation);
-    if (!CI) {
-      if (error)
-        *error = cxstring::createRef("failed creating 'cc1' arguments");
-      return nullptr;
-    }
-  }
+  std::vector<std::string> Compilation{argv, argv + argc};
 
   if (Worker->getFormat() == ScanningOutputFormat::Full)
     return getFullDependencies(Worker, Compilation, WorkingDirectory, MDC,