Address review comments

Also fix stack-allocated `CommandLine` entries when using a
InplaceCompilationDatabase

Author: aganea

clang/test/ClangScanDeps/response-file-clang-cl.c

@@ -2,33 +2,53 @@
 
 // RUN: rm -rf %t
 // RUN: split-file %s %t
+
+// First run the tests with a .cdb
 // RUN: sed -e "s|DIR|%/t|g" %t/cdb.json.template > %t/cdb.json
-// RUN: echo /Fo%t/tu.obj >> %t/args_nested.rsp
+// RUN: sed -e "s|DIR|%/t|g" %t/args_nested.template > %t/args_nested.rsp
 
-// RUN: echo /c >> %t/args_nested.rsp
-// RUN: clang-scan-deps -compilation-database %t/cdb.json > %t/deps.json
+// RUN: cp %t/args_compilation.rsp %t/args.rsp
+// RUN: clang-scan-deps --compilation-database %t/cdb.json > %t/deps.json
 // RUN: cat %t/deps.json | sed 's:\\\\\?:/:g' | FileCheck -DPREFIX=%/t %s
 
-// RUN: echo /E >> %t/args_nested.rsp
-// RUN: clang-scan-deps -compilation-database %t/cdb.json > %t/deps.json
+// RUN: cp %t/args_preprocess.rsp %t/args.rsp
+// RUN: clang-scan-deps --compilation-database %t/cdb.json > %t/deps.json
 // RUN: cat %t/deps.json | sed 's:\\\\\?:/:g' | FileCheck -DPREFIX=%/t %s
 
+
+// Now run the tests again with a in-place compilation database
+// RUN: cd %t
+
+// RUN: cp args_compilation.rsp args.rsp
+// RUN: clang-scan-deps -o deps.json -- %clang_cl @args.rsp
+// RUN: cat deps.json | sed 's:\\\\\?:/:g' | FileCheck -DPREFIX=%/t %s
+
+// RUN: cp args_preprocess.rsp args.rsp
+// RUN: clang-scan-deps -o deps.json -- %clang_cl @args.rsp
+// RUN: cat deps.json | sed 's:\\\\\?:/:g' | FileCheck -DPREFIX=%/t %s
+
 // Here we ensure that we got a qualified .obj with its full path, since that's what we're passing with /Fo
 // CHECK: [[PREFIX]]/tu.obj:
 
 //--- cdb.json.template
 [{
-  "file": "DIR/t.cpp",
+  "file": "DIR/tu.cpp",
   "directory": "DIR",
   "command": "clang-cl @DIR/args.rsp"
 }]
 
-//--- args.rsp
+//--- args_compilation.rsp
 @args_nested.rsp
-tu.cpp
+/c
+
+//--- args_preprocess.rsp
+@args_nested.rsp
+/E
 
-//--- args_nested.rsp
+//--- args_nested.template
 /I include
+tu.cpp
+/FoDIR/tu.obj
 
 //--- include/header.h
 

clang/tools/clang-scan-deps/ClangScanDeps.cpp

@@ -86,6 +86,8 @@ static bool DeprecatedDriverCommand;
 static ResourceDirRecipeKind ResourceDirRecipe;
 static bool Verbose;
 static bool PrintTiming;
+static llvm::BumpPtrAllocator Alloc;
+static llvm::StringSaver Saver{Alloc};
 static std::vector<const char *> CommandLine;
 
 #ifndef NDEBUG
@@ -99,8 +101,6 @@ static bool RoundTripArgs = DoRoundTripDefault;
 static void ParseArgs(int argc, char **argv) {
   ScanDepsOptTable Tbl;
   llvm::StringRef ToolName = argv[0];
-  llvm::BumpPtrAllocator Alloc;
-  llvm::StringSaver Saver{Alloc};
   llvm::opt::InputArgList Args =
       Tbl.parseArgs(argc, argv, OPT_UNKNOWN, Saver, [&](StringRef Msg) {
         llvm::errs() << Msg << '\n';
@@ -794,13 +794,13 @@ int clang_scan_deps_main(int argc, char **argv, const llvm::ToolContext &) {
 
   // Expand response files in advance, so that we can "see" all the arguments
   // when adjusting below.
-  auto ResponseExpander = expandResponseFiles(std::move(Compilations),
-                                              llvm::vfs::getRealFileSystem());
+  Compilations = expandResponseFiles(std::move(Compilations),
+                                     llvm::vfs::getRealFileSystem());
 
   // The command options are rewritten to run Clang in preprocessor only mode.
   auto AdjustingCompilations =
       std::make_unique<tooling::ArgumentsAdjustingCompilations>(
-          std::move(ResponseExpander));
+          std::move(Compilations));
   ResourceDirectoryCache ResourceDirCache;
 
   AdjustingCompilations->appendArgumentsAdjuster(