[clang(d)] Include/Exclude CLDXC options properly

[kadircet]

Summary

This handles the new CLDXC options that was introduced in
https://reviews.llvm.org/D128462 inside clang-tooling to make sure cl driver
mode is not broken.

Fixes https://github.com/clangd/clangd/issues/1292.

[kadircet]

asked for a backport for 15.0.1 in https://github.com/llvm/llvm-project/issues/57779

clang-tools-extra/clangd/CompileCommands.cpp

void CommandMangler::adjust(std::vector<std::string> &Cmd,
   // everything it could parse in ArgList. So we just ignore those counts.
   unsigned IgnoredCount;
   // Drop the executable name, as ParseArgs doesn't expect it. This means
   // indices are actually of by one between ArgList and OriginalArgs.
   llvm::opt::InputArgList ArgList;
   ArgList = OptTable.ParseArgs(
       llvm::makeArrayRef(OriginalArgs).drop_front(), IgnoredCount, IgnoredCount,
       /*FlagsToInclude=*/
-      IsCLMode ? (driver::options::CLOption | driver::options::CoreOption)
+      IsCLMode ? (driver::options::CLOption | driver::options::CoreOption |
+                  driver::options::CLDXCOption)
                : /*everything*/ 0,
       /*FlagsToExclude=*/driver::options::NoDriverOption |
-          (IsCLMode ? 0 : driver::options::CLOption));
+          (IsCLMode
+               ? 0
+               : (driver::options::CLOption | driver::options::CLDXCOption)));
 
   llvm::SmallVector<unsigned, 1> IndicesToDrop;
   // Having multiple architecture options (e.g. when building fat binaries)
   // results in multiple compiler jobs, which clangd cannot handle. In such
   // cases strip all the `-arch` options and fallback to default architecture.
   // As there are no signals to figure out which one user actually wants. They
   // can explicitly specify one through `CompileFlags.Add` if need be.
   unsigned ArchOptCount = 0;

clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp

 }
 
 TEST(CommandMangler, EmptyArgs) {
   const auto Mangler = CommandMangler::forTests();
   std::vector<std::string> Args = {};
   // Make sure we don't crash.
   Mangler.adjust(Args, "foo.cc");
 }
+
+TEST(CommandMangler, PathsAsPositional) {
+  const auto Mangler = CommandMangler::forTests();
+  std::vector<std::string> Args = {
+      "clang",
+      "--driver-mode=cl",
+      "-I",
+      "foo",
+  };
+  // Make sure we don't crash.
+  Mangler.adjust(Args, "a.cc");
+  EXPECT_THAT(Args, Contains("foo"));
+}
 } // namespace
 } // namespace clangd
 } // namespace clang

clang/lib/Tooling/InterpolatingCompilationDatabase.cpp

TransferableCommand(CompileCommand C)
     if (!OldArgs.empty())
       Cmd.CommandLine.emplace_back(OldArgs.front());
     for (unsigned Pos = 1; Pos < OldArgs.size();) {
       using namespace driver::options;
 
       const unsigned OldPos = Pos;
       std::unique_ptr<llvm::opt::Arg> Arg(OptTable.ParseOneArg(
           ArgList, Pos,
-          /* Include */ ClangCLMode ? CoreOption | CLOption : 0,
-          /* Exclude */ ClangCLMode ? 0 : CLOption));
+          /* Include */ ClangCLMode ? CoreOption | CLOption | CLDXCOption : 0,
+          /* Exclude */ ClangCLMode ? 0 : CLOption | CLDXCOption));
 
       if (!Arg)
         continue;
 
       const llvm::opt::Option &Opt = Arg->getOption();
 
       // Strip input and output files.
       if (Opt.matches(OPT_INPUT) || Opt.matches(OPT_o) ||