[modules-ts] Fold together -x c++ and -x c++-module at -cc1 level.

The driver needs to know whether it's building a module interface or
implementation unit because it affects which outputs it produces and how it
builds the command pipeline. But the frontend doesn't need to know and should
not care: all it needs to know is what action it is being asked to perform on
the input.

(This is in preparation for permitting -emit-obj to be used on a module
interface unit to produce object code without going via a "full" PCM file.)

llvm-svn: 300611

1 files changed, 18 insertions, 2 deletions

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 4259b629728..b6887b87584 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -649,8 +649,24 @@ static void addDashXForInput(const ArgList &Args, const InputInfo &Input,
   CmdArgs.push_back("-x");
   if (Args.hasArg(options::OPT_rewrite_objc))
     CmdArgs.push_back(types::getTypeName(types::TY_PP_ObjCXX));
-  else
-    CmdArgs.push_back(types::getTypeName(Input.getType()));
+  else {
+    // Map the driver type to the frontend type. This is mostly an identity
+    // mapping, except that the distinction between module interface units
+    // and other source files does not exist at the frontend layer.
+    const char *ClangType;
+    switch (Input.getType()) {
+    case types::TY_CXXModule:
+      ClangType = "c++";
+      break;
+    case types::TY_PP_CXXModule:
+      ClangType = "c++-cpp-output";
+      break;
+    default:
+      ClangType = types::getTypeName(Input.getType());
+      break;
+    }
+    CmdArgs.push_back(ClangType);
+  }
 }
 
 static void appendUserToPath(SmallVectorImpl<char> &Result) {