[driver] When creating the compiler invocation out of command-line

arguments, force use of clang frontend for the driver.

Fixes rdar://11356765.

llvm-svn: 157205

clang/lib/Frontend/CreateInvocationFromCommandLine.cpp

@@ -43,13 +43,17 @@ clang::createInvocationFromCommandLine(ArrayRef<const char *> ArgList,
   Args.push_back("<clang>"); // FIXME: Remove dummy argument.
   Args.insert(Args.end(), ArgList.begin(), ArgList.end());
 
-  // FIXME: Find a cleaner way to force the driver into restricted modes. We
-  // also want to force it to use clang.
+  // FIXME: Find a cleaner way to force the driver into restricted modes.
   Args.push_back("-fsyntax-only");
 
   // FIXME: We shouldn't have to pass in the path info.
   driver::Driver TheDriver("clang", llvm::sys::getDefaultTargetTriple(),
                            "a.out", false, *Diags);
+  // Force driver to use clang.
+  // FIXME: This seems like a hack. Maybe the "Clang" tool subclass should be
+  // available for using it to get the arguments, thus avoiding the overkill
+  // of using the driver.
+  TheDriver.setForcedClangUse();
 
   // Don't check that inputs exist, they may have been remapped.
   TheDriver.setCheckInputsExist(false);