[driver] When creating the compiler invocation out of command-line
arguments, force use of clang frontend for the driver.

Fixes rdar://11356765.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@157205 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Driver.cpp b/lib/Driver/Driver.cpp
index 9340ba1..9e3ba84 100644
--- a/lib/Driver/Driver.cpp
+++ b/lib/Driver/Driver.cpp
@@ -59,7 +59,7 @@
     CCPrintOptions(false), CCPrintHeaders(false), CCLogDiagnostics(false),
     CCGenDiagnostics(false), CCCGenericGCCName(""), CheckInputsExist(true),
     CCCUseClang(true), CCCUseClangCXX(true), CCCUseClangCPP(true),
-    CCCUsePCH(true), SuppressMissingInputWarning(false) {
+    ForcedClangUse(false), CCCUsePCH(true), SuppressMissingInputWarning(false) {
   if (IsProduction) {
     // In a "production" build, only use clang on architectures we expect to
     // work.
diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index b0e94bf..53b78d2 100644
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -199,21 +199,25 @@
 
 Tool &Darwin::SelectTool(const Compilation &C, const JobAction &JA,
                          const ActionList &Inputs) const {
-  Action::ActionClass Key;
+  Action::ActionClass Key = JA.getKind();
+  bool useClang = false;
 
   if (getDriver().ShouldUseClangCompiler(C, JA, getTriple())) {
+    useClang = true;
     // Fallback to llvm-gcc for i386 kext compiles, we don't support that ABI.
-    if (Inputs.size() == 1 &&
+    if (!getDriver().shouldForceClangUse() &&
+        Inputs.size() == 1 &&
         types::isCXX(Inputs[0]->getType()) &&
         getTriple().isOSDarwin() &&
         getTriple().getArch() == llvm::Triple::x86 &&
         (C.getArgs().getLastArg(options::OPT_fapple_kext) ||
          C.getArgs().getLastArg(options::OPT_mkernel)))
-      Key = JA.getKind();
-    else
-      Key = Action::AnalyzeJobClass;
-  } else
-    Key = JA.getKind();
+      useClang = false;
+  }
+
+  // FIXME: This seems like a hacky way to choose clang frontend.
+  if (useClang)
+    Key = Action::AnalyzeJobClass;
 
   bool UseIntegratedAs = C.getArgs().hasFlag(options::OPT_integrated_as,
                                              options::OPT_no_integrated_as,
diff --git a/lib/Frontend/ASTUnit.cpp b/lib/Frontend/ASTUnit.cpp
index 7aa9603..d6bdae4 100644
--- a/lib/Frontend/ASTUnit.cpp
+++ b/lib/Frontend/ASTUnit.cpp
@@ -17,12 +17,6 @@
 #include "clang/AST/DeclVisitor.h"
 #include "clang/AST/TypeOrdering.h"
 #include "clang/AST/StmtVisitor.h"
-#include "clang/Driver/Compilation.h"
-#include "clang/Driver/Driver.h"
-#include "clang/Driver/Job.h"
-#include "clang/Driver/ArgList.h"
-#include "clang/Driver/Options.h"
-#include "clang/Driver/Tool.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/FrontendActions.h"
 #include "clang/Frontend/FrontendDiagnostic.h"
diff --git a/lib/Frontend/CreateInvocationFromCommandLine.cpp b/lib/Frontend/CreateInvocationFromCommandLine.cpp
index b477ade..0aca86e 100644
--- a/lib/Frontend/CreateInvocationFromCommandLine.cpp
+++ b/lib/Frontend/CreateInvocationFromCommandLine.cpp
@@ -43,13 +43,17 @@
   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);