Implement -MG.  Fixes PR9613

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@134996 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Basic/DiagnosticDriverKinds.td b/include/clang/Basic/DiagnosticDriverKinds.td
index 409c6a2..e33b67e 100644
--- a/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/include/clang/Basic/DiagnosticDriverKinds.td
@@ -86,6 +86,8 @@
   "cannot specify both '-fobjc-arc' and '%0'">;
 def err_arc_nonfragile_abi : Error<
   "-fobjc-arc is not supported with fragile abi">;
+def err_drv_mg_requires_m_or_mm : Error<
+  "option '-MG' requires '-M' or '-MM'">;
 
 def warn_c_kext : Warning<
   "ignoring -fapple-kext which is valid for c++ and objective-c++ only">;
diff --git a/include/clang/Basic/DiagnosticLexKinds.td b/include/clang/Basic/DiagnosticLexKinds.td
index 3514cca..38d6a80 100644
--- a/include/clang/Basic/DiagnosticLexKinds.td
+++ b/include/clang/Basic/DiagnosticLexKinds.td
@@ -178,7 +178,7 @@
 
 def err_pp_invalid_directive : Error<"invalid preprocessing directive">;
 def err_pp_hash_error : Error<"#error%0">;
-def err_pp_file_not_found : Error<"'%0' file not found">, DefaultFatal;
+def warn_pp_file_not_found : Warning<"'%0' file not found">, DefaultFatal;
 def err_pp_error_opening_file : Error<
   "error opening file '%0': %1">, DefaultFatal;
 def err_pp_empty_filename : Error<"empty filename">;
diff --git a/include/clang/Driver/CC1Options.td b/include/clang/Driver/CC1Options.td
index 6befc8c..8cadbe9 100644
--- a/include/clang/Driver/CC1Options.td
+++ b/include/clang/Driver/CC1Options.td
@@ -208,6 +208,7 @@
 def MT : Separate<"-MT">, HelpText<"Specify target for dependency">;
 def MP : Flag<"-MP">,
   HelpText<"Create phony target for each dependency (other than main file)">;
+def MG : Flag<"-MG">, HelpText<"Add missing headers to dependency list">;
 
 //===----------------------------------------------------------------------===//
 // Diagnostic Options
diff --git a/include/clang/Frontend/DependencyOutputOptions.h b/include/clang/Frontend/DependencyOutputOptions.h
index 35aa6c6..1e22c22 100644
--- a/include/clang/Frontend/DependencyOutputOptions.h
+++ b/include/clang/Frontend/DependencyOutputOptions.h
@@ -24,6 +24,7 @@
   unsigned UsePhonyTargets : 1;      ///< Include phony targets for each
                                      /// dependency, which can avoid some 'make'
                                      /// problems.
+  unsigned AddMissingHeaderDeps : 1; ///< Add missing headers to dependency list
 
   /// The file to write dependency output to.
   std::string OutputFile;
@@ -43,6 +44,7 @@
     IncludeSystemHeaders = 0;
     ShowHeaderIncludes = 0;
     UsePhonyTargets = 0;
+    AddMissingHeaderDeps = 0;
   }
 };