Initial work to improve documentation for Clang's diagnostics, from Matthieu Monrocq

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@129614 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index f288c4e..66f8b0b 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -1737,6 +1737,11 @@
   if (!Args.hasFlag(options::OPT_fdiagnostics_fixit_info,
                     options::OPT_fno_diagnostics_fixit_info))
     CmdArgs.push_back("-fno-diagnostics-fixit-info");
+  
+  // Enable -fdiagnostics-show-name by default.
+  if (Args.hasFlag(options::OPT_fdiagnostics_show_name,
+                   options::OPT_fno_diagnostics_show_name, false))
+    CmdArgs.push_back("-fdiagnostics-show-name");
 
   // Enable -fdiagnostics-show-option by default.
   if (Args.hasFlag(options::OPT_fdiagnostics_show_option,