Add template type diffing to Clang. This feature will provide a better

comparison between two templated types when they both appear in a diagnostic.
Type elision will remove indentical template arguments, which can be disabled
with -fno-elide-type.  Cyan highlighting is applied to the differing types.

For more formatting, -fdiagnostic-show-template-tree will output the template
type as an indented text tree, with differences appearing inline. Template
tree works with or without type elision.

llvm-svn: 159216

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1349,6 +1349,8 @@ bool clang::ParseDiagnosticArgs(DiagnosticOptions &Opts, ArgList &Args,
   Opts.ShowSourceRanges = Args.hasArg(OPT_fdiagnostics_print_source_range_info);
   Opts.ShowParseableFixits = Args.hasArg(OPT_fdiagnostics_parseable_fixits);
   Opts.VerifyDiagnostics = Args.hasArg(OPT_verify);
+  Opts.ElideType = !Args.hasArg(OPT_fno_elide_type);
+  Opts.ShowTemplateTree = Args.hasArg(OPT_fdiagnostics_show_template_tree);
   Opts.ErrorLimit = Args.getLastArgIntValue(OPT_ferror_limit, 0, Diags);
   Opts.MacroBacktraceLimit
     = Args.getLastArgIntValue(OPT_fmacro_backtrace_limit,