[CommandLineParser] Add DefaultOption flag

Summary: Add DefaultOption flag to CommandLineParser which provides a
default option or alias, but allows users to override it for some
other purpose as needed.

Also, add `-h` as a default alias to `-help`, which can be seamlessly
overridden by applications like llvm-objdump and llvm-readobj which
use `-h` as an alias for other options.

Reviewers: alexfh, klimek

Reviewed By: klimek

Subscribers: MaskRay, mehdi_amini, inglorion, dexonsmith, hiraditya, llvm-commits, jhenderson, arphaman, cfe-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D59746

llvm-svn: 358337

1 files changed, 0 insertions, 2 deletions

diff --git a/clang/lib/Tooling/CommonOptionsParser.cpp b/clang/lib/Tooling/CommonOptionsParser.cpp
index f38542dac6a..5faa1d7bdb2 100644
--- a/clang/lib/Tooling/CommonOptionsParser.cpp
+++ b/clang/lib/Tooling/CommonOptionsParser.cpp
@@ -83,8 +83,6 @@ std::vector<CompileCommand> ArgumentsAdjustingCompilations::adjustCommands(
 llvm::Error CommonOptionsParser::init(
     int &argc, const char **argv, cl::OptionCategory &Category,
     llvm::cl::NumOccurrencesFlag OccurrencesFlag, const char *Overview) {
-  static cl::opt<bool> Help("h", cl::desc("Alias for -help"), cl::Hidden,
-                            cl::sub(*cl::AllSubCommands));
 
   static cl::opt<std::string> BuildPath("p", cl::desc("Build path"),
                                         cl::Optional, cl::cat(Category),