Handle option aliases in a better way.

In this way, we don't need to know which options have aliases.

llvm-svn: 308519

Author: rui314

lld/COFF/Driver.cpp

@@ -201,7 +201,7 @@ void LinkerDriver::parseDirectives(StringRef S) {
   opt::InputArgList Args = Parser.parse(S);
 
   for (auto *Arg : Args) {
-    switch (Arg->getOption().getID()) {
+    switch (Arg->getOption().getUnaliasedOption().getID()) {
     case OPT_alternatename:
       parseAlternateName(Arg->getValue());
       break;

lld/ELF/Driver.cpp

@@ -804,14 +804,13 @@ static bool getBinaryOption(StringRef S) {
 
 void LinkerDriver::createFiles(opt::InputArgList &Args) {
   for (auto *Arg : Args) {
-    switch (Arg->getOption().getID()) {
+    switch (Arg->getOption().getUnaliasedOption().getID()) {
     case OPT_l:
       addLibrary(Arg->getValue());
       break;
     case OPT_INPUT:
       addFile(Arg->getValue(), /*WithLOption=*/false);
       break;
-    case OPT_alias_script_T:
     case OPT_script:
       if (Optional<MemoryBufferRef> MB = readFile(Arg->getValue()))
         readLinkerScript(*MB);