Options: Use erase_if to remove Args from the list.

While there make getOption return a const reference so we don't have to put it
on the stack when calling methods on it. No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209088 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Option/Arg.h

@@ -67,7 +67,7 @@ class Arg {
       const char *Value0, const char *Value1, const Arg *BaseArg = nullptr);
   ~Arg();
 
-  const Option getOption() const { return Opt; }
+  const Option &getOption() const { return Opt; }
   StringRef getSpelling() const { return Spelling; }
   unsigned getIndex() const { return Index; }
 

lib/Option/ArgList.cpp

@@ -41,14 +41,9 @@ void ArgList::append(Arg *A) {
 }
 
 void ArgList::eraseArg(OptSpecifier Id) {
-  for (iterator it = begin(), ie = end(); it != ie; ) {
-    if ((*it)->getOption().matches(Id)) {
-      it = Args.erase(it);
-      ie = end();
-    } else {
-      ++it;
-    }
-  }
+  Args.erase(std::remove_if(begin(), end(),
+                            [=](Arg *A) { return A->getOption().matches(Id); }),
+             end());
 }
 
 Arg *ArgList::getLastArgNoClaim(OptSpecifier Id) const {