Devirtualize ArgList's dtor now that -Wvirtual-dtor and C++11 allow a better way to describe this situation

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240238 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Option/ArgList.h

@@ -14,6 +14,7 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
+#include "llvm/Option/Arg.h"
 #include "llvm/Option/OptSpecifier.h"
 #include "llvm/Option/Option.h"
 #include <list>
@@ -23,7 +24,6 @@
 
 namespace llvm {
 namespace opt {
-class Arg;
 class ArgList;
 class Option;
 
@@ -110,10 +110,9 @@ private:
 protected:
   // Default ctor provided explicitly as it is not provided implicitly due to
   // the presence of the (deleted) copy ctor above.
-  ArgList() { }
-  // Virtual to provide a vtable anchor and because -Wnon-virtua-dtor warns, not
-  // because this type is ever actually destroyed polymorphically.
-  virtual ~ArgList();
+  ArgList() = default;
+  // Protect the dtor to ensure this type is never destroyed polymorphically.
+  ~ArgList() = default;
 
 public:
 
@@ -299,7 +298,7 @@ public:
   /// @}
 };
 
-class InputArgList : public ArgList  {
+class InputArgList final : public ArgList {
 private:
   /// List of argument strings used by the contained Args.
   ///
@@ -320,7 +319,7 @@ private:
 
 public:
   InputArgList(const char* const *ArgBegin, const char* const *ArgEnd);
-  ~InputArgList() override;
+  ~InputArgList();
 
   const char *getArgString(unsigned Index) const override {
     return ArgStrings[Index];
@@ -346,7 +345,7 @@ public:
 
 /// DerivedArgList - An ordered collection of driver arguments,
 /// whose storage may be in another argument list.
-class DerivedArgList : public ArgList {
+class DerivedArgList final : public ArgList {
   const InputArgList &BaseArgs;
 
   /// The list of arguments we synthesized.
@@ -355,7 +354,6 @@ class DerivedArgList : public ArgList {
 public:
   /// Construct a new derived arg list from \p BaseArgs.
   DerivedArgList(const InputArgList &BaseArgs);
-  ~DerivedArgList() override;
 
   const char *getArgString(unsigned Index) const override {
     return BaseArgs.getArgString(Index);

lib/Option/ArgList.cpp

@@ -33,9 +33,6 @@ void arg_iterator::SkipToNextArg() {
   }
 }
 
-ArgList::~ArgList() {
-}
-
 void ArgList::append(Arg *A) {
   Args.push_back(A);
 }
@@ -358,8 +355,6 @@ const char *InputArgList::MakeArgStringRef(StringRef Str) const {
 DerivedArgList::DerivedArgList(const InputArgList &BaseArgs)
     : BaseArgs(BaseArgs) {}
 
-DerivedArgList::~DerivedArgList() {}
-
 const char *DerivedArgList::MakeArgStringRef(StringRef Str) const {
   return BaseArgs.MakeArgString(Str);
 }