Refactoring cl::list_storage from "is a" to "has a" std::vector.

[beanz]

Summary

This isn't necessarily an ideal change, and I want to at least reduce the API surface area, but for the new API we really shouldn't be relying on cl::list being a std::vector.

[chandlerc]

Yuck. But I agree with you completely. I can't bring myself to say this "looks good" but it looks *right*. Go for it.

include/llvm/Support/CommandLine.h

1291 ↗

(On Diff #26696)

Add a FIXME comment to indicate that we want to reduce this over time to a reasonably narrow API?

llvm/trunk/include/llvm/Support/CommandLine.h

public:
 
   template <class T> void addValue(const T &V) {
     assert(Location != 0 && "cl::location(...) not specified for a command "
                             "line option with external storage!");
     Location->push_back(V);
   }
 };
 
-// Define how to hold a class type object, such as a string.  Since we can
-// inherit from a class, we do so.  This makes us exactly compatible with the
-// object in all cases that it is used.
+// Define how to hold a class type object, such as a string.
+// Originally this code inherited from std::vector. In transitioning to a new
+// API for command line options we should change this. The new implementation
+// of this list_storage specialization implements the minimum subset of the
+// std::vector API required for all the current clients.
 //
-template <class DataType>
-class list_storage<DataType, bool> : public std::vector<DataType> {
+// FIXME: Reduce this API to a more narrow subset of std::vector
+//
+template <class DataType> class list_storage<DataType, bool> {
+  std::vector<DataType> Storage;
+
 public:
-  template <class T> void addValue(const T &V) {
-    std::vector<DataType>::push_back(V);
+  typedef typename std::vector<DataType>::iterator iterator;
+
+  iterator begin() { return Storage.begin(); }
+  iterator end() { return Storage.end(); }
+
+  typedef typename std::vector<DataType>::const_iterator const_iterator;
+  const_iterator begin() const { return Storage.begin(); }
+  const_iterator end() const { return Storage.end(); }
+
+  typedef typename std::vector<DataType>::size_type size_type;
+  size_type size() const { return Storage.size(); }
+
+  bool empty() const { return Storage.empty(); }
+
+  void push_back(const DataType &value) { Storage.push_back(value); }
+  void push_back(DataType &&value) { Storage.push_back(value); }
+
+  typedef typename std::vector<DataType>::reference reference;
+  typedef typename std::vector<DataType>::const_reference const_reference;
+  reference operator[](size_type pos) { return Storage[pos]; }
+  const_reference operator[](size_type pos) const { return Storage[pos]; }
+
+  iterator erase(const_iterator pos) { return Storage.erase(pos); }
+  iterator erase(const_iterator first, const_iterator last) {
+    return Storage.erase(first, last);
+  }
+
+  iterator insert(const_iterator pos, const DataType &value) {
+    return Storage.insert(pos, value);
+  }
+  iterator insert(const_iterator pos, DataType &&value) {
+    return Storage.insert(pos, value);
   }
+
+  reference front() { return Storage.front(); }
+  const_reference front() const { return Storage.front(); }
+
+  operator std::vector<DataType>&() { return Storage; }
+  operator ArrayRef<DataType>() { return Storage; }
+  std::vector<DataType> *operator&() { return &Storage; }
+  const std::vector<DataType> *operator&() const { return &Storage; }
+
+  template <class T> void addValue(const T &V) { Storage.push_back(V); }
 };
 
 //===----------------------------------------------------------------------===//
 // list - A list of command line options.
 //
 template <class DataType, class Storage = bool,
           class ParserClass = parser<DataType>>
 class list : public Option, public list_storage<DataType, Storage> {