Define and use IteratorRange

src/MemoryX.h

@@ -727,4 +727,16 @@ Final_action<F> finally (F f)
    return Final_action<F>(f);
 }
 
+/*
+ * A convenience for use with range-for
+ */
+template <typename Iterator>
+struct IteratorRange : public std::pair<Iterator, Iterator> {
+   IteratorRange (Iterator &&a, Iterator &&b)
+      : std::pair<Iterator, Iterator> { std::move(a), std::move(b) } {}
+
+   Iterator begin() const { return this->first; }
+   Iterator end() const { return this->second; }
+};
+
 #endif // __AUDACITY_MEMORY_X_H__

src/Tags.cpp

@@ -443,7 +443,7 @@ wxString Tags::GetTag(const wxString & name) const
 
 Tags::Iterators Tags::GetRange() const
 {
-   return std::make_pair(mMap.begin(), mMap.end());
+   return { mMap.begin(), mMap.end() };
 }
 
 void Tags::SetTag(const wxString & name, const wxString & value)

src/Tags.h

@@ -104,13 +104,7 @@ class AUDACITY_DLL_API Tags final : public XMLTagHandler {
    bool HasTag(const wxString & name) const;
    wxString GetTag(const wxString & name) const;
 
-   using IterPair = std::pair<TagMap::const_iterator, TagMap::const_iterator>;
+   using Iterators = IteratorRange<TagMap::const_iterator>;
-   struct Iterators : public IterPair {
-      Iterators(IterPair p) : IterPair(p) {}
-      // Define begin() and end() for convenience in range-for
-      auto begin() -> decltype(first) const { return first; }
-      auto end() -> decltype(second) const { return second; }
-   };
    Iterators GetRange() const;
 
    void SetTag(const wxString & name, const wxString & value);