BUG: Tuple2 construct null with uninitialized value

Had this:

    Tuple2() {}

Instead of:

    Tuple2() : f_(), s_() {}

which is the same as

    Tuple2() = default;

This meant that Tuple2<scalar, scalar>() was not being zero-initialized

src/OpenFOAM/primitives/Pair/Pair.H

@@ -61,8 +61,8 @@ public:
 
     // Constructors
 
-        //- Null constructor
-        inline Pair();
+        //- Construct null
+        Pair() = default;
 
         //- Construct from components
         inline Pair(const T& f, const T& s);

src/OpenFOAM/primitives/Pair/PairI.H

@@ -45,11 +45,6 @@ inline int Foam::Pair<T>::compare(const Pair<T>& a, const Pair<T>& b)
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
-template<class T>
-inline Foam::Pair<T>::Pair()
-{}
-
-
 template<class T>
 inline Foam::Pair<T>::Pair(const T& f, const T& s)
 {

src/OpenFOAM/primitives/Tuple2/Tuple2.H

@@ -57,7 +57,7 @@ inline Ostream& operator<<(Ostream& os, const Tuple2<Type1, Type2>& t2);
 
 
 /*---------------------------------------------------------------------------*\
-                           class Tuple2 Declaration
+                           Class Tuple2 Declaration
 \*---------------------------------------------------------------------------*/
 
 template<class Type1, class Type2>
@@ -81,9 +81,8 @@ public:
 
     // Constructors
 
-        //- Null constructor for lists and hashes
-        inline Tuple2()
-        {}
+        //- Construct null
+        inline Tuple2() = default;
 
         //- Construct from components
         inline Tuple2(const Type1& f, const Type2& s)