Fixed another occurance of static non-trivial construction

Signed-off-by: Nick Avramoussis <4256455+Idclip@users.noreply.github.com>

Author: Idclip

openvdb/openvdb/math/ConjGradient.h

@@ -245,7 +245,7 @@ class SparseStencilMatrix
     class ConstRow;
     class RowEditor;
 
-    static const ValueType sZeroValue;
+    static inline constexpr ValueType sZeroValue = zeroVal<ValueType>();
 
     /// Construct an @a n x @a n matrix with at most @a STENCIL_SIZE nonzero elements per row.
     SparseStencilMatrix(SizeType n);
@@ -814,10 +814,6 @@ Vector<T>::str() const
 ////////////////////////////////////////
 
 
-template<typename ValueType, SizeType STENCIL_SIZE>
-const ValueType SparseStencilMatrix<ValueType, STENCIL_SIZE>::sZeroValue = zeroVal<ValueType>();
-
-
 template<typename ValueType, SizeType STENCIL_SIZE>
 inline
 SparseStencilMatrix<ValueType, STENCIL_SIZE>::SparseStencilMatrix(SizeType numRows)

openvdb/openvdb/math/Math.h

@@ -67,11 +67,11 @@ namespace OPENVDB_VERSION_NAME {
 /// @note A zeroVal<T>() specialization must be defined for each @c ValueType T
 /// that cannot be constructed using the form @c T(0).  For example, @c std::string(0)
 /// treats 0 as @c nullptr and throws a @c std::logic_error.
-template<typename T> inline T zeroVal() { return T(0); }
+template<typename T> inline constexpr T zeroVal() { return T(0); }
 /// Return the @c std::string value that corresponds to zero.
 template<> inline std::string zeroVal<std::string>() { return ""; }
 /// Return the @c bool value that corresponds to zero.
-template<> inline bool zeroVal<bool>() { return false; }
+template<> inline constexpr bool zeroVal<bool>() { return false; }
 
 namespace math {