Add constexpr to accessors in DenseBase, Quaternions and Translations

Eigen/src/Core/DenseCoeffsBase.h

diff --git a/Eigen/src/Core/DenseCoeffsBase.h b/Eigen/src/Core/DenseCoeffsBase.h
index 48c6d73..30e0aa3 100644
--- a/Eigen/src/Core/DenseCoeffsBase.h
+++ b/Eigen/src/Core/DenseCoeffsBase.h
@@ -89,12 +89,13 @@
    *
    * \sa operator()(Index,Index) const, coeffRef(Index,Index), coeff(Index) const
    */
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType coeff(Index row, Index col) const {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType coeff(Index row, Index col) const {
     eigen_internal_assert(row >= 0 && row < rows() && col >= 0 && col < cols());
     return internal::evaluator<Derived>(derived()).coeff(row, col);
   }
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType coeffByOuterInner(Index outer, Index inner) const {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType coeffByOuterInner(Index outer,
+                                                                                          Index inner) const {
     return coeff(rowIndexByOuterInner(outer, inner), colIndexByOuterInner(outer, inner));
   }
 
@@ -102,7 +103,7 @@
    *
    * \sa operator()(Index,Index), operator[](Index)
    */
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType operator()(Index row, Index col) const {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType operator()(Index row, Index col) const {
     eigen_assert(row >= 0 && row < rows() && col >= 0 && col < cols());
     return coeff(row, col);
   }
@@ -122,7 +123,7 @@
    * \sa operator[](Index) const, coeffRef(Index), coeff(Index,Index) const
    */
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType coeff(Index index) const {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType coeff(Index index) const {
     EIGEN_STATIC_ASSERT(internal::evaluator<Derived>::Flags & LinearAccessBit,
                         THIS_COEFFICIENT_ACCESSOR_TAKING_ONE_ACCESS_IS_ONLY_FOR_EXPRESSIONS_ALLOWING_LINEAR_ACCESS)
     eigen_internal_assert(index >= 0 && index < size());
@@ -137,7 +138,7 @@
    * z() const, w() const
    */
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType operator[](Index index) const {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType operator[](Index index) const {
     EIGEN_STATIC_ASSERT(Derived::IsVectorAtCompileTime,
                         THE_BRACKET_OPERATOR_IS_ONLY_FOR_VECTORS__USE_THE_PARENTHESIS_OPERATOR_INSTEAD)
     eigen_assert(index >= 0 && index < size());
@@ -154,32 +155,32 @@
    * z() const, w() const
    */
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType operator()(Index index) const {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType operator()(Index index) const {
     eigen_assert(index >= 0 && index < size());
     return coeff(index);
   }
 
   /** equivalent to operator[](0).  */
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType x() const { return (*this)[0]; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType x() const { return (*this)[0]; }
 
   /** equivalent to operator[](1).  */
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType y() const {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType y() const {
     EIGEN_STATIC_ASSERT(Derived::SizeAtCompileTime == -1 || Derived::SizeAtCompileTime >= 2, OUT_OF_RANGE_ACCESS);
     return (*this)[1];
   }
 
   /** equivalent to operator[](2).  */
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType z() const {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType z() const {
     EIGEN_STATIC_ASSERT(Derived::SizeAtCompileTime == -1 || Derived::SizeAtCompileTime >= 3, OUT_OF_RANGE_ACCESS);
     return (*this)[2];
   }
 
   /** equivalent to operator[](3).  */
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType w() const {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR CoeffReturnType w() const {
     EIGEN_STATIC_ASSERT(Derived::SizeAtCompileTime == -1 || Derived::SizeAtCompileTime >= 4, OUT_OF_RANGE_ACCESS);
     return (*this)[3];
   }
@@ -361,32 +362,32 @@
    * \sa operator[](Index) const, operator()(Index,Index), x(), y(), z(), w()
    */
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar& operator()(Index index) {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR Scalar& operator()(Index index) {
     eigen_assert(index >= 0 && index < size());
     return coeffRef(index);
   }
 
   /** equivalent to operator[](0).  */
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar& x() { return (*this)[0]; }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR Scalar& x() { return (*this)[0]; }
 
   /** equivalent to operator[](1).  */
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar& y() {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR Scalar& y() {
     EIGEN_STATIC_ASSERT(Derived::SizeAtCompileTime == -1 || Derived::SizeAtCompileTime >= 2, OUT_OF_RANGE_ACCESS);
     return (*this)[1];
   }
 
   /** equivalent to operator[](2).  */
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar& z() {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR Scalar& z() {
     EIGEN_STATIC_ASSERT(Derived::SizeAtCompileTime == -1 || Derived::SizeAtCompileTime >= 3, OUT_OF_RANGE_ACCESS);
     return (*this)[2];
   }
 
   /** equivalent to operator[](3).  */
 
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar& w() {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE EIGEN_CONSTEXPR Scalar& w() {
     EIGEN_STATIC_ASSERT(Derived::SizeAtCompileTime == -1 || Derived::SizeAtCompileTime >= 4, OUT_OF_RANGE_ACCESS);
     return (*this)[3];
   }

Eigen/src/Geometry/Quaternion.h

diff --git a/Eigen/src/Geometry/Quaternion.h b/Eigen/src/Geometry/Quaternion.h
index 8931c4a..1d8ded9 100644
--- a/Eigen/src/Geometry/Quaternion.h
+++ b/Eigen/src/Geometry/Quaternion.h
@@ -57,22 +57,22 @@
   typedef AngleAxis<Scalar> AngleAxisType;
 
   /** \returns the \c x coefficient */
-  EIGEN_DEVICE_FUNC inline CoeffReturnType x() const { return this->derived().coeffs().coeff(0); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline CoeffReturnType x() const { return this->derived().coeffs().coeff(0); }
   /** \returns the \c y coefficient */
-  EIGEN_DEVICE_FUNC inline CoeffReturnType y() const { return this->derived().coeffs().coeff(1); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline CoeffReturnType y() const { return this->derived().coeffs().coeff(1); }
   /** \returns the \c z coefficient */
-  EIGEN_DEVICE_FUNC inline CoeffReturnType z() const { return this->derived().coeffs().coeff(2); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline CoeffReturnType z() const { return this->derived().coeffs().coeff(2); }
   /** \returns the \c w coefficient */
-  EIGEN_DEVICE_FUNC inline CoeffReturnType w() const { return this->derived().coeffs().coeff(3); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline CoeffReturnType w() const { return this->derived().coeffs().coeff(3); }
 
   /** \returns a reference to the \c x coefficient (if Derived is a non-const lvalue) */
-  EIGEN_DEVICE_FUNC inline NonConstCoeffReturnType x() { return this->derived().coeffs().x(); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline NonConstCoeffReturnType x() { return this->derived().coeffs().x(); }
   /** \returns a reference to the \c y coefficient (if Derived is a non-const lvalue) */
-  EIGEN_DEVICE_FUNC inline NonConstCoeffReturnType y() { return this->derived().coeffs().y(); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline NonConstCoeffReturnType y() { return this->derived().coeffs().y(); }
   /** \returns a reference to the \c z coefficient (if Derived is a non-const lvalue) */
-  EIGEN_DEVICE_FUNC inline NonConstCoeffReturnType z() { return this->derived().coeffs().z(); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline NonConstCoeffReturnType z() { return this->derived().coeffs().z(); }
   /** \returns a reference to the \c w coefficient (if Derived is a non-const lvalue) */
-  EIGEN_DEVICE_FUNC inline NonConstCoeffReturnType w() { return this->derived().coeffs().w(); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline NonConstCoeffReturnType w() { return this->derived().coeffs().w(); }
 
   /** \returns a read-only vector expression of the imaginary part (x,y,z) */
   EIGEN_DEVICE_FUNC inline const VectorBlock<const Coefficients, 3> vec() const { return coeffs().template head<3>(); }

Eigen/src/Geometry/Translation.h

diff --git a/Eigen/src/Geometry/Translation.h b/Eigen/src/Geometry/Translation.h
index 956ef56..682c4c7 100644
--- a/Eigen/src/Geometry/Translation.h
+++ b/Eigen/src/Geometry/Translation.h
@@ -69,18 +69,18 @@
   EIGEN_DEVICE_FUNC explicit inline Translation(const VectorType& vector) : m_coeffs(vector) {}
 
   /** \brief Returns the x-translation by value. **/
-  EIGEN_DEVICE_FUNC inline Scalar x() const { return m_coeffs.x(); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Scalar x() const { return m_coeffs.x(); }
   /** \brief Returns the y-translation by value. **/
-  EIGEN_DEVICE_FUNC inline Scalar y() const { return m_coeffs.y(); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Scalar y() const { return m_coeffs.y(); }
   /** \brief Returns the z-translation by value. **/
-  EIGEN_DEVICE_FUNC inline Scalar z() const { return m_coeffs.z(); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Scalar z() const { return m_coeffs.z(); }
 
   /** \brief Returns the x-translation as a reference. **/
-  EIGEN_DEVICE_FUNC inline Scalar& x() { return m_coeffs.x(); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Scalar& x() { return m_coeffs.x(); }
   /** \brief Returns the y-translation as a reference. **/
-  EIGEN_DEVICE_FUNC inline Scalar& y() { return m_coeffs.y(); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Scalar& y() { return m_coeffs.y(); }
   /** \brief Returns the z-translation as a reference. **/
-  EIGEN_DEVICE_FUNC inline Scalar& z() { return m_coeffs.z(); }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Scalar& z() { return m_coeffs.z(); }
 
   EIGEN_DEVICE_FUNC const VectorType& vector() const { return m_coeffs; }
   EIGEN_DEVICE_FUNC VectorType& vector() { return m_coeffs; }