Fix compilation of Vector::operator()(enum) by treating enums as Index

3 files changed, 24 insertions, 6 deletions

diff --git a/Eigen/src/Core/util/Macros.h b/Eigen/src/Core/util/Macros.h
index b63ea2697..caedb0b3a 100644
--- a/Eigen/src/Core/util/Macros.h
+++ b/Eigen/src/Core/util/Macros.h
@@ -410,6 +410,16 @@
 #endif
 #endif
 
+// Does the compiler support type_trais?
+#ifndef EIGEN_HAS_TYPE_TRAITS
+#if EIGEN_MAX_CPP_VER>=11 && (EIGEN_HAS_CXX11 || __has_feature(is_enum) || EIGEN_COMP_MSVC >= 1700)
+#define EIGEN_HAS_TYPE_TRAITS 1
+#define EIGEN_INCLUDE_TYPE_TRAITS
+#else
+#define EIGEN_HAS_TYPE_TRAITS 0
+#endif
+#endif
+
 // Does the compiler support variadic templates?
 #ifndef EIGEN_HAS_VARIADIC_TEMPLATES
 #if EIGEN_MAX_CPP_VER>=11 && (__cplusplus > 199711L || EIGEN_COMP_MSVC >= 1900) \
diff --git a/Eigen/src/Core/util/XprHelper.h b/Eigen/src/Core/util/XprHelper.h
index 4b337f29f..c88f1dbb9 100644
--- a/Eigen/src/Core/util/XprHelper.h
+++ b/Eigen/src/Core/util/XprHelper.h
@@ -34,6 +34,16 @@ inline IndexDest convert_index(const IndexSrc& idx) {
   return IndexDest(idx);
 }
 
+// true if T can be considered as an integral index (i.e., and integral type or enum)
+template<typename T> struct is_valid_index_type
+  : std::integral_constant<bool,
+#if EIGEN_HAS_TYPE_TRAITS
+   internal::is_integral<T>::value || std::is_enum<T>::value
+#else
+  // without C++11, we use is_convertible to Index instead of is_integral in order to treat enums as Index.
+  internal::is_convertible<T,Index>::value
+#endif
+> {};
 
 // promote_scalar_arg is an helper used in operation between an expression and a scalar, like:
 //    expression * scalar
diff --git a/Eigen/src/plugins/IndexedViewMethods.h b/Eigen/src/plugins/IndexedViewMethods.h
index 22c1666c5..215bd0530 100644
--- a/Eigen/src/plugins/IndexedViewMethods.h
+++ b/Eigen/src/plugins/IndexedViewMethods.h
@@ -55,9 +55,7 @@ ivcSize(const Indices& indices) const {
 
 template<typename RowIndices, typename ColIndices>
 struct valid_indexed_view_overload {
-  // Here we use is_convertible to Index instead of is_integral in order to treat enums as Index.
-  // In c++11 we could use is_integral<T> && is_enum<T> if is_convertible appears to be too permissive.
-  enum { value = !(internal::is_convertible<RowIndices,Index>::value && internal::is_convertible<ColIndices,Index>::value) };
+  enum { value = !(internal::is_valid_index_type<RowIndices>::value && internal::is_valid_index_type<ColIndices>::value) };
 };
 
 public:
@@ -146,7 +144,7 @@ operator()(const RowIndicesT (&rowIndices)[RowIndicesN], const ColIndicesT (&col
 
 template<typename Indices>
 typename internal::enable_if<
-  IsRowMajor && (!(internal::get_compile_time_incr<typename IvcType<Indices>::type>::value==1 || internal::is_integral<Indices>::value)),
+  IsRowMajor && (!(internal::get_compile_time_incr<typename IvcType<Indices>::type>::value==1 || internal::is_valid_index_type<Indices>::value)),
   IndexedView<EIGEN_INDEXED_VIEW_METHOD_CONST Derived,IvcIndex,typename IvcType<Indices>::type> >::type
 operator()(const Indices& indices) EIGEN_INDEXED_VIEW_METHOD_CONST
 {
@@ -157,7 +155,7 @@ operator()(const Indices& indices) EIGEN_INDEXED_VIEW_METHOD_CONST
 
 template<typename Indices>
 typename internal::enable_if<
-  (!IsRowMajor) && (!(internal::get_compile_time_incr<typename IvcType<Indices>::type>::value==1 || internal::is_integral<Indices>::value)),
+  (!IsRowMajor) && (!(internal::get_compile_time_incr<typename IvcType<Indices>::type>::value==1 || internal::is_valid_index_type<Indices>::value)),
   IndexedView<EIGEN_INDEXED_VIEW_METHOD_CONST Derived,typename IvcType<Indices>::type,IvcIndex> >::type
 operator()(const Indices& indices) EIGEN_INDEXED_VIEW_METHOD_CONST
 {
@@ -168,7 +166,7 @@ operator()(const Indices& indices) EIGEN_INDEXED_VIEW_METHOD_CONST
 
 template<typename Indices>
 typename internal::enable_if<
-  (internal::get_compile_time_incr<typename IvcType<Indices>::type>::value==1) && (!internal::is_integral<Indices>::value) && (!Symbolic::is_symbolic<Indices>::value),
+  (internal::get_compile_time_incr<typename IvcType<Indices>::type>::value==1) && (!internal::is_valid_index_type<Indices>::value) && (!Symbolic::is_symbolic<Indices>::value),
   VectorBlock<EIGEN_INDEXED_VIEW_METHOD_CONST Derived,internal::array_size<Indices>::value> >::type
 operator()(const Indices& indices) EIGEN_INDEXED_VIEW_METHOD_CONST
 {