From cf7e2e277f76d965fe37dac5a3fecf588f58e3b7 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Sun, 17 Mar 2019 21:59:30 +0100
Subject: bug #1692: enable enum as sizes of Matrix and Array

---
 Eigen/src/Core/PlainObjectBase.h | 12 +++++++-----
 test/constructor.cpp             | 13 +++++++++++++
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/Eigen/src/Core/PlainObjectBase.h b/Eigen/src/Core/PlainObjectBase.h
index 4dbc40e5b..6de78fd2f 100644
--- a/Eigen/src/Core/PlainObjectBase.h
+++ b/Eigen/src/Core/PlainObjectBase.h
@@ -802,8 +802,10 @@ class PlainObjectBase : public internal::dense_xpr_base<Derived>::type
     EIGEN_DEVICE_FUNC
     EIGEN_STRONG_INLINE void _init2(Index rows, Index cols, typename internal::enable_if<Base::SizeAtCompileTime!=2,T0>::type* = 0)
     {
-      EIGEN_STATIC_ASSERT(bool(NumTraits<T0>::IsInteger) &&
-                          bool(NumTraits<T1>::IsInteger),
+      const bool t0_is_integer_alike = internal::is_valid_index_type<T0>::value;
+      const bool t1_is_integer_alike = internal::is_valid_index_type<T1>::value;
+      EIGEN_STATIC_ASSERT(t0_is_integer_alike &&
+                          t1_is_integer_alike,
                           FLOATING_POINT_ARGUMENT_PASSED__INTEGER_WAS_EXPECTED)
       resize(rows,cols);
     }
@@ -838,9 +840,9 @@ class PlainObjectBase : public internal::dense_xpr_base<Derived>::type
                                                                               && ((!internal::is_same<typename internal::traits<Derived>::XprKind,ArrayXpr>::value || Base::SizeAtCompileTime==Dynamic)),T>::type* = 0)
     {
       // NOTE MSVC 2008 complains if we directly put bool(NumTraits<T>::IsInteger) as the EIGEN_STATIC_ASSERT argument.
-      const bool is_integer = NumTraits<T>::IsInteger;
-      EIGEN_UNUSED_VARIABLE(is_integer);
-      EIGEN_STATIC_ASSERT(is_integer,
+      const bool is_integer_alike = internal::is_valid_index_type<T>::value;
+      EIGEN_UNUSED_VARIABLE(is_integer_alike);
+      EIGEN_STATIC_ASSERT(is_integer_alike,
                           FLOATING_POINT_ARGUMENT_PASSED__INTEGER_WAS_EXPECTED)
       resize(size);
     }
diff --git a/test/constructor.cpp b/test/constructor.cpp
index 1dd3bc3c0..e793dfca1 100644
--- a/test/constructor.cpp
+++ b/test/constructor.cpp
@@ -81,4 +81,17 @@ EIGEN_DECLARE_TEST(constructor)
     Array<float,3,3> a(123);
     VERIFY_IS_EQUAL(a(4), 123.f);
   }
+  {
+    enum { M = 12, N = 7};
+    MatrixXi m1(M,N);
+    VERIFY_IS_EQUAL(m1.rows(),M);
+    VERIFY_IS_EQUAL(m1.cols(),N);
+    ArrayXXi a1(M,N);
+    VERIFY_IS_EQUAL(a1.rows(),M);
+    VERIFY_IS_EQUAL(a1.cols(),N);
+    VectorXi v1(M);
+    VERIFY_IS_EQUAL(v1.size(),M);
+    ArrayXi a2(M);
+    VERIFY_IS_EQUAL(a2.size(),M);
+  }
 }
-- 
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