--- blender-2.91.0/extern/Eigen3/Eigen/src/Core/MathFunctions.h.ifelse	2020-02-17 19:00:06.000000000 +0900
+++ blender-2.91.0/extern/Eigen3/Eigen/src/Core/MathFunctions.h	2021-01-18 23:04:43.551976542 +0900
@@ -482,8 +482,9 @@ struct log1p_impl {
     EIGEN_STATIC_ASSERT_NON_INTEGER(Scalar)
     #if EIGEN_HAS_CXX11_MATH
     using std::log1p;
-    #endif
+    #else
     using std_fallback::log1p;
+    #endif
     return log1p(x);
   }
 };