From 38b91f256be8bf498f0ba9e8dc4fa0abdd7abe70 Mon Sep 17 00:00:00 2001
From: David Tellenbach <david.tellenbach@me.com>
Date: Wed, 22 Jul 2020 17:56:15 +0200
Subject: [PATCH] Fix cast of blfoat16 to std::complex<T>

This fixes https://gitlab.com/libeigen/eigen/-/issues/1951
---
 Eigen/src/Core/arch/Default/BFloat16.h | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/Eigen/src/Core/arch/Default/BFloat16.h b/Eigen/src/Core/arch/Default/BFloat16.h
index 3ea725d9b..f9c6e76a9 100644
--- a/Eigen/src/Core/arch/Default/BFloat16.h
+++ b/Eigen/src/Core/arch/Default/BFloat16.h
@@ -34,9 +34,8 @@ namespace Eigen {
 
 struct bfloat16;
 
-// explicit conversion operators are no available before C++11 so we first cast
-// bfloat16 to RealScalar rather than to std::complex<RealScalar> directly
-#if !EIGEN_HAS_CXX11
+// Since we allow implicit conversion of bfloat16 to float and double, we
+// need to make the cast to complex a bit more explicit
 namespace internal {
 template <typename RealScalar>
 struct cast_impl<bfloat16, std::complex<RealScalar> > {
@@ -46,7 +45,6 @@ struct cast_impl<bfloat16, std::complex<RealScalar> > {
   }
 };
 } // namespace internal
-#endif  // EIGEN_HAS_CXX11
 
 namespace bfloat16_impl {