Fix tensor casts for large packets and casts to/from std::complex

The original tensor casts were only defined for
`SrcCoeffRatio`:`TgtCoeffRatio` 1:1, 1:2, 2:1, 4:1. Here we add the
missing 1:N and 8:1.

We also add casting `Eigen::half` to/from `std::complex<T>`, which
was missing to make it consistent with `Eigen:bfloat16`, and
generalize the overload to work for any complex type.

Tests were added to `basicstuff`, `packetmath`, and
`cxx11_tensor_casts` to test all cast configurations.

1 files changed, 5 insertions, 12 deletions

diff --git a/Eigen/src/Core/arch/Default/BFloat16.h b/Eigen/src/Core/arch/Default/BFloat16.h
index c3725d473..99ce99a27 100644
--- a/Eigen/src/Core/arch/Default/BFloat16.h
+++ b/Eigen/src/Core/arch/Default/BFloat16.h
@@ -65,13 +65,8 @@ struct bfloat16 : public bfloat16_impl::bfloat16_base {
       : bfloat16_impl::bfloat16_base(bfloat16_impl::float_to_bfloat16_rtne(f)) {}
   // Following the convention of numpy, converting between complex and
   // float will lead to loss of imag value.
-  // Single precision complex.
-  typedef std::complex<float> complex64;
-  // Double precision complex.
-  typedef std::complex<double> complex128;
-  explicit EIGEN_DEVICE_FUNC bfloat16(const complex64& val)
-      : bfloat16_impl::bfloat16_base(bfloat16_impl::float_to_bfloat16_rtne(val.real())) {}
-  explicit EIGEN_DEVICE_FUNC bfloat16(const complex128& val)
+  template<typename RealScalar>
+  explicit EIGEN_DEVICE_FUNC bfloat16(const std::complex<RealScalar>& val)
       : bfloat16_impl::bfloat16_base(bfloat16_impl::float_to_bfloat16_rtne(static_cast<float>(val.real()))) {}
 
   EIGEN_DEVICE_FUNC EIGEN_EXPLICIT_CAST(bool) const {
@@ -114,11 +109,9 @@ struct bfloat16 : public bfloat16_impl::bfloat16_base {
   EIGEN_DEVICE_FUNC EIGEN_EXPLICIT_CAST(double) const {
     return static_cast<double>(bfloat16_impl::bfloat16_to_float(*this));
   }
-  EIGEN_DEVICE_FUNC EIGEN_EXPLICIT_CAST(complex64) const {
-    return complex64(bfloat16_impl::bfloat16_to_float(*this), float(0.0));
-  }
-  EIGEN_DEVICE_FUNC EIGEN_EXPLICIT_CAST(complex128) const {
-    return complex128(static_cast<double>(bfloat16_impl::bfloat16_to_float(*this)), double(0.0));
+  template<typename RealScalar>
+  EIGEN_DEVICE_FUNC EIGEN_EXPLICIT_CAST(std::complex<RealScalar>) const {
+    return std::complex<RealScalar>(static_cast<RealScalar>(bfloat16_impl::bfloat16_to_float(*this)), RealScalar(0));
   }
   EIGEN_DEVICE_FUNC EIGEN_EXPLICIT_CAST(Eigen::half) const {
     return static_cast<Eigen::half>(bfloat16_impl::bfloat16_to_float(*this));