From 77063418daf3d696df80af012a375daa47aca246 Mon Sep 17 00:00:00 2001
From: Michael Marshall <43034299+mmphys@users.noreply.github.com>
Date: Mon, 25 Jan 2021 15:09:36 +0000
Subject: [PATCH 1/2] Fix issue for GPU by ensuring accelerator_inline version
 of convertType is available for Grid::complex<T>. This removes many warnings
 in Hadrons Simplify the SFINAE syntax and correct convertType for iScalar

---
 Grid/lattice/Lattice_transfer.h | 39 +++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 16 deletions(-)

diff --git a/Grid/lattice/Lattice_transfer.h b/Grid/lattice/Lattice_transfer.h
index 91de721f..c91fa4d1 100644
--- a/Grid/lattice/Lattice_transfer.h
+++ b/Grid/lattice/Lattice_transfer.h
@@ -97,6 +97,21 @@ accelerator_inline void convertType(ComplexF & out, const std::complex<float> &
   out = in;
 }
 
+template<typename T>
+accelerator_inline typename std::enable_if<isGridFundamental<T>::value>::type
+convertType(T & out, const T & in) {
+  out = in;
+}
+
+// This would allow for conversions between GridFundamental types, but is not strictly needed as yet
+/*template<typename T1, typename T2>
+accelerator_inline typename std::enable_if<isGridFundamental<T1>::value && isGridFundamental<T2>::value>::type
+// Or to make this very broad, conversions between anything that's not a GridTensor could be allowed
+//accelerator_inline typename std::enable_if<!isGridTensor<T1>::value && !isGridTensor<T2>::value>::type
+convertType(T1 & out, const T2 & in) {
+  out = in;
+}*/
+
 #ifdef GRID_SIMT
 accelerator_inline void convertType(vComplexF & out, const ComplexF & in) {
   ((ComplexF*)&out)[acceleratorSIMTlane(vComplexF::Nsimd())] = in;
@@ -117,23 +132,20 @@ accelerator_inline void convertType(vComplexD2 & out, const vComplexF & in) {
   Optimization::PrecisionChange::StoD(in.v,out._internal[0].v,out._internal[1].v);
 }
 
-template<typename T1,typename T2,int N>
-  accelerator_inline void convertType(iMatrix<T1,N> & out, const iMatrix<T2,N> & in);
-template<typename T1,typename T2,int N>
-  accelerator_inline void convertType(iVector<T1,N> & out, const iVector<T2,N> & in);
-
-template<typename T1,typename T2, typename std::enable_if<!isGridScalar<T1>::value, T1>::type* = nullptr>
-accelerator_inline void convertType(T1 & out, const iScalar<T2> & in) {
-  convertType(out,in._internal);
+template<typename T1,typename T2>
+accelerator_inline void convertType(iScalar<T1> & out, const iScalar<T2> & in) {
+  convertType(out._internal,in._internal);
 }
 
-template<typename T1, typename std::enable_if<!isGridScalar<T1>::value, T1>::type* = nullptr>
-accelerator_inline void convertType(T1 & out, const iScalar<T1> & in) {
+template<typename T1,typename T2>
+accelerator_inline typename std::enable_if<!isGridScalar<T1>::value>::type
+convertType(T1 & out, const iScalar<T2> & in) {
   convertType(out,in._internal);
 }
 
 template<typename T1,typename T2>
-accelerator_inline void convertType(iScalar<T1> & out, const T2 & in) {
+accelerator_inline typename std::enable_if<!isGridScalar<T2>::value>::type
+convertType(iScalar<T1> & out, const T2 & in) {
   convertType(out._internal,in);
 }
 
@@ -150,11 +162,6 @@ accelerator_inline void convertType(iVector<T1,N> & out, const iVector<T2,N> & i
     convertType(out._internal[i],in._internal[i]);
 }
 
-template<typename T, typename std::enable_if<isGridFundamental<T>::value, T>::type* = nullptr>
-accelerator_inline void convertType(T & out, const T & in) {
-  out = in;
-}
-
 template<typename T1,typename T2>
 accelerator_inline void convertType(Lattice<T1> & out, const Lattice<T2> & in) {
   autoView( out_v , out,AcceleratorWrite);

From 3215d88a91214bc6bbed75cf21cf1a4a28b0bbfb Mon Sep 17 00:00:00 2001
From: Michael Marshall <43034299+mmphys@users.noreply.github.com>
Date: Wed, 3 Feb 2021 15:17:03 +0000
Subject: [PATCH 2/2] Simplify syntax with Grid::EnableIf post code review.
 Updated EnableIf so that ReturnType defaults to void in same way as
 std::enable_if see https://en.cppreference.com/w/cpp/types/enable_if

---
 Grid/lattice/Lattice_transfer.h | 9 +++------
 Grid/simd/Grid_vector_types.h   | 4 ++--
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/Grid/lattice/Lattice_transfer.h b/Grid/lattice/Lattice_transfer.h
index c91fa4d1..5a26cce9 100644
--- a/Grid/lattice/Lattice_transfer.h
+++ b/Grid/lattice/Lattice_transfer.h
@@ -98,8 +98,7 @@ accelerator_inline void convertType(ComplexF & out, const std::complex<float> &
 }
 
 template<typename T>
-accelerator_inline typename std::enable_if<isGridFundamental<T>::value>::type
-convertType(T & out, const T & in) {
+accelerator_inline EnableIf<isGridFundamental<T>> convertType(T & out, const T & in) {
   out = in;
 }
 
@@ -138,14 +137,12 @@ accelerator_inline void convertType(iScalar<T1> & out, const iScalar<T2> & in) {
 }
 
 template<typename T1,typename T2>
-accelerator_inline typename std::enable_if<!isGridScalar<T1>::value>::type
-convertType(T1 & out, const iScalar<T2> & in) {
+accelerator_inline NotEnableIf<isGridScalar<T1>> convertType(T1 & out, const iScalar<T2> & in) {
   convertType(out,in._internal);
 }
 
 template<typename T1,typename T2>
-accelerator_inline typename std::enable_if<!isGridScalar<T2>::value>::type
-convertType(iScalar<T1> & out, const T2 & in) {
+accelerator_inline NotEnableIf<isGridScalar<T2>> convertType(iScalar<T1> & out, const T2 & in) {
   convertType(out._internal,in);
 }
 
diff --git a/Grid/simd/Grid_vector_types.h b/Grid/simd/Grid_vector_types.h
index c07077a3..4f952bb2 100644
--- a/Grid/simd/Grid_vector_types.h
+++ b/Grid/simd/Grid_vector_types.h
@@ -208,8 +208,8 @@ struct RealPart<complex<T> > {
 //////////////////////////////////////
 // type alias used to simplify the syntax of std::enable_if
 template <typename T> using Invoke = typename T::type;
-template <typename Condition, typename ReturnType> using EnableIf    = Invoke<std::enable_if<Condition::value, ReturnType> >;
-template <typename Condition, typename ReturnType> using NotEnableIf = Invoke<std::enable_if<!Condition::value, ReturnType> >;
+template <typename Condition, typename ReturnType = void> using EnableIf    = Invoke<std::enable_if<Condition::value, ReturnType> >;
+template <typename Condition, typename ReturnType = void> using NotEnableIf = Invoke<std::enable_if<!Condition::value, ReturnType> >;
 
 ////////////////////////////////////////////////////////
 // Check for complexity with type traits