From d1274da76615f5cc5fcc489eee2421a2d64d3a9b Mon Sep 17 00:00:00 2001
From: David Feltell <dave@feltell.net>
Date: Sat, 30 May 2020 19:50:28 +0100
Subject: [PATCH] Support assignment from `TensorMap` wrapping a `const` type
 to a `Tensor` storing non-`const`

* Add test that copy-assigns to a `Tensor` from a `TensorMap` wrapping an array of `const`-qualified data.
* Missing inline declaration for a `maskstore` overload causing "multiple definition of `Fastor::maskstore`" errors.
* Use destination type (i.e. non-const) to construct `SIMDVector` in `eval` functions, otherwise we get "assignment of read-only location" errors.
* Don't `const`-qualify destination tensor in `assign`, otherwise overload resolution of called `trivial_assign` fails.
---
 Fastor/simd_vector/simd_vector_common.h |  2 ++
 Fastor/tensor/TensorEvaluator.h         | 12 ++++++------
 Fastor/tensor/TensorMap.h               |  2 +-
 tests/test_tensormap/test_tensormap.cpp | 10 ++++++++++
 4 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/Fastor/simd_vector/simd_vector_common.h b/Fastor/simd_vector/simd_vector_common.h
index c3c4e7a..1522f1f 100644
--- a/Fastor/simd_vector/simd_vector_common.h
+++ b/Fastor/simd_vector/simd_vector_common.h
@@ -599,6 +599,8 @@ void maskstore(std::complex<double> * FASTOR_RESTRICT a, const int (&maska)[4],
     _mm256_maskstore_pd(reinterpret_cast<double*>(a  ), (__m256i) mask0, lo);
     _mm256_maskstore_pd(reinterpret_cast<double*>(a+2), (__m256i) mask1, hi);
 }
+template<>
+FASTOR_INLINE
 void maskstore(std::complex<float> * FASTOR_RESTRICT a, const int (&maska)[8], SIMDVector<std::complex<float>,simd_abi::avx> &v) {
     // Split the mask in to a higher and lower part - we need two masks for this
     __m256i mask0 = _mm256_set_epi32(maska[4],maska[4],maska[5],maska[5],maska[6],maska[6],maska[7],maska[7]);
diff --git a/Fastor/tensor/TensorEvaluator.h b/Fastor/tensor/TensorEvaluator.h
index 54ecabe..27bc8d1 100644
--- a/Fastor/tensor/TensorEvaluator.h
+++ b/Fastor/tensor/TensorEvaluator.h
@@ -4,8 +4,8 @@
 // Expression templates evaluators
 //----------------------------------------------------------------------------------------------------------//
 template<typename U=T>
-FASTOR_INLINE SIMDVector<T,simd_abi_type> eval(FASTOR_INDEX i) const {
-    SIMDVector<T,simd_abi_type> _vec;
+FASTOR_INLINE SIMDVector<U,simd_abi_type> eval(FASTOR_INDEX i) const {
+    SIMDVector<U,simd_abi_type> _vec;
     _vec.load(&_data[get_mem_index(i)],false);
     return _vec;
 }
@@ -14,8 +14,8 @@ FASTOR_INLINE T eval_s(FASTOR_INDEX i) const {
     return _data[get_mem_index(i)];
 }
 template<typename U=T>
-FASTOR_INLINE SIMDVector<T,simd_abi_type> eval(FASTOR_INDEX i, FASTOR_INDEX j) const {
-    SIMDVector<T,simd_abi_type> _vec;
+FASTOR_INLINE SIMDVector<U,simd_abi_type> eval(FASTOR_INDEX i, FASTOR_INDEX j) const {
+    SIMDVector<U,simd_abi_type> _vec;
     _vec.load(&_data[get_flat_index(i,j)],false);
     return _vec;
 }
@@ -25,8 +25,8 @@ FASTOR_INLINE T eval_s(FASTOR_INDEX i, FASTOR_INDEX j) const {
 }
 
 template<typename U=T>
-FASTOR_INLINE SIMDVector<T,simd_abi_type> teval(const std::array<int, dimension_t::value> &as) const {
-    SIMDVector<T,simd_abi_type> _vec;
+FASTOR_INLINE SIMDVector<U,simd_abi_type> teval(const std::array<int, dimension_t::value> &as) const {
+    SIMDVector<U,simd_abi_type> _vec;
     _vec.load(&_data[get_flat_index(as)],false);
     return _vec;
 }
diff --git a/Fastor/tensor/TensorMap.h b/Fastor/tensor/TensorMap.h
index 509358e..9215a48 100644
--- a/Fastor/tensor/TensorMap.h
+++ b/Fastor/tensor/TensorMap.h
@@ -143,7 +143,7 @@ FASTOR_MAKE_OS_STREAM_TENSORn(TensorMap)
 
 
 template<typename Derived, size_t DIM, typename T, size_t ...Rest>
-FASTOR_INLINE void assign(const AbstractTensor<Derived,DIM> &dst, const TensorMap<T,Rest...> &src) {
+FASTOR_INLINE void assign(AbstractTensor<Derived,DIM> &dst, const TensorMap<T,Rest...> &src) {
     if (dst.self().data()==src.data()) return;
     trivial_assign(dst.self(),src);
 }
diff --git a/tests/test_tensormap/test_tensormap.cpp b/tests/test_tensormap/test_tensormap.cpp
index 64e05a0..1fe5542 100644
--- a/tests/test_tensormap/test_tensormap.cpp
+++ b/tests/test_tensormap/test_tensormap.cpp
@@ -55,6 +55,16 @@ void run() {
         FASTOR_EXIT_ASSERT(abs(a.sum() - ma.sum()) < Tol);
     }
 
+    // Map a const array and copy-assign it to a non-const tensor.
+    {
+        const T data[] = {1, 2, 3};
+        TensorMap<const T, 3> mdata{data};
+        Tensor<T, 3> tdata = mdata;
+        Tensor<T, 3> check{1, 2, 3};
+
+        FASTOR_EXIT_ASSERT(all_of(tdata == check));
+    }
+
     print(FGRN(BOLD("All tests passed successfully")));
 }