From 85b7479cb16c0019f76e33cca87fd2a2e95c6a5e Mon Sep 17 00:00:00 2001
From: Fabian Knorr <fabian.knorr@dps.uibk.ac.at>
Date: Thu, 3 Aug 2023 14:15:30 +0200
Subject: [PATCH] Remove subscript_result_t workaround

---
 include/accessor.h | 12 ++++++------
 include/fence.h    |  2 +-
 include/ranges.h   | 21 +++------------------
 3 files changed, 10 insertions(+), 25 deletions(-)

diff --git a/include/accessor.h b/include/accessor.h
index 36c7a24db..e4d26a801 100644
--- a/include/accessor.h
+++ b/include/accessor.h
@@ -201,8 +201,8 @@ class accessor<DataT, Dims, Mode, target::device> : public detail::accessor_base
 		return m_device_ptr[get_linear_offset(index)];
 	}
 
-	template <int D = Dims>
-	inline std::enable_if_t<(D > 0), detail::subscript_result_t<D, const accessor>> operator[](const size_t index) const {
+	template <int D = Dims, std::enable_if_t<(D > 0), int> = 0>
+	inline decltype(auto) operator[](const size_t index) const {
 		return detail::subscript<D>(*this, index);
 	}
 
@@ -415,8 +415,8 @@ class accessor<DataT, Dims, Mode, target::host_task> : public detail::accessor_b
 		return m_host_ptr[get_linear_offset(index)];
 	}
 
-	template <int D = Dims>
-	inline std::enable_if_t<(D > 0), detail::subscript_result_t<D, const accessor>> operator[](const size_t index) const {
+	template <int D = Dims, std::enable_if_t<(D > 0), int> = 0>
+	inline decltype(auto) operator[](const size_t index) const {
 		return detail::subscript<D>(*this, index);
 	}
 
@@ -666,8 +666,8 @@ class local_accessor {
 		}
 	}
 
-	template <int D = Dims>
-	inline std::enable_if_t<(D > 0), detail::subscript_result_t<Dims, const local_accessor>> operator[](const size_t dim0) const {
+	template <int D = Dims, std::enable_if_t<(D > 0), int> = 0>
+	inline decltype(auto) operator[](const size_t dim0) const {
 		return detail::subscript<Dims>(*this, dim0);
 	}
 
diff --git a/include/fence.h b/include/fence.h
index 35fc5d831..5c3e48259 100644
--- a/include/fence.h
+++ b/include/fence.h
@@ -46,7 +46,7 @@ class buffer_snapshot {
 	inline const T& operator[](const id<Dims> index) const { return m_data[detail::get_linear_index(m_subrange.range, index)]; }
 
 	template <int D = Dims, std::enable_if_t<(D > 0), int> = 0>
-	inline detail::subscript_result_t<Dims, const buffer_snapshot> operator[](const size_t index) const {
+	inline decltype(auto) operator[](const size_t index) const {
 		return detail::subscript<Dims>(*this, index);
 	}
 
diff --git a/include/ranges.h b/include/ranges.h
index 3b91ad132..1a4ff383a 100644
--- a/include/ranges.h
+++ b/include/ranges.h
@@ -401,23 +401,8 @@ namespace detail {
 	template <int TargetDims, typename Target, int SubscriptDim = 0>
 	class subscript_proxy;
 
-	template <int TargetDims, typename Target, int SubscriptDim = 0>
-	struct subscript_result {
-		using type = subscript_proxy<TargetDims, Target, SubscriptDim + 1>;
-	};
-
-	template <int TargetDims, typename Target>
-	struct subscript_result<TargetDims, Target, TargetDims - 1> {
-		using type = decltype(std::declval<Target&>()[std::declval<const id<TargetDims>&>()]);
-	};
-
-	// Workaround for old ComputeCpp "stable" compiler: We cannot use decltype(auto), because it will not infer lvalue references correctly
-	// TODO replace subscript_result and all its uses with decltype(auto) once we require the new ComputeCpp (experimental) compiler.
-	template <int TargetDims, typename Target, int SubscriptDim = 0>
-	using subscript_result_t = typename subscript_result<TargetDims, Target, SubscriptDim>::type;
-
 	template <int TargetDims, typename Target, int SubscriptDim>
-	inline subscript_result_t<TargetDims, Target, SubscriptDim> subscript(Target& tgt, id<TargetDims> id, const size_t index) {
+	inline decltype(auto) subscript(Target& tgt, id<TargetDims> id, const size_t index) {
 		static_assert(SubscriptDim < TargetDims);
 		id[SubscriptDim] = index;
 		if constexpr(SubscriptDim == TargetDims - 1) {
@@ -428,7 +413,7 @@ namespace detail {
 	}
 
 	template <int TargetDims, typename Target>
-	inline subscript_result_t<TargetDims, Target> subscript(Target& tgt, const size_t index) {
+	inline decltype(auto) subscript(Target& tgt, const size_t index) {
 		return subscript<TargetDims, Target, 0>(tgt, id<TargetDims>{}, index);
 	}
 
@@ -437,7 +422,7 @@ namespace detail {
 	  public:
 		subscript_proxy(Target& tgt, const id<TargetDims> id) : m_tgt(tgt), m_id(id) {}
 
-		inline subscript_result_t<TargetDims, Target, SubscriptDim> operator[](const size_t index) const {
+		inline decltype(auto) operator[](const size_t index) const {
 			return subscript<TargetDims, Target, SubscriptDim>(m_tgt, m_id, index);
 		}