From 6e389512f548d3efdb4f25407fb51e0cbbdc8051 Mon Sep 17 00:00:00 2001
From: Maxime Coste <mawww@kakoune.org>
Date: Fri, 26 May 2017 07:59:18 +0100
Subject: [PATCH] Modernize the way we compute memory domains from type

Use a constexpr function instead of a template type
---
 src/memory.hh | 12 +++++-------
 src/meta.hh   |  3 ++-
 src/vector.hh |  2 +-
 3 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/src/memory.hh b/src/memory.hh
index 4d41c0c0..fe6f70ea 100644
--- a/src/memory.hh
+++ b/src/memory.hh
@@ -6,6 +6,7 @@
 #include <utility>
 
 #include "assert.hh"
+#include "meta.hh"
 
 namespace Kakoune
 {
@@ -141,14 +142,11 @@ bool operator!=(const Allocator<T1, d1>& lhs, const Allocator<T2, d2>& rhs)
     return d1 != d2;
 }
 
+
+constexpr MemoryDomain memory_domain(Meta::AnyType) { return MemoryDomain::Undefined; }
+
 template<typename T>
-struct TypeDomain
-{
-    static constexpr MemoryDomain domain() { return TypeDomain<T>::helper((T*)nullptr); }
-private:
-    template<typename U> static decltype(U::Domain) constexpr helper(U*) { return U::Domain; }
-    static constexpr MemoryDomain helper(...) { return MemoryDomain::Undefined; }
-};
+constexpr decltype(T::Domain) memory_domain(Meta::Type<T>) { return T::Domain; }
 
 template<MemoryDomain d>
 struct UseMemoryDomain
diff --git a/src/meta.hh b/src/meta.hh
index 70a99428..04c343d5 100644
--- a/src/meta.hh
+++ b/src/meta.hh
@@ -6,7 +6,8 @@ namespace Kakoune
 inline namespace Meta
 {
 
-template<typename T> struct Type {};
+struct AnyType{};
+template<typename T> struct Type : AnyType {};
 
 }
 
diff --git a/src/vector.hh b/src/vector.hh
index c8cc9d08..e149998d 100644
--- a/src/vector.hh
+++ b/src/vector.hh
@@ -8,7 +8,7 @@
 namespace Kakoune
 {
 
-template<typename T, MemoryDomain domain = TypeDomain<T>::domain()>
+template<typename T, MemoryDomain domain = memory_domain(Meta::Type<T>{})>
 using Vector = std::vector<T, Allocator<T, domain>>;
 
 }