Loosen the requirements on the container passed to QtConcurrent::map*

Using std::begin() and std::end() forces the user to have const begin()
and end() member functions being defined for the passed container. This
is because std::declval<T>() returns rvalue which forces the compiler
to select std::{begin, end}()(const Container &c) overloads and an test
for a presence of const {begin, end}() methods.

Change-Id: I9d96d9f73891ece53224f1741a1334500f7b35ad
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/concurrent/qtconcurrentfunctionwrappers.h b/src/concurrent/qtconcurrentfunctionwrappers.h
index bb78ea9953..be95416759 100644
--- a/src/concurrent/qtconcurrentfunctionwrappers.h
+++ b/src/concurrent/qtconcurrentfunctionwrappers.h
@@ -77,7 +77,7 @@ struct Argument
 template <class Sequence>
 struct Argument<Sequence, typename std::enable_if<IsIterableValue<Sequence>>::type>
 {
-    using Type = std::decay_t<decltype(*std::begin(std::declval<Sequence>()))>;
+    using Type = std::decay_t<decltype(*std::declval<Sequence>().begin())>;
 };
 
 template <class Iterator>