diff options
author | Fabian Kosmale <fabian.kosmale@qt.io> | 2021-03-23 22:29:53 +0100 |
---|---|---|
committer | Fabian Kosmale <fabian.kosmale@qt.io> | 2021-03-25 11:22:29 +0100 |
commit | ce83e56cfeb2806181ec1daade9690f4c90b901c (patch) | |
tree | 11fb35a913320f8fb4ce7d007118bbe407e84c7a /src/corelib/global/qtypeinfo.h | |
parent | f1eccab04e01b3acc1a4b4c6a5fe7b3af3e2dcba (diff) |
QTypeInfo: Handle T::value_type being equal to T
Fix operator checks for containers whose value_type equals themselves.
It does not make sense to recurse on value_type in that case. Thanks to
std::disjunction having short-circuiting semantics, we can avoid that
issue by checking first whether T is T::value_type.
As a drive-by, check for value_type typedef before checking for
begin/end in is_container. This works around an issue in gcc <= 8.1,
which fails to correctly SFINAE the case where begin and end are private
methods.
Pick-to: 6.0 6.1
Fixes: QTBUG-89456
Change-Id: I27305a7cfe050f13a279c07f00bc229c01daa25b
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Diffstat (limited to 'src/corelib/global/qtypeinfo.h')
-rw-r--r-- | src/corelib/global/qtypeinfo.h | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/src/corelib/global/qtypeinfo.h b/src/corelib/global/qtypeinfo.h index 9b28958d33..58f20b7be4 100644 --- a/src/corelib/global/qtypeinfo.h +++ b/src/corelib/global/qtypeinfo.h @@ -228,8 +228,8 @@ template <typename, typename = void> struct is_container : std::false_type {}; template <typename T> struct is_container<T, std::void_t< - std::is_convertible<decltype(std::declval<T>().begin() != std::declval<T>().end()), bool>, - typename T::value_type + typename T::value_type, + std::is_convertible<decltype(std::declval<T>().begin() != std::declval<T>().end()), bool> >> : std::true_type {}; @@ -259,7 +259,11 @@ struct expand_operator_equal_container : expand_operator_equal_tuple<T> {}; // if T::value_type exists, check first T::value_type, then T itself template<typename T> struct expand_operator_equal_container<T, true> : - std::conjunction<expand_operator_equal<typename T::value_type>, expand_operator_equal_tuple<T>> {}; + std::conjunction< + std::disjunction< + std::is_same<T, typename T::value_type>, // avoid endless recursion + expand_operator_equal<typename T::value_type> + >, expand_operator_equal_tuple<T>> {}; // recursively check the template arguments of a tuple like object template<typename ...T> @@ -295,7 +299,12 @@ template<typename T, bool> struct expand_operator_less_than_container : expand_operator_less_than_tuple<T> {}; template<typename T> struct expand_operator_less_than_container<T, true> : - std::conjunction<expand_operator_less_than<typename T::value_type>, expand_operator_less_than_tuple<T>> {}; + std::conjunction< + std::disjunction< + std::is_same<T, typename T::value_type>, + expand_operator_less_than<typename T::value_type> + >, expand_operator_less_than_tuple<T> + > {}; template<typename ...T> using expand_operator_less_than_recursive = std::conjunction<expand_operator_less_than<T>...>; |