whytofly
/
qt6-bb10
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

qtypeinfo: Improve container check 

Smart pointers like QSharedPointer<T> do have a value_type, but their
equality does not depend on T being comparable. Therefore, instead of
simply checking for T::value_type, test for a few other container
requirements.
This also required to add an additional check for std::optional, as that
one has an unconstrained operator== on MSVC.

Change-Id: Iefd048f7aa360f4713ecd79f80acd7dae72ee18c
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
bb10
Fabian Kosmale 2020-07-12 11:17:21 +02:00
parent 8cdaeb2655
commit ca54b741d6
2 changed files with 22 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
src/corelib/global/qtypeinfo.h
View File

@ -41,6 +41,7 @@
#include <QtCore/qglobal.h>
#include <QtCore/qcontainerfwd.h>
#include <variant>
#include <optional>
#ifndef QTYPEINFO_H
#define QTYPEINFO_H
@ -342,12 +343,16 @@ namespace QTypeTraits
*/
namespace detail {
// find out whether T has a value_type typedef
// find out whether T is a conteiner
// this is required to check the value type of containers for the existence of the comparison operator
template <typename, typename = void>
struct has_value_type : std::false_type {};
struct is_container : std::false_type {};
template <typename T>
struct has_value_type<T, std::void_t<typename T::value_type>> : std::true_type {};
struct is_container<T, std::void_t<
std::is_convertible<decltype(std::declval<T>().begin() != std::declval<T>().end()), bool>,
typename T::value_type
>> : std::true_type {};
// Checks the existence of the comparison operator for the class itself
template <typename, typename = void>
@ -357,7 +362,7 @@ struct has_operator_equal<T, std::void_t<decltype(bool(std::declval<const T&>()
: std::true_type {};
// Two forward declarations
template<typename T, bool = has_value_type<T>::value>
template<typename T, bool = is_container<T>::value>
struct expand_operator_equal_container;
template<typename T>
struct expand_operator_equal_tuple;
@ -366,7 +371,7 @@ struct expand_operator_equal_tuple;
template<typename T>
using expand_operator_equal = expand_operator_equal_container<T>;
// if T doesn't have a value_type member check if it's a tuple like object
// if T isn't a container check if it's a tuple like object
template<typename T, bool>
struct expand_operator_equal_container : expand_operator_equal_tuple<T> {};
// if T::value_type exists, check first T::value_type, then T itself
@ -380,6 +385,8 @@ using expand_operator_equal_recursive = std::conjunction<expand_operator_equal<T
template<typename T>
struct expand_operator_equal_tuple : has_operator_equal<T> {};
template<typename T>
struct expand_operator_equal_tuple<std::optional<T>> : has_operator_equal<T> {};
template<typename T1, typename T2>
struct expand_operator_equal_tuple<std::pair<T1, T2>> : expand_operator_equal_recursive<T1, T2> {};
template<typename ...T>
@ -394,7 +401,7 @@ template <typename T>
struct has_operator_less_than<T, std::void_t<decltype(bool(std::declval<const T&>() < std::declval<const T&>()))>>
: std::true_type{};
template<typename T, bool = has_value_type<T>::value>
template<typename T, bool = is_container<T>::value>
struct expand_operator_less_than_container;
template<typename T>
struct expand_operator_less_than_tuple;

9
tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp
View File

@ -101,6 +101,11 @@ static_assert(!QTypeTraits::has_operator_less_than_v<QHash<int, QString>>);
static_assert(!QTypeTraits::has_operator_equal_v<QHash<int, NoOperators>>);
static_assert(!QTypeTraits::has_operator_less_than_v<QHash<int, NoOperators>>);
// QSharedPointer
static_assert(QTypeTraits::has_operator_equal_v<QSharedPointer<QString>>);
// smart pointer equality doesn't depend on T
static_assert(QTypeTraits::has_operator_equal_v<QSharedPointer<NoOperators>>);
// std::vector
static_assert(QTypeTraits::has_operator_equal_v<std::vector<QString>>);
static_assert(QTypeTraits::has_operator_less_than_v<std::vector<QString>>);
@ -127,6 +132,10 @@ static_assert(QTypeTraits::has_operator_less_than_v<std::map<int, QString>>);
static_assert(!QTypeTraits::has_operator_equal_v<std::map<int, NoOperators>>);
static_assert(!QTypeTraits::has_operator_less_than_v<std::map<int, NoOperators>>);
// std::optional
static_assert(QTypeTraits::has_operator_equal_v<std::optional<QString>>);
static_assert(!QTypeTraits::has_operator_equal_v<std::optional<NoOperators>>);
// nested types
static_assert(QTypeTraits::has_operator_equal_v<Nested>);
static_assert(!QTypeTraits::has_operator_less_than_v<Nested>);