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authorFabian Kosmale <fabian.kosmale@qt.io>2022-01-20 17:01:51 +0100
committerFabian Kosmale <fabian.kosmale@qt.io>2022-01-23 23:11:50 +0100
commit0842b01f0269cdd8099a5fbe849c5c2876a0d744 (patch)
tree3babb6f6cad2d8a27cc972c1d2a9f805c26c97cb /src
parent228b5dd0741512bfa3796c9388169cc12617b823 (diff)
QProperty: Work around constexpr issues on MSVC
MSVC complains about illegal uses of void, even though the code should be guarded by an if constexpr statement. qproperty.h(85): error C2182: 'val': illegal use of type 'void' qproperty.h(92): error C2182: 'abstract declarator': illegal use of type 'void' Avoid the issue by using a dedicated dummy type instead of void. Fixes: QTBUG-100072 Task-number: QTQAINFRA-4242 Pick-to: 6.3 6.2 Change-Id: Idc4886c26c3794e709eb762ba836139f720f8133 Reviewed-by: MÃ¥rten Nordheim <marten.nordheim@qt.io>
Diffstat (limited to 'src')
-rw-r--r--src/corelib/kernel/qpropertyprivate.h12
1 files changed, 9 insertions, 3 deletions
diff --git a/src/corelib/kernel/qpropertyprivate.h b/src/corelib/kernel/qpropertyprivate.h
index 8fe8cc7ff2..ddb09bb119 100644
--- a/src/corelib/kernel/qpropertyprivate.h
+++ b/src/corelib/kernel/qpropertyprivate.h
@@ -184,6 +184,12 @@ struct QPropertyProxyBindingData
namespace QtPrivate {
struct BindingEvaluationState;
+/* used in BindingFunctionVTable::createFor; on all other compilers, void would work, but on
+ MSVC this causes C2182 when compiling in C++20 mode. As we only need to provide some default
+ value which gets ignored, we introduce this dummy type.
+*/
+struct MSVCWorkAround {};
+
struct BindingFunctionVTable
{
using CallFn = bool(*)(QMetaType, QUntypedPropertyData *, void *);
@@ -194,7 +200,7 @@ struct BindingFunctionVTable
const MoveCtrFn moveConstruct;
const qsizetype size;
- template<typename Callable, typename PropertyType=void>
+ template<typename Callable, typename PropertyType=MSVCWorkAround>
static constexpr BindingFunctionVTable createFor()
{
static_assert (alignof(Callable) <= alignof(std::max_align_t), "Bindings do not support overaligned functors!");
@@ -205,7 +211,7 @@ struct BindingFunctionVTable
static_assert (std::is_invocable_r_v<bool, Callable, QMetaType, QUntypedPropertyData *> );
auto untypedEvaluationFunction = static_cast<Callable *>(f);
return std::invoke(*untypedEvaluationFunction, metaType, dataPtr);
- } else if constexpr (!std::is_same_v<PropertyType, void>) { // check for void to workaround MSVC issue
+ } else if constexpr (!std::is_same_v<PropertyType, MSVCWorkAround>) {
Q_UNUSED(metaType);
QPropertyData<PropertyType> *propertyPtr = static_cast<QPropertyData<PropertyType> *>(dataPtr);
// That is allowed by POSIX even if Callable is a function pointer
@@ -232,7 +238,7 @@ struct BindingFunctionVTable
}
};
-template<typename Callable, typename PropertyType=void>
+template<typename Callable, typename PropertyType=MSVCWorkAround>
inline constexpr BindingFunctionVTable bindingFunctionVTable = BindingFunctionVTable::createFor<Callable, PropertyType>();