path: root/src/testlib
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authorGiuseppe D'Angelo <>2020-02-15 00:11:22 +0100
committerGiuseppe D'Angelo <>2020-06-10 16:49:08 +0200
commit8e98a161e993c6636d217276a0f2373d642ff050 (patch)
tree23adce823bfab9795cf7b775d35f14be7baedc10 /src/testlib
parentce5931aaf2c9698925366e787d08747a1c60c378 (diff)
Long live std::pair!
Make QPair an alias for std::pair, and qMakePair just a forwarder towards std::make_pair. Why? Fundamentally to ditch a bunch of NIH code; gain for free structured bindings, std::tuple and std::reference_wrapper compatibility, and so on. Breakages: * Some that code manually forward declares QPair. We don't care about it (<QContainerFwd> is the proper way). * Some code that overloads on std::pair and QPair. Luckily it's mostly centralized: debug, metatypes, testing macros. Just remove the QPair overload. * Usages of qMakePair forcing the template type parameters. There are a handful of these in qtbase, but only one was actually broken. * std::pair is NOT (and will never likely be) trivially copiable. This is agreed to be a mistake done by practically all implementations in C++11, can can't be fixed without breaking ABI. Some code using QPair assuming it's trivially copiable may break; exactly one occurrence was in qtbase. * QMetaType logic extracts the type names in two different ways, one by looking at the source code string (e.g. extracted by moc) and one via some ad-hoc reflection in C++. We need to make "QPair" (as spelled in the source code) be the same as "std::pair" (gathered via reflection, which will see through the alias) when compared. The way it's already done e.g. for QList is by actually replacing the moc-extracted name with the name of the actual type used in C++; do the same here. On libc++, std::pair is actually in an inline namespace -- i.e. std::__1::pair; the reflection will extract and store "std::__1::pair" so we need an ad-hoc fix to QMetaType. [ChangeLog][QtCore][QPair] QPair is now an alias to std::pair, and does not exist as a class in Qt any more. This may break code such as functions overloaded for both QPair and std::pair. Usually, the overload taking a QPair can be safely discarded, leaving only the one taking a std::pair. QPair API has not changed, and qMakePair is still available for compatibility (although new code is encouraged to use std::pair and std::make_pair directly instead). Change-Id: I7725c751bf23946cde577b1406e86a336c0a3dcf Reviewed-by: Lars Knoll <>
Diffstat (limited to 'src/testlib')
1 files changed, 0 insertions, 8 deletions
diff --git a/src/testlib/qtest.h b/src/testlib/qtest.h
index 18175196ff..9455a66fdd 100644
--- a/src/testlib/qtest.h
+++ b/src/testlib/qtest.h
@@ -232,14 +232,6 @@ template<> inline char *toString(const QVariant &v)
template <typename T1, typename T2>
-inline char *toString(const QPair<T1, T2> &pair)
- const QScopedArrayPointer<char> first(toString(pair.first));
- const QScopedArrayPointer<char> second(toString(pair.second));
- return toString(QString::asprintf("QPair(%s,%s)",,;
-template <typename T1, typename T2>
inline char *toString(const std::pair<T1, T2> &pair)
const QScopedArrayPointer<char> first(toString(pair.first));