Un-deprecate qSwap()

It seems to have fallen prey to the mass-deprecation of <QtAlgorithms>
in Qt 5.2. Since it didn't actually duplicate STL functionality, that
was uncalled-for: Unlike std::swap(), it's ADL-enabled, so the docs
were wrong to suggest replacing it with std::swap instead.

In fact, the tony-table that 5957f245c6c77c98d7e90d614c9fe2cdbfe7e8e6
added to qalgorithms.qdoc didn't include qSwap(), yet, qSwap() was
marked as deprecated.

Un-deprecate and expand the discussion to more faithfully represent
its value, without going into the depths of teaching how to swap
correctly in C++ (link to boost.org and cppreference.com for that
instead).

Remove the example that used qSwap() on doubles, which is precisely
_not_ how you should use it.

Amends 5957f245c6c77c98d7e90d614c9fe2cdbfe7e8e6(!).

[ChangeLog][QtCore] Un-deprecated qSwap().

Pick-to: 6.6 6.5 6.2 5.15
Change-Id: I4981005ba71b0d1824f2a46897145255fa66a7ea
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

1 files changed, 0 insertions, 9 deletions

diff --git a/src/corelib/doc/snippets/code/doc_src_qalgorithms.cpp b/src/corelib/doc/snippets/code/doc_src_qalgorithms.cpp
index 201517aa2a..f2b94a7416 100644
--- a/src/corelib/doc/snippets/code/doc_src_qalgorithms.cpp
+++ b/src/corelib/doc/snippets/code/doc_src_qalgorithms.cpp
@@ -1,15 +1,6 @@
 // Copyright (C) 2016 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
 
-//! [0]
-double pi = 3.14;
-double e = 2.71;
-
-qSwap(pi, e);
-// pi == 2.71, e == 3.14
-//! [0]
-
-
 //! [1]
 QList<Employee *> list;
 list.append(new Employee("Blackpool", "Stephen"));