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Document that qHash(T) must be in T's namespace, due to ADL

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Due to C++'s rule of Argument-Dependent Lookup, a call to an unqualified
qHash(t) will look up qHash in T's namespace. So edit the docs saying
that it must be "global qHash" to say that it should be in the type's
namespace.

Task-number: QTBUG-34912
Change-Id: I7a72800008ccb710b4bb814e42db7a95f385f53e
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
This commit is contained in:
Thiago Macieira 2014-07-22 16:08:22 -07:00
parent f07c27eec1
commit 8933d7c1f9
1 changed files with 4 additions and 4 deletions
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8
src/corelib/tools/qhash.cpp
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@ -986,8 +986,8 @@ uint qHash(long double key, uint seed) Q_DECL_NOTHROW
A QHash's key type has additional requirements other than being an
assignable data type: it must provide operator==(), and there must also be
a global qHash() function that returns a hash value for an argument of the
key's type.
a qHash() function in the type's namespace that returns a hash value for an
argument of the key's type.
The qHash() function computes a numeric value based on a key. It
can use any algorithm imaginable, as long as it always returns
@ -2152,8 +2152,8 @@ uint qHash(long double key, uint seed) Q_DECL_NOTHROW
QMultiHash's key and value data types must be \l{assignable data
types}. You cannot, for example, store a QWidget as a value;
instead, store a QWidget *. In addition, QMultiHash's key type
must provide operator==(), and there must also be a global
qHash() function that returns a hash value for an argument of the
must provide operator==(), and there must also be a qHash() function
in the type's namespace that returns a hash value for an argument of the
key's type. See the QHash documentation for details.
\sa QHash, QHashIterator, QMutableHashIterator, QMultiMap