Unify all mid() functions in QtBase.

Up to now, Qt had at least 3 different implementations of the mid().
Only QString::mid implementation was not crashing on edge cases and
was protected against overflows, therefore I picked that one as the
base implementation, even if it has weird semantics for an invalid
input.

As a side effect QVector::mid was slightly optimized to not detach in
all cases (which follows current QList behavior). Documentation of
QVector::mid and QList::mid was updated to not mention "copy of data"
which could suggest that the mid() result is detached.

QStringRef::mid was fixed and now it follows general Qt behavior, by
returning a null value for a null input.

Change-Id: Ie9ff5d98372bd193d66508e6dd92b6ed1180ad9b
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/corelib/tools/qlist.cpp b/src/corelib/tools/qlist.cpp
index 0811c3793e..db49fe9802 100644
--- a/src/corelib/tools/qlist.cpp
+++ b/src/corelib/tools/qlist.cpp
@@ -491,11 +491,11 @@ void **QListData::erase(void **xi)
 /*!
     \fn QList<T> QList<T>::mid(int pos, int length) const
 
-    Returns a list whose elements are copied from this list,
+    Returns a sub-list which includes elements from this list,
     starting at position \a pos. If \a length is -1 (the default), all
-    elements from \a pos are copied; otherwise \a length elements (or
+    elements from \a pos are included; otherwise \a length elements (or
     all remaining elements if there are less than \a length elements)
-    are copied.
+    are included.
 */
 
 /*! \fn QList::QList()