Adjust resize() behavior of QString and QByteArray to match Qt 5

resize() to a smaller size does not reallocate in Qt 5 if the container
is not shared. Match this here.

As a drive-by also fix resize calls on raw data strings to ensure
they are null terminated after the resize.

Change-Id: Ic4d8830e86ed3f247020d7ece3217cebd344ae96
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

2 files changed, 7 insertions, 25 deletions

diff --git a/src/corelib/text/qbytearray.cpp b/src/corelib/text/qbytearray.cpp
index f8c2759507..b85a46b146 100644
--- a/src/corelib/text/qbytearray.cpp
+++ b/src/corelib/text/qbytearray.cpp
@@ -1714,23 +1714,11 @@ void QByteArray::resize(int size)
     if (size < 0)
         size = 0;
 
-    if (!d->isShared() && !d->isMutable() && size < int(d.size)) {
-        d.size = size;
-        return;
-    }
-
-    if (size == 0 && !(d->flags() & Data::CapacityReserved)) {
-        d = DataPointer(Data::allocate(0), 0);
-    } else {
-        if (d->needsDetach() || size > capacity()
-                || (!(d->flags() & Data::CapacityReserved) && size < int(d.size)
-                    && size < (capacity() >> 1)))
-            reallocData(uint(size) + 1u, d->detachFlags() | Data::GrowsForward);
-        d.size = size;
-        if (d->isMutable()) {
-            d.data()[size] = '\0';
-        }
-    }
+    if (d->needsDetach() || size > capacity())
+        reallocData(uint(size) + 1u, d->detachFlags() | Data::GrowsForward);
+    d.size = size;
+    if (d->allocatedCapacity())
+        d.data()[size] = 0;
 }
 
 /*!
diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index 57be0eabcf..12b04b8ba7 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -2242,17 +2242,11 @@ void QString::resize(int size)
     if (size < 0)
         size = 0;
 
-    if (!d->isShared() && !d->isMutable() && size < int(d.size)) {
-        d.size = size;
-        return;
-    }
-
     if (d->needsDetach() || size > capacity())
         reallocData(uint(size) + 1u, true);
     d.size = size;
-    if (d->isMutable()) {
-        d.data()[size] = '\0';
-    }
+    if (d->allocatedCapacity())
+        d.data()[size] = 0;
 }
 
 /*!