Introduce the Mutable flag and move QArrayDataPointer::needsDetach

The Mutable flag now contains the information on whether the data this
QArrayData points to is mutable. This decouples the mutability /
immutability setting from the allocation and from the type of data,
opening the way for mutable raw or foreign data.

There are still plenty of places in the source code that check the
size of the allocation when it actually wants d->isMutable(). Fixing
this will require reviewing all the code, so is left for later.

The needsDetach() function is moved to QArrayData and
de-constified. It returns true when a reallocation is necessary if the
data is to be modified.

Change-Id: I17e2bc5a3f6ef1f3eba8a205acd9852b95524f57
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/corelib/tools/qarraydata.cpp b/src/corelib/tools/qarraydata.cpp
index bc48619349..3123d7467f 100644
--- a/src/corelib/tools/qarraydata.cpp
+++ b/src/corelib/tools/qarraydata.cpp
@@ -222,7 +222,7 @@ QArrayData *QArrayData::allocate(size_t objectSize, size_t alignment,
         return nullptr;
 
     size_t allocSize = calculateBlockSize(capacity, objectSize, headerSize, options);
-    options |= ArrayOption(AllocatedDataType);
+    options |= AllocatedDataType | Mutable;
     QArrayData *header = allocateData(allocSize, options);
     if (header) {
         quintptr data = (quintptr(header) + sizeof(QArrayData) + alignment - 1)
@@ -252,6 +252,7 @@ QArrayData *QArrayData::reallocateUnaligned(QArrayData *data, size_t objectSize,
     options |= ArrayOption(AllocatedDataType);
     size_t headerSize = sizeof(QArrayData);
     size_t allocSize = calculateBlockSize(capacity, objectSize, headerSize, options);
+    options |= AllocatedDataType | Mutable;
     QArrayData *header = reallocateData(data, allocSize, options);
     if (header)
         header->alloc = capacity;