Utils: Don't allocate new memory if it is fitting in the short string

If you call reserve on a read only reference we always allocated on the
heap which is not that smart.

Change-Id: Ib9653c6fc87bc65716a966545c13f7ecb3712039
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/libs/utils/smallstring.h b/src/libs/utils/smallstring.h
index df17b7f30c..6c489c01d8 100644
--- a/src/libs/utils/smallstring.h
+++ b/src/libs/utils/smallstring.h
@@ -258,6 +258,8 @@ public:
                 m_data.allocated.data.pointer = Memory::reallocate(m_data.allocated.data.pointer,
                                                                newCapacity + 1);
                 m_data.allocated.data.capacity = newCapacity;
+            } else if (newCapacity <= shortStringCapacity()) {
+                new (this) BasicSmallString{m_data.allocated.data.pointer, m_data.allocated.data.size};
             } else {
                 const size_type oldSize = size();
                 newCapacity = std::max(newCapacity, oldSize);