QString: don't detach in remove(pos, len)

- If this string isn't shared, don't call detach, instead use ->erase() as
  needed
- If this string is shared, create a new string, and copy all elements
  except the ones that would be removed, see task for details

Update unittest to test both code paths.

Task-number: QTBUG-106181
Change-Id: I4c73ff17a6fa89ddcf6966f9c5bf789753f6d39e
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 16 insertions, 6 deletions

diff --git a/tests/auto/corelib/text/qstring/tst_qstring.cpp b/tests/auto/corelib/text/qstring/tst_qstring.cpp
index 80bc6c9208..0462d0689d 100644
--- a/tests/auto/corelib/text/qstring/tst_qstring.cpp
+++ b/tests/auto/corelib/text/qstring/tst_qstring.cpp
@@ -3318,13 +3318,23 @@ void tst_QString::remove_uint_uint()
     QFETCH( int, index );
     QFETCH( int, len );
     QFETCH( QString, after );
+    QFETCH(QString, result);
 
-    if ( after.size() == 0 ) {
-        QString s1 = string;
-        s1.remove( (uint) index, (uint) len );
-        QTEST( s1, "result" );
-    } else
-        QCOMPARE( 0, 0 ); // shut Qt Test
+    // For the replace() unitests?
+    if ( after.size() != 0 ) {
+        return;
+    }
+
+    // Test when isShared() is true
+    QString s1 = string;
+    s1.remove((qsizetype)index, (qsizetype)len);
+    QCOMPARE(s1, result);
+
+    QString s2 = string;
+    // Test when isShared() is false
+    s2.detach();
+    s2.remove((qsizetype)index, (qsizetype)len);
+    QCOMPARE(s2, result);
 }
 
 void tst_QString::remove_string()