QChar: make construction from integral explicit

QChar should not be convertible from any integral type except from
char16_t, short and possibly char (since it's a direct superset).

David provided the perfect example:

  if (str == 123) { ~~~ }

compiles, with 123 implicitly converted to QChar (str == "123"
was meant instead). But similarly one can construct other
scenarios where QString(123) gets accidentally used (instead of
QString::number(123)), like QString s; s += 123;.

Add a macro to revert to the implicit constructors, for backwards
compatibility.

The breaks are mostly in tests that "abuse" of integers (arithmetic,
etc.). Maybe it's time for user-defined literals for QChar/QString,
but that is left for another commit.

[ChangeLog][Potentially Source-Incompatible Changes][QChar] QChar
constructors from integral types are now by default explicit.
It is recommended to use explicit conversions, QLatin1Char,
QChar::fromUcs4 instead of implicit conversions. The old behavior
can be restored by defining the QT_IMPLICIT_QCHAR_CONSTRUCTION
macro.

Change-Id: I6175f6ab9bcf1956f6f97ab0c9d9d5aaf777296d
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

1 files changed, 8 insertions, 8 deletions

diff --git a/tests/benchmarks/gui/image/qpixmapcache/tst_qpixmapcache.cpp b/tests/benchmarks/gui/image/qpixmapcache/tst_qpixmapcache.cpp
index 2ded426cdd..b1f1a4c083 100644
--- a/tests/benchmarks/gui/image/qpixmapcache/tst_qpixmapcache.cpp
+++ b/tests/benchmarks/gui/image/qpixmapcache/tst_qpixmapcache.cpp
@@ -164,12 +164,12 @@ void tst_QPixmapCache::styleUseCaseComplexKey()
             {
                 styleStruct myStruct;
                 myStruct.key = QString("my-progressbar-%1").arg(i);
-                myStruct.key = 5;
-                myStruct.key = 4;
-                myStruct.key = 3;
+                myStruct.key = QChar(5);
+                myStruct.key = QChar(4);
+                myStruct.key = QChar(3);
                 myStruct.palette = 358;
                 myStruct.width = 100;
-                myStruct.key = 200;
+                myStruct.key = QChar(200);
                 QPixmapCache::Key key = QPixmapCache::insert(p);
                 hash.insert(myStruct, key);
             }
@@ -177,12 +177,12 @@ void tst_QPixmapCache::styleUseCaseComplexKey()
             {
                 styleStruct myStruct;
                 myStruct.key = QString("my-progressbar-%1").arg(i);
-                myStruct.key = 5;
-                myStruct.key = 4;
-                myStruct.key = 3;
+                myStruct.key = QChar(5);
+                myStruct.key = QChar(4);
+                myStruct.key = QChar(3);
                 myStruct.palette = 358;
                 myStruct.width = 100;
-                myStruct.key = 200;
+                myStruct.key = QChar(200);
                 QPixmapCache::Key key = hash.value(myStruct);
                 QPixmapCache::find(key, &p);
             }