QmlCompiler: Consider lengths to be qsizetype

This is what we get as "source material" from all the containers. In
JavaScript, arrays sizes are up to 32bit unsigned, but we need to
represent -1 in a few places. Therefore, we cannot clamp the result to
32bit signed if the underlying container supports 64bit indices.

We can change qjslist.h here because this header is only supposed to be
used from generated code. Therefore, if you rebuild any users of this
code, you will also re-generate them, adapting to the new API.

Since we check for QJSNumberCoercion::isArrayIndex() before we use any
number as an array index when generating code, this is actually safe. We
just need to adapt isArrayIndex() to consider numbers greater than
INT_MAX as possible values.

Fixes: QTBUG-122582
Change-Id: I1147978a05bfedb63037c7f4437921f85a6aabb1
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

2 files changed, 30 insertions, 5 deletions

diff --git a/src/qml/common/qjsnumbercoercion.cpp b/src/qml/common/qjsnumbercoercion.cpp
index ba76c12bb0..8cd96a4e25 100644
--- a/src/qml/common/qjsnumbercoercion.cpp
+++ b/src/qml/common/qjsnumbercoercion.cpp
@@ -24,10 +24,26 @@ QT_BEGIN_NAMESPACE
   \internal
 
   Checks whether \a d contains a value that can serve as an index into an array.
-  For that, \a d must be a non-negative value representable as an int.
+  For that, \a d must be a non-negative value representable as an unsigned 32bit int.
  */
 
 /*!
+  \fn bool QJSNumberCoercion::isArrayIndex(qint64 i)
+  \internal
+
+  Checks whether \a i contains a value that can serve as an index into an array.
+  For that, \a d must be a non-negative value representable as an unsigned 32bit int.
+*/
+
+/*!
+  \fn bool QJSNumberCoercion::isArrayIndex(quint64 i)
+  \internal
+
+  Checks whether \a i contains a value that can serve as an index into an array.
+  For that, \a d must be a value representable as an unsigned 32bit int.
+*/
+
+/*!
   \fn int QJSNumberCoercion::toInteger(double d)
   \internal
 
diff --git a/src/qml/common/qjsnumbercoercion.h b/src/qml/common/qjsnumbercoercion.h
index 569976454f..0023bff6e8 100644
--- a/src/qml/common/qjsnumbercoercion.h
+++ b/src/qml/common/qjsnumbercoercion.h
@@ -27,11 +27,20 @@ public:
 
     static constexpr bool isArrayIndex(double d)
     {
-        if (d < 0 || !equals(d, d) || d > (std::numeric_limits<int>::max)()) {
-            return false;
-        }
+        return d >= 0
+                && equals(d, d)
+                && d <= (std::numeric_limits<uint>::max)()
+                && equals(static_cast<uint>(d), d);
+    }
 
-        return equals(static_cast<int>(d), d);
+    static constexpr bool isArrayIndex(qint64 i)
+    {
+        return i >= 0 && i <= (std::numeric_limits<uint>::max)();
+    }
+
+    static constexpr bool isArrayIndex(quint64 i)
+    {
+        return i <= (std::numeric_limits<uint>::max)();
     }
 
     static constexpr int toInteger(double d) {