Revert "Revert "Merge remote-tracking branch 'origin/4.15'""

This reverts commit f0a86d4510.

Reverting a merge doesn't "undo" it - the changes would be lost
forever even with subsequent merges.
So we need to revert the revert to get the changes.

Change-Id: I65928f876f4dc886561bed17c4b2aa42b388c1e3
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/libs/qmljs/qmljscheck.cpp

@@ -1366,7 +1366,9 @@ bool Check::visit(Block *ast)
                 && !cast<WhileStatement *>(p)
                 && !cast<IfStatement *>(p)
                 && !cast<SwitchStatement *>(p)
-                && !cast<WithStatement *>(p)) {
+                && !isCaseOrDefault(p)
+                && !cast<WithStatement *>(p)
+                && hasVarStatement(ast)) {
             addMessage(WarnBlock, ast->lbraceToken);
         }
         if (!ast->statements
@@ -1656,6 +1658,33 @@ bool Check::isQtQuick2Ui() const
     return _doc->language() == Dialect::QmlQtQuick2Ui;
 }
 
+bool Check::isCaseOrDefault(Node *n)
+{
+    if (!cast<StatementList *>(n))
+        return false;
+    if (Node *p = parent(1))
+        return p->kind == Node::Kind_CaseClause || p->kind == Node::Kind_DefaultClause;
+    return false;
+}
+
+bool Check::hasVarStatement(AST::Block *b) const
+{
+    QTC_ASSERT(b, return false);
+    StatementList *s = b->statements;
+    while (s) {
+        if (auto var = cast<VariableStatement *>(s->statement)) {
+            VariableDeclarationList *declList = var->declarations;
+            while (declList) {
+                if (declList->declaration && declList->declaration->scope == VariableScope::Var)
+                    return true;
+                declList = declList->next;
+            }
+        }
+        s = s->next;
+    }
+    return false;
+}
+
 bool Check::visit(NewExpression *ast)
 {
     checkNewExpression(ast->expression);