qmljs: correctly reformat js spread operator (...)

Fixes: QTCREATORBUG-23402
Change-Id: I6b4bd0846dac67116711b7ed046bd52d137b7674
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/libs/qmljs/qmljsreformatter.cpp

@@ -989,6 +989,21 @@ protected:
                 out("const ");
             }
         }
+        switch (ast->type) {
+        case PatternElement::Literal:
+        case PatternElement::Method:
+        case PatternElement::Binding:
+            break;
+        case PatternElement::Getter:
+            out("get ");
+            break;
+        case PatternElement::Setter:
+            out("set ");
+            break;
+        case PatternElement::SpreadElement:
+            out("...");
+            break;
+        }
         out(ast->identifierToken);
         if (ast->initializer) {
             if (ast->isVariableDeclaration())
@@ -1312,6 +1327,8 @@ protected:
     bool visit(ArgumentList *ast) override
     {
         for (ArgumentList *it = ast; it; it = it->next) {
+            if (it->isSpreadElement)
+                out("...");
             accept(it->expression);
             if (it->next) {
                 out(", ", it->commaToken);

tests/auto/qml/reformatter/jssyntax.js

@@ -12,6 +12,17 @@ function foo(a, b) {
 
 var foo = function (a, b) {}
 
+function spread() {
+    iterableObj = [1, 2]
+    obj = {
+        "a": 42
+    }
+    foo(...iterableObj)
+    let arr = [...iterableObj, '4', 'five', 6]
+    foo(-1, ...args, 2, ...[3])
+    console.log(Math.max(...[1, 2, 3, 4]))
+}
+
 const func1 = x => x * 2
 const func2 = x => {
     return x * 7