qmlformat: Preserve variable declaration scope type

If the user used for(let x;...) we need to preserve the let and must not
change it to var.

Fixes: QTBUG-105361
Change-Id: I49fc3797505b569cc9b8a9138dd57ec7e70d3eb9
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
(cherry picked from commit 84dd339e2eb3385eb143f9d5ab282a135635052d)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

4 files changed, 38 insertions, 8 deletions

diff --git a/src/qmldom/qqmldomreformatter.cpp b/src/qmldom/qqmldomreformatter.cpp
index 4408d3e3a4..bb76f8f772 100644
--- a/src/qmldom/qqmldomreformatter.cpp
+++ b/src/qmldom/qqmldomreformatter.cpp
@@ -552,16 +552,27 @@ protected:
         return false;
     }
 
+
+    void outputScope(VariableScope scope) {
+        switch (scope) {
+        case VariableScope::Const:
+            out("const ");
+            break;
+        case VariableScope::Let:
+            out("let ");
+            break;
+        case VariableScope::Var:
+            out("var ");
+            break;
+        default:
+            break;
+        }
+    }
+
     bool visit(PatternElement *ast) override
     {
         if (ast->isForDeclaration) {
-            if (ast->scope == VariableScope::Var) {
-                out("var ");
-            } else if (ast->scope == VariableScope::Let) {
-                out("let ");
-            } else if (ast->scope == VariableScope::Const) {
-                out("const ");
-            }
+            outputScope(ast->scope);
         }
         accept(ast->bindingTarget);
         switch (ast->type) {
@@ -647,7 +658,7 @@ protected:
         if (ast->initialiser) {
             accept(ast->initialiser);
         } else if (ast->declarations) {
-            out("var ");
+            outputScope(ast->declarations->declaration->scope);
             accept(ast->declarations);
         }
         out("; "); // ast->firstSemicolonToken
diff --git a/tests/auto/qml/qmlformat/data/forWithLet.formatted.qml b/tests/auto/qml/qmlformat/data/forWithLet.formatted.qml
new file mode 100644
index 0000000000..5fecc1d180
--- /dev/null
+++ b/tests/auto/qml/qmlformat/data/forWithLet.formatted.qml
@@ -0,0 +1,8 @@
+import QtQml
+
+QtObject {
+    function foo() {
+        for (let i = 0; i < 5; ++i)
+            console.log(i);
+    }
+}
diff --git a/tests/auto/qml/qmlformat/data/forWithLet.qml b/tests/auto/qml/qmlformat/data/forWithLet.qml
new file mode 100644
index 0000000000..afed76ebce
--- /dev/null
+++ b/tests/auto/qml/qmlformat/data/forWithLet.qml
@@ -0,0 +1,8 @@
+import QtQml
+
+QtObject {
+function foo() {
+for (let i = 0; i < 5; ++i)
+console.log(i);
+}
+}
diff --git a/tests/auto/qml/qmlformat/tst_qmlformat.cpp b/tests/auto/qml/qmlformat/tst_qmlformat.cpp
index 458a36fc54..9d7beb23a7 100644
--- a/tests/auto/qml/qmlformat/tst_qmlformat.cpp
+++ b/tests/auto/qml/qmlformat/tst_qmlformat.cpp
@@ -273,6 +273,9 @@ void TestQmlformat::testFormat_data()
     QTest::newRow("settings") << "settings/Example1.qml"
                               << "settings/Example1.formatted_mac_cr.qml" << QStringList {}
                               << RunOption::OrigToCopy;
+    QTest::newRow("forWithLet")
+            << "forWithLet.qml"
+            << "forWithLet.formatted.qml" << QStringList {} << RunOption::OnCopy;
 }
 
 void TestQmlformat::testFormat()