From fcbf446616cf0b3e4b9ad5a37ca7368e9f84fde7 Mon Sep 17 00:00:00 2001
From: Perryvw <perry.wesel@gmail.com>
Date: Mon, 21 Dec 2020 14:46:31 +0100
Subject: [PATCH] Fixed incorrect variable declarations in some cases when
 there is no initializer

---
 src/transformation/utils/lua-ast.ts |  4 +++-
 test/unit/hoisting.spec.ts          | 11 +++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/transformation/utils/lua-ast.ts b/src/transformation/utils/lua-ast.ts
index b9b600c90..91e81bc9a 100644
--- a/src/transformation/utils/lua-ast.ts
+++ b/src/transformation/utils/lua-ast.ts
@@ -176,7 +176,9 @@ export function createLocalOrExportedOrGlobalDeclaration(
             if (scope.type === ScopeType.Switch || (!isFunctionDeclaration && hasMultipleReferences(scope, lhs))) {
                 // Split declaration and assignment of identifiers that reference themselves in their declaration
                 declaration = lua.createVariableDeclarationStatement(lhs, undefined, tsOriginal);
-                assignment = lua.createAssignmentStatement(lhs, rhs, tsOriginal);
+                if (rhs) {
+                    assignment = lua.createAssignmentStatement(lhs, rhs, tsOriginal);
+                }
             } else {
                 declaration = lua.createVariableDeclarationStatement(lhs, rhs, tsOriginal);
             }
diff --git a/test/unit/hoisting.spec.ts b/test/unit/hoisting.spec.ts
index 997c53f73..16172b410 100644
--- a/test/unit/hoisting.spec.ts
+++ b/test/unit/hoisting.spec.ts
@@ -254,3 +254,14 @@ test("Hoisting Shorthand Property", () => {
         return foo();`;
     expect(util.transpileAndExecute(code)).toBe("foobar");
 });
+
+// https://github.com/TypeScriptToLua/TypeScriptToLua/issues/944
+test("Hoisting variable without initializer", () => {
+    util.testFunction`
+        function foo() {
+            return x;
+        }
+        let x: number;
+        return foo();
+    `.expectToMatchJsResult();
+});