Fix bug when using Array.from with non-array iterable (#1577)

Perryvw · web-flow · commit a07fed5825bc · 2024-09-21T17:44:21.000+02:00
diff --git a/src/lualib/ArrayFrom.ts b/src/lualib/ArrayFrom.ts
@@ -28,8 +28,9 @@ export function __TS__ArrayFrom(
             result.push(v);
         }
     } else {
-        for (const [i, v] of arrayLikeIterator(arrayLike)) {
-            result.push(mapFn.call(thisArg, v, i - 1));
+        let i = 0;
+        for (const [, v] of arrayLikeIterator(arrayLike)) {
+            result.push(mapFn.call(thisArg, v, i++));
         }
     }
     return result;
diff --git a/test/unit/builtins/array.spec.ts b/test/unit/builtins/array.spec.ts
@@ -753,6 +753,14 @@ test.each([
     util.testExpression`Array.from(${valueString})`.expectToMatchJsResult();
 });
 
+// https://github.com/TypeScriptToLua/TypeScriptToLua/issues/1576
+test("array.from with non-array iterable (#1576)", () => {
+    util.testFunction`
+        const map = new Map().set(1, 2);
+        return Array.from(map, ([v,k]) => ({k,v}));
+    `.expectToMatchJsResult();
+});
+
 // Array.of
 test.each(["1, 2, 3", "", "...[1, 2, 3], 4, 5, 6"])("Array.of(%p)", valueString => {
     util.testExpression`Array.of(${valueString})`.expectToMatchJsResult();

Original file line number	Diff line number	Diff line change
`@@ -28,8 +28,9 @@ export function __TS__ArrayFrom(`
`28`	`28`	`result.push(v);`
`29`	`29`	`}`
`30`	`30`	`} else {`
`31`		`- for (const [i, v] of arrayLikeIterator(arrayLike)) {`
`32`		`- result.push(mapFn.call(thisArg, v, i - 1));`
	`31`	`+ let i = 0;`
	`32`	`+ for (const [, v] of arrayLikeIterator(arrayLike)) {`
	`33`	`+ result.push(mapFn.call(thisArg, v, i++));`
`33`	`34`	`}`
`34`	`35`	`}`
`35`	`36`	`return result;`