fix: Capture let when the for body is not a block (#16368)

packages/babel-plugin-transform-block-scoping/src/index.ts

@@ -57,12 +57,11 @@ export default declare((api, opts: Options) => {
           let bodyScope: Scope | null;
           if (body.isBlockStatement()) {
             bodyScope = body.scope;
-
-            const bindings = getLoopBodyBindings(path);
-            for (const binding of bindings) {
-              const { capturedInClosure } = getUsageInBody(binding, path);
-              if (capturedInClosure) markNeedsBodyWrap();
-            }
+          }
+          const bindings = getLoopBodyBindings(path);
+          for (const binding of bindings) {
+            const { capturedInClosure } = getUsageInBody(binding, path);
+            if (capturedInClosure) markNeedsBodyWrap();
           }
 
           const captured: string[] = [];

packages/babel-plugin-transform-block-scoping/test/fixtures/general/for-without-block/exec.js

@@ -0,0 +1,18 @@
+function proxyObserver(properties) {
+  for (let key in properties)
+    if (properties[key].observer) {
+      let base = properties[key].observer;
+      properties[key].observer = () => {
+        return base.apply(this);
+      };
+    }
+
+  return properties;
+}
+
+const results = proxyObserver([
+  { observer: () => 1 },
+  { observer: () => 2 },
+])
+expect(results[0].observer()).toBe(1)
+expect(results[1].observer()).toBe(2)

packages/babel-plugin-transform-block-scoping/test/fixtures/general/for-without-block/input.js

@@ -0,0 +1,23 @@
+function proxyObserver(component) {
+  for (let key in component.properties)
+    if (component.properties[key].observer) {
+      let base = component.properties[key].observer;
+      component.properties[key].observer = () => {
+        base.apply(this);
+      };
+    }
+
+  return component;
+}
+
+function proxyObserver2(component) {
+  for (let key of component.properties)
+    while (1) {
+      let base = component.properties[key].observer;
+      component.properties[key].observer = () => {
+        base.apply(this);
+      };
+    }
+
+  return component;
+}

packages/babel-plugin-transform-block-scoping/test/fixtures/general/for-without-block/output.js

@@ -0,0 +1,30 @@
+function proxyObserver(component) {
+  var _this = this;
+  var _loop = function () {
+    if (component.properties[key].observer) {
+      var base = component.properties[key].observer;
+      component.properties[key].observer = function () {
+        base.apply(_this);
+      };
+    }
+  };
+  for (var key in component.properties) {
+    _loop();
+  }
+  return component;
+}
+function proxyObserver2(component) {
+  var _this2 = this;
+  for (var key of component.properties) {
+    var _loop2 = function () {
+      var base = component.properties[key].observer;
+      component.properties[key].observer = function () {
+        base.apply(_this2);
+      };
+    };
+    while (1) {
+      _loop2();
+    }
+  }
+  return component;
+}