fix: Destructuring empty in nested for expressions (#14841)

liuxingbaoyu · JLHwung · web-flow · commit 614d98b71679 · 2022-08-10T11:19:38.000-04:00
* fix

* Update packages/babel-plugin-transform-destructuring/src/util.ts

Co-authored-by: Huáng Jùnliàng &lt;jlhwung@gmail.com&gt;

* review

* review

Co-authored-by: Huáng Jùnliàng &lt;jlhwung@gmail.com&gt;
diff --git a/packages/babel-plugin-transform-destructuring/src/util.ts b/packages/babel-plugin-transform-destructuring/src/util.ts
@@ -327,7 +327,6 @@ export class DestructuringTransformer {
         }
       }
     }
-    //
 
     for (let i = 0; i < pattern.properties.length; i++) {
       const prop = pattern.properties[i];
@@ -484,8 +483,6 @@ export class DestructuringTransformer {
       }
     }
 
-    //
-
     this.push(pattern, ref);
 
     return this.nodes;
@@ -620,6 +617,8 @@ export function convertVariableDeclaration(
     }
   }
 
+  const inForInit = t.isForStatement(path.parent, { init: node });
+
   let tail: t.VariableDeclaration | null = null;
   const nodesOut = [];
   for (const node of nodes) {
@@ -640,7 +639,9 @@ export function convertVariableDeclaration(
     if (!node.loc) {
       node.loc = nodeLoc;
     }
-    nodesOut.push(node);
+    nodesOut.push(
+      inForInit && node.type === "ExpressionStatement" ? node.expression : node,
+    );
   }
 
   if (nodesOut.length === 1) {
diff --git a/packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/destructuring-empty-in-for/input.js b/packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/destructuring-empty-in-for/input.js
@@ -0,0 +1,5 @@
+for ( let x in y ) for ( ; ; ) var { } = x ;
+
+for ( let x in y ) for ( var { } = x ; ; ) ;
+
+for ( let x in y ) for ( ; { } = x ; {} = x ) var { } = x ;
diff --git a/packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/destructuring-empty-in-for/output.js b/packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/destructuring-empty-in-for/output.js
@@ -0,0 +1,19 @@
+for (var x in y) {
+  for (;;) {
+    babelHelpers.objectDestructuringEmpty(x);
+  }
+}
+
+for (var _x in y) {
+  for (babelHelpers.objectDestructuringEmpty(_x);;) {
+    ;
+  }
+}
+
+for (var _x2 in y) {
+  for (; _x3 = _x2, babelHelpers.objectDestructuringEmpty(_x3), _x3; _x4 = _x2, babelHelpers.objectDestructuringEmpty(_x4), _x4) {
+    var _x3, _x4;
+
+    babelHelpers.objectDestructuringEmpty(_x2);
+  }
+}

Original file line number	Diff line number	Diff line change
`@@ -327,7 +327,6 @@ export class DestructuringTransformer {`
`327`	`327`	`}`
`328`	`328`	`}`
`329`	`329`	`}`
`330`		`- //`
`331`	`330`
`332`	`331`	`for (let i = 0; i < pattern.properties.length; i++) {`
`333`	`332`	`const prop = pattern.properties[i];`
`@@ -484,8 +483,6 @@ export class DestructuringTransformer {`
`484`	`483`	`}`
`485`	`484`	`}`
`486`	`485`
`487`		`- //`
`488`		`-`
`489`	`486`	`this.push(pattern, ref);`
`490`	`487`
`491`	`488`	`return this.nodes;`
`@@ -620,6 +617,8 @@ export function convertVariableDeclaration(`
`620`	`617`	`}`
`621`	`618`	`}`
`622`	`619`
	`620`	`+ const inForInit = t.isForStatement(path.parent, { init: node });`
	`621`	`+`
`623`	`622`	`let tail: t.VariableDeclaration \| null = null;`
`624`	`623`	`const nodesOut = [];`
`625`	`624`	`for (const node of nodes) {`
`@@ -640,7 +639,9 @@ export function convertVariableDeclaration(`
`640`	`639`	`if (!node.loc) {`
`641`	`640`	`node.loc = nodeLoc;`
`642`	`641`	`}`
`643`		`- nodesOut.push(node);`
	`642`	`+ nodesOut.push(`
	`643`	`+ inForInit && node.type === "ExpressionStatement" ? node.expression : node,`
	`644`	`+ );`
`644`	`645`	`}`
`645`	`646`
`646`	`647`	`if (nodesOut.length === 1) {`