Add explicit exception for 'async of' not starting arrow in for init …

…context FIX: Fix issue where the library couldn't parse 'for (async of ...)'. Closes #1031
acornjs · May 4, 2021 · 7cbe0f9 · 7cbe0f9
1 parent 556a7ab
commit 7cbe0f9
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Showing 3 changed files with 8 additions and 2 deletions.
diff --git a/acorn/src/expression.js b/acorn/src/expression.js
@@ -124,8 +124,10 @@ pp.parseMaybeAssign = function(noIn, refDestructuringErrors, afterLeftParse) {
   }
 
   let startPos = this.start, startLoc = this.startLoc
-  if (this.type === tt.parenL || this.type === tt.name)
+  if (this.type === tt.parenL || this.type === tt.name) {
     this.potentialArrowAt = this.start
+    this.forbidAsyncOfArrow = !!noIn
+  }
   let left = this.parseMaybeConditional(noIn, refDestructuringErrors)
   if (afterLeftParse) left = afterLeftParse.call(this, left, startPos, startLoc)
   if (this.type.isAssign) {
@@ -414,7 +416,8 @@ pp.parseExprAtom = function(refDestructuringErrors) {
     if (canBeArrow && !this.canInsertSemicolon()) {
       if (this.eat(tt.arrow))
         return this.parseArrowExpression(this.startNodeAt(startPos, startLoc), [id], false)
-      if (this.options.ecmaVersion >= 8 && id.name === "async" && this.type === tt.name && !containsEsc) {
+      if (this.options.ecmaVersion >= 8 && id.name === "async" && this.type === tt.name && !containsEsc &&
+          (!this.forbidAsyncOfArrow || this.value !== "of" || this.containsEsc)) {
         id = this.parseIdent(false)
         if (this.canInsertSemicolon() || !this.eat(tt.arrow))
           this.unexpected()

diff --git a/acorn/src/state.js b/acorn/src/state.js
@@ -65,6 +65,7 @@ export class Parser {
 
     // Used to signify the start of a potential arrow function
     this.potentialArrowAt = -1
+    this.forbidAsyncOfArrow = false
 
     // Positions to delayed-check that yield/await does not exist in default parameters.
     this.yieldPos = this.awaitPos = this.awaitIdentPos = 0

diff --git a/test/tests-asyncawait.js b/test/tests-asyncawait.js
@@ -3522,6 +3522,8 @@ test(
 
 test("({ async delete() {} })", {}, {ecmaVersion: 8})
 
+test("for (async of []) {}", {}, {ecmaVersion: 8})
+
 testFail("abc: async function a() {}", "Unexpected token (1:5)", {ecmaVersion: 8})
 
 testFail("(async() => { await 4 ** 2 })()", "Unexpected token (1:22)", {ecmaVersion: 8})