Handle exprAllowed before ObjectLike is parsed (#12267)

* fix: disallow expression after `}` is consumed in parseObjectLike

* refactor: avoid accessing this.prodParam in context update

packages/babel-parser/src/parser/expression.js

@@ -241,15 +241,15 @@ export default class ExpressionParser extends LValParser {
     const startLoc = this.state.startLoc;
     if (this.isContextual("yield")) {
       if (this.prodParam.hasYield) {
+        // If we have [Yield] production, `yield` will start a YieldExpression thus
+        // regex is allowed following. Otherwise `yield` is an identifier and regex
+        // is disallowed in tt.name.updateContext
+        this.state.exprAllowed = true;
         let left = this.parseYield();
         if (afterLeftParse) {
           left = afterLeftParse.call(this, left, startPos, startLoc);
         }
         return left;
-      } else {
-        // The tokenizer will assume an expression is allowed after
-        // `yield`, but this isn't that kind of yield
-        this.state.exprAllowed = false;
       }
     }
 
@@ -1603,14 +1603,13 @@ export default class ExpressionParser extends LValParser {
     node.properties = [];
     this.next();
 
-    while (!this.eat(close)) {
+    while (!this.match(close)) {
       if (first) {
         first = false;
       } else {
         this.expect(tt.comma);
         if (this.match(close)) {
           this.addExtra(node, "trailingComma", this.state.lastTokStart);
-          this.next();
           break;
         }
       }
@@ -1637,6 +1636,13 @@ export default class ExpressionParser extends LValParser {
       node.properties.push(prop);
     }
 
+    // The tokenizer uses `braceIsBlock` to detect whether `{` starts a block statement.
+    // If `{` is a block statement, `exprAllowed` will be `true`.
+    // However the tokenizer can not handle edge cases like `0 ? a : { a : 1 } / 2`, here
+    // we update `exprAllowed` when an object-like is parsed.
+    this.state.exprAllowed = false;
+    this.next();
+
     this.state.inFSharpPipelineDirectBody = oldInFSharpPipelineDirectBody;
     let type = "ObjectExpression";
     if (isPattern) {

packages/babel-parser/src/tokenizer/context.js

@@ -40,6 +40,14 @@ export const types: {
 };
 
 // Token-specific context update code
+// Note that we should avoid accessing `this.prodParam` in context update,
+// because it is executed immediately when last token is consumed, which may be
+// before `this.prodParam` is updated. e.g.
+// ```
+// function *g() { () => yield / 2 }
+// ```
+// When `=>` is eaten, the context update of `yield` is executed, however,
+// `this.prodParam` still has `[Yield]` production because it is not yet updated
 
 tt.parenR.updateContext = tt.braceR.updateContext = function () {
   if (this.state.context.length === 1) {
@@ -59,11 +67,10 @@ tt.name.updateContext = function (prevType) {
   let allowed = false;
   if (prevType !== tt.dot) {
     if (
-      (this.state.value === "of" &&
+      this.state.value === "of" &&
       !this.state.exprAllowed &&
       prevType !== tt._function &&
-        prevType !== tt._class) ||
+      prevType !== tt._class
-      (this.state.value === "yield" && this.prodParam.hasYield)
     ) {
       allowed = true;
     }

packages/babel-parser/test/fixtures/core/categorized/labeled-block-statement-regex/input.js

@@ -0,0 +1 @@
+a : { b : 1 }/2/;

packages/babel-parser/test/fixtures/core/categorized/labeled-block-statement-regex/output.json

@@ -0,0 +1,64 @@
+{
+  "type": "File",
+  "start":0,"end":17,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":17}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":17,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":17}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "LabeledStatement",
+        "start":0,"end":13,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":13}},
+        "body": {
+          "type": "BlockStatement",
+          "start":4,"end":13,"loc":{"start":{"line":1,"column":4},"end":{"line":1,"column":13}},
+          "body": [
+            {
+              "type": "LabeledStatement",
+              "start":6,"end":11,"loc":{"start":{"line":1,"column":6},"end":{"line":1,"column":11}},
+              "body": {
+                "type": "ExpressionStatement",
+                "start":10,"end":11,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":11}},
+                "expression": {
+                  "type": "NumericLiteral",
+                  "start":10,"end":11,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":11}},
+                  "extra": {
+                    "rawValue": 1,
+                    "raw": "1"
+                  },
+                  "value": 1
+                }
+              },
+              "label": {
+                "type": "Identifier",
+                "start":6,"end":7,"loc":{"start":{"line":1,"column":6},"end":{"line":1,"column":7},"identifierName":"b"},
+                "name": "b"
+              }
+            }
+          ],
+          "directives": []
+        },
+        "label": {
+          "type": "Identifier",
+          "start":0,"end":1,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":1},"identifierName":"a"},
+          "name": "a"
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":13,"end":17,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":17}},
+        "expression": {
+          "type": "RegExpLiteral",
+          "start":13,"end":16,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":16}},
+          "extra": {
+            "raw": "/2/"
+          },
+          "pattern": "2",
+          "flags": ""
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/core/categorized/ternary-object-literal-divide/input.js

@@ -0,0 +1 @@
+0 ? a : { b : 1 }/2;

packages/babel-parser/test/fixtures/core/categorized/ternary-object-literal-divide/output.json

@@ -0,0 +1,76 @@
+{
+  "type": "File",
+  "start":0,"end":20,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":20}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":20,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":20}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":20,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":20}},
+        "expression": {
+          "type": "ConditionalExpression",
+          "start":0,"end":19,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":19}},
+          "test": {
+            "type": "NumericLiteral",
+            "start":0,"end":1,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":1}},
+            "extra": {
+              "rawValue": 0,
+              "raw": "0"
+            },
+            "value": 0
+          },
+          "consequent": {
+            "type": "Identifier",
+            "start":4,"end":5,"loc":{"start":{"line":1,"column":4},"end":{"line":1,"column":5},"identifierName":"a"},
+            "name": "a"
+          },
+          "alternate": {
+            "type": "BinaryExpression",
+            "start":8,"end":19,"loc":{"start":{"line":1,"column":8},"end":{"line":1,"column":19}},
+            "left": {
+              "type": "ObjectExpression",
+              "start":8,"end":17,"loc":{"start":{"line":1,"column":8},"end":{"line":1,"column":17}},
+              "properties": [
+                {
+                  "type": "ObjectProperty",
+                  "start":10,"end":15,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":15}},
+                  "method": false,
+                  "key": {
+                    "type": "Identifier",
+                    "start":10,"end":11,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":11},"identifierName":"b"},
+                    "name": "b"
+                  },
+                  "computed": false,
+                  "shorthand": false,
+                  "value": {
+                    "type": "NumericLiteral",
+                    "start":14,"end":15,"loc":{"start":{"line":1,"column":14},"end":{"line":1,"column":15}},
+                    "extra": {
+                      "rawValue": 1,
+                      "raw": "1"
+                    },
+                    "value": 1
+                  }
+                }
+              ]
+            },
+            "operator": "/",
+            "right": {
+              "type": "NumericLiteral",
+              "start":18,"end":19,"loc":{"start":{"line":1,"column":18},"end":{"line":1,"column":19}},
+              "extra": {
+                "rawValue": 2,
+                "raw": "2"
+              },
+              "value": 2
+            }
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}