fix: Do not allow TypeCastExpressions w/o parens inside of SequenceEx…

…pressions
babel · Oct 31, 2018 · e6a6ed3 · e6a6ed3
1 parent 0d9e77f
commit e6a6ed3
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Showing 3 changed files with 25 additions and 1 deletion.
diff --git a/packages/babel-parser/src/plugins/flow.js b/packages/babel-parser/src/plugins/flow.js
@@ -2494,9 +2494,24 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     parseParenAndDistinguishExpression(canBeArrow: boolean): N.Expression {
-      return super.parseParenAndDistinguishExpression(
+      const list = super.parseParenAndDistinguishExpression(
         canBeArrow && this.state.noArrowAt.indexOf(this.state.start) === -1,
       );
+
+      // Ensure that TypeCastExpressions without parens are not allowed inside SequenceExpressions
+      // e.g. (A, B: T)
+      if (list.type === "SequenceExpression") {
+        const firstTypeCast = list.expressions.find(
+          ({ type, extra }) =>
+            type === "TypeCastExpression" &&
+            (!extra || extra.parenthesized !== true),
+        );
+        if (firstTypeCast) {
+          this.unexpected(firstTypeCast.typeAnnotation.start);
+        }
+      }
+
+      return list;
     }
 
     parseSubscripts(

diff --git a/packages/babel-parser/test/fixtures/flow/typecasts/fail-without-parens/input.js b/packages/babel-parser/test/fixtures/flow/typecasts/fail-without-parens/input.js
@@ -0,0 +1 @@
+(A, B: T)
diff --git a/packages/babel-parser/test/fixtures/flow/typecasts/fail-without-parens/options.json b/packages/babel-parser/test/fixtures/flow/typecasts/fail-without-parens/options.json
@@ -0,0 +1,8 @@
+{
+  "sourceType": "module",
+  "plugins": [
+    "jsx",
+    "flow"
+  ],
+  "throws": "Unexpected token (1:5)"
+}