Fix parenthesis for nullish coalescing (#10269)

* ♻️ added condition to check for left and right of nullish coalescing operator and if any is a logical expression without a paren then throw an error

* 🐛 bugs fixed and test cases updated for babel parser

* ♻️ code comments added

* 🐛 spell error rectified

* ♻️ failing test updated

* 🐛 push tests after make build

* Skip nullish-coalescing flow precedence tests

They're now incorrect

* ♻️ error message updated, binop priority of other logical operators +1 from ?? and

* ♻️ increaed the binOp for in and instanceOf, added logic to print the brackets in an ?? && || expression, test cases added

* 🐛 failing test fixed and comments updated

* ♻️ new lines added between tests

* ♻️ basic tests for checking the binOp of instanceOf, in and relational operators to be equal added

* ♻️ new lines added in between tests

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

@@ -380,6 +380,39 @@ export default class ExpressionParser extends LValParser {
 
         node.right = this.parseExprOpRightExpr(op, prec, noIn);
 
+        /* this check is for all ?? operators
+         * a ?? b && c for this example
+         * b && c => This is considered as a logical expression in the ast tree
+         * a => Identifier
+         * so for ?? operator we need to check in this case the right expression to have parenthesis
+         * second case a && b ?? c
+         * here a && b => This is considered as a logical expression in the ast tree
+         * c => identifer
+         * so now here for ?? operator we need to check the left expression to have parenthesis
+         * if the parenthesis is missing we raise an error and throw it
+         */
+        if (op === tt.nullishCoalescing) {
+          if (
+            left.type === "LogicalExpression" &&
+            left.operator !== "??" &&
+            !(left.extra && left.extra.parenthesized)
+          ) {
+            throw this.raise(
+              left.start,
+              `Nullish coalescing operator(??) requires parens when mixing with logical operators`,
+            );
+          } else if (
+            node.right.type === "LogicalExpression" &&
+            node.right.operator !== "??" &&
+            !(node.right.extra && node.right.extra.parenthesized)
+          ) {
+            throw this.raise(
+              node.right.start,
+              `Nullish coalescing operator(??) requires parens when mixing with logical operators`,
+            );
+          }
+        }
+
         this.finishNode(
           node,
           op === tt.logicalOR ||

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

@@ -139,21 +139,21 @@ export const types: { [name: string]: TokenType } = {
   tilde: new TokenType("~", { beforeExpr, prefix, startsExpr }),
   pipeline: createBinop("|>", 0),
   nullishCoalescing: createBinop("??", 1),
-  logicalOR: createBinop("||", 1),
-  logicalAND: createBinop("&&", 2),
-  bitwiseOR: createBinop("|", 3),
-  bitwiseXOR: createBinop("^", 4),
-  bitwiseAND: createBinop("&", 5),
-  equality: createBinop("==/!=/===/!==", 6),
-  relational: createBinop("</>/<=/>=", 7),
-  bitShift: createBinop("<</>>/>>>", 8),
-  plusMin: new TokenType("+/-", { beforeExpr, binop: 9, prefix, startsExpr }),
-  modulo: createBinop("%", 10),
-  star: createBinop("*", 10),
-  slash: createBinop("/", 10),
+  logicalOR: createBinop("||", 2),
+  logicalAND: createBinop("&&", 3),
+  bitwiseOR: createBinop("|", 4),
+  bitwiseXOR: createBinop("^", 5),
+  bitwiseAND: createBinop("&", 6),
+  equality: createBinop("==/!=/===/!==", 7),
+  relational: createBinop("</>/<=/>=", 8),
+  bitShift: createBinop("<</>>/>>>", 9),
+  plusMin: new TokenType("+/-", { beforeExpr, binop: 10, prefix, startsExpr }),
+  modulo: createBinop("%", 11),
+  star: createBinop("*", 11),
+  slash: createBinop("/", 11),
   exponent: new TokenType("**", {
     beforeExpr,
-    binop: 11,
+    binop: 12,
     rightAssociative: true,
   }),
 
@@ -188,8 +188,8 @@ export const types: { [name: string]: TokenType } = {
   _null: createKeyword("null", { startsExpr }),
   _true: createKeyword("true", { startsExpr }),
   _false: createKeyword("false", { startsExpr }),
-  _in: createKeyword("in", { beforeExpr, binop: 7 }),
-  _instanceof: createKeyword("instanceof", { beforeExpr, binop: 7 }),
+  _in: createKeyword("in", { beforeExpr, binop: 8 }),
+  _instanceof: createKeyword("instanceof", { beforeExpr, binop: 8 }),
   _typeof: createKeyword("typeof", { beforeExpr, prefix, startsExpr }),
   _void: createKeyword("void", { beforeExpr, prefix, startsExpr }),
   _delete: createKeyword("delete", { beforeExpr, prefix, startsExpr }),