Port "Fixed nullish coalesce operator's precedence" (#1824)

Andarist · web-flow · commit 0fbc06e95f48 · 2025-10-06T19:00:25.000Z
diff --git a/internal/ast/precedence.go b/internal/ast/precedence.go
@@ -43,15 +43,6 @@ const (
 	//     ShortCircuitExpression
 	//     ShortCircuitExpression `?` AssignmentExpression `:` AssignmentExpression
 	OperatorPrecedenceConditional
-	// ShortCircuitExpression:
-	//     LogicalORExpression
-	//     CoalesceExpression
-	// CoalesceExpression:
-	//     CoalesceExpressionHead `??` BitwiseORExpression
-	// CoalesceExpressionHead:
-	//     CoalesceExpression
-	//     BitwiseORExpression
-	OperatorPrecedenceCoalesce
 	// LogicalORExpression:
 	//     LogicalANDExpression
 	//     LogicalORExpression `||` LogicalANDExpression
@@ -181,6 +172,15 @@ const (
 	OperatorPrecedenceLowest        = OperatorPrecedenceComma
 	OperatorPrecedenceHighest       = OperatorPrecedenceParentheses
 	OperatorPrecedenceDisallowComma = OperatorPrecedenceYield
+	// ShortCircuitExpression:
+	//     LogicalORExpression
+	//     CoalesceExpression
+	// CoalesceExpression:
+	//     CoalesceExpressionHead `??` BitwiseORExpression
+	// CoalesceExpressionHead:
+	//     CoalesceExpression
+	//     BitwiseORExpression
+	OperatorPrecedenceCoalesce = OperatorPrecedenceLogicalOR
 	// -1 is lower than all other precedences. Returning it will cause binary expression
 	// parsing to stop.
 	OperatorPrecedenceInvalid OperatorPrecedence = -1
diff --git a/internal/checker/checker.go b/internal/checker/checker.go
@@ -12409,11 +12409,22 @@ func (c *Checker) getSyntacticTruthySemantics(node *ast.Node) PredicateSemantics
 }
 
 func (c *Checker) checkNullishCoalesceOperands(left *ast.Node, right *ast.Node) {
-	if ast.IsBinaryExpression(left) && ast.IsLogicalBinaryOperator(left.AsBinaryExpression().OperatorToken.Kind) {
-		c.grammarErrorOnNode(left, diagnostics.X_0_and_1_operations_cannot_be_mixed_without_parentheses, scanner.TokenToString(left.AsBinaryExpression().OperatorToken.Kind), scanner.TokenToString(ast.KindQuestionQuestionToken))
-	}
-	if ast.IsBinaryExpression(right) && ast.IsLogicalBinaryOperator(right.AsBinaryExpression().OperatorToken.Kind) {
-		c.grammarErrorOnNode(right, diagnostics.X_0_and_1_operations_cannot_be_mixed_without_parentheses, scanner.TokenToString(right.AsBinaryExpression().OperatorToken.Kind), scanner.TokenToString(ast.KindQuestionQuestionToken))
+	if ast.IsBinaryExpression(left.Parent.Parent) {
+		grandparentLeft := left.Parent.Parent.AsBinaryExpression().Left
+		grandparentOperatorToken := left.Parent.Parent.AsBinaryExpression().OperatorToken
+		if ast.IsBinaryExpression(grandparentLeft) && grandparentOperatorToken.Kind == ast.KindBarBarToken {
+			c.grammarErrorOnNode(grandparentLeft, diagnostics.X_0_and_1_operations_cannot_be_mixed_without_parentheses, scanner.TokenToString(ast.KindQuestionQuestionToken), scanner.TokenToString(grandparentOperatorToken.Kind))
+		}
+	} else if ast.IsBinaryExpression(left) {
+		operatorToken := left.AsBinaryExpression().OperatorToken
+		if operatorToken.Kind == ast.KindBarBarToken || operatorToken.Kind == ast.KindAmpersandAmpersandToken {
+			c.grammarErrorOnNode(left, diagnostics.X_0_and_1_operations_cannot_be_mixed_without_parentheses, scanner.TokenToString(operatorToken.Kind), scanner.TokenToString(ast.KindQuestionQuestionToken))
+		}
+	} else if ast.IsBinaryExpression(right) {
+		operatorToken := right.AsBinaryExpression().OperatorToken
+		if operatorToken.Kind == ast.KindAmpersandAmpersandToken {
+			c.grammarErrorOnNode(right, diagnostics.X_0_and_1_operations_cannot_be_mixed_without_parentheses, scanner.TokenToString(ast.KindQuestionQuestionToken), scanner.TokenToString(operatorToken.Kind))
+		}
 	}
 	c.checkNullishCoalesceOperandLeft(left)
 	c.checkNullishCoalesceOperandRight(right)
diff --git a/internal/printer/printer.go b/internal/printer/printer.go
@@ -2716,14 +2716,6 @@ func (p *Printer) getBinaryExpressionPrecedence(node *ast.BinaryExpression) (lef
 	case ast.OperatorPrecedenceAssignment:
 		// assignment is right-associative
 		leftPrec = ast.OperatorPrecedenceLeftHandSide
-	case ast.OperatorPrecedenceCoalesce:
-		// allow coalesce on the left, but short circuit to BitwiseOR
-		if isBinaryOperation(node.Left, ast.KindQuestionQuestionToken) {
-			leftPrec = ast.OperatorPrecedenceCoalesce
-		} else {
-			leftPrec = ast.OperatorPrecedenceBitwiseOR
-		}
-		rightPrec = ast.OperatorPrecedenceBitwiseOR
 	case ast.OperatorPrecedenceLogicalOR:
 		rightPrec = ast.OperatorPrecedenceLogicalAND
 	case ast.OperatorPrecedenceLogicalAND:
diff --git a/testdata/baselines/reference/submodule/conformance/nullishCoalescingOperator5.errors.txt b/testdata/baselines/reference/submodule/conformance/nullishCoalescingOperator5.errors.txt
@@ -1,6 +1,6 @@
-nullishCoalescingOperator5.ts(6,6): error TS5076: '||' and '??' operations cannot be mixed without parentheses.
+nullishCoalescingOperator5.ts(6,1): error TS5076: '??' and '||' operations cannot be mixed without parentheses.
 nullishCoalescingOperator5.ts(9,1): error TS5076: '||' and '??' operations cannot be mixed without parentheses.
-nullishCoalescingOperator5.ts(12,6): error TS5076: '&&' and '??' operations cannot be mixed without parentheses.
+nullishCoalescingOperator5.ts(12,6): error TS5076: '??' and '&&' operations cannot be mixed without parentheses.
 nullishCoalescingOperator5.ts(15,1): error TS5076: '&&' and '??' operations cannot be mixed without parentheses.
 
 
@@ -11,8 +11,8 @@ nullishCoalescingOperator5.ts(15,1): error TS5076: '&&' and '??' operations cann
     
     // should be a syntax error
     a ?? b || c;
-         ~~~~~~
-!!! error TS5076: '||' and '??' operations cannot be mixed without parentheses.
+    ~~~~~~
+!!! error TS5076: '??' and '||' operations cannot be mixed without parentheses.
     
     // should be a syntax error
     a || b ?? c;
@@ -22,7 +22,7 @@ nullishCoalescingOperator5.ts(15,1): error TS5076: '&&' and '??' operations cann
     // should be a syntax error
     a ?? b && c;
          ~~~~~~
-!!! error TS5076: '&&' and '??' operations cannot be mixed without parentheses.
+!!! error TS5076: '??' and '&&' operations cannot be mixed without parentheses.
     
     // should be a syntax error
     a && b ?? c;
diff --git a/testdata/baselines/reference/submodule/conformance/nullishCoalescingOperator5.errors.txt.diff b/testdata/baselines/reference/submodule/conformance/nullishCoalescingOperator5.errors.txt.diff
diff --git a/testdata/baselines/reference/submodule/conformance/nullishCoalescingOperator5.js b/testdata/baselines/reference/submodule/conformance/nullishCoalescingOperator5.js
@@ -45,7 +45,7 @@ a && (b ?? c);
 //// [nullishCoalescingOperator5.js]
 var _a, _b, _c, _d;
 // should be a syntax error
-a !== null && a !== void 0 ? a : b || c;
+(a !== null && a !== void 0 ? a : b) || c;
 // should be a syntax error
 (_a = a || b) !== null && _a !== void 0 ? _a : c;
 // should be a syntax error
diff --git a/testdata/baselines/reference/submodule/conformance/nullishCoalescingOperator5.js.diff b/testdata/baselines/reference/submodule/conformance/nullishCoalescingOperator5.js.diff
@@ -7,8 +7,4 @@
 -"use strict";
  var _a, _b, _c, _d;
  // should be a syntax error
--(a !== null && a !== void 0 ? a : b) || c;
-+a !== null && a !== void 0 ? a : b || c;
- // should be a syntax error
- (_a = a || b) !== null && _a !== void 0 ? _a : c;
- // should be a syntax error
+ (a !== null && a !== void 0 ? a : b) || c;
diff --git a/testdata/baselines/reference/submodule/conformance/nullishCoalescingOperator5.types b/testdata/baselines/reference/submodule/conformance/nullishCoalescingOperator5.types
@@ -13,8 +13,8 @@ declare const c: string | undefined
 // should be a syntax error
 a ?? b || c;
 >a ?? b || c : string | undefined
+>a ?? b : string | undefined
 >a : string | undefined
->b || c : string | undefined
 >b : string | undefined
 >c : string | undefined
 
diff --git a/testdata/baselines/reference/submodule/conformance/nullishCoalescingOperator5.types.diff b/testdata/baselines/reference/submodule/conformance/nullishCoalescingOperator5.types.diff
diff --git a/testdata/baselines/reference/submodule/conformance/plainJSGrammarErrors.errors.txt b/testdata/baselines/reference/submodule/conformance/plainJSGrammarErrors.errors.txt
@@ -58,7 +58,7 @@ plainJSGrammarErrors.js(92,33): error TS2566: A rest element cannot have a prope
 plainJSGrammarErrors.js(93,42): error TS1186: A rest element cannot have an initializer.
 plainJSGrammarErrors.js(96,4): error TS1123: Variable declaration list cannot be empty.
 plainJSGrammarErrors.js(97,9): error TS5076: '||' and '??' operations cannot be mixed without parentheses.
-plainJSGrammarErrors.js(98,14): error TS5076: '||' and '??' operations cannot be mixed without parentheses.
+plainJSGrammarErrors.js(98,9): error TS5076: '??' and '||' operations cannot be mixed without parentheses.
 plainJSGrammarErrors.js(100,3): error TS1200: Line terminator not permitted before arrow.
 plainJSGrammarErrors.js(102,4): error TS1358: Tagged template expressions are not permitted in an optional chain.
 plainJSGrammarErrors.js(104,6): error TS1171: A comma expression is not allowed in a computed property name.
@@ -320,8 +320,8 @@ plainJSGrammarErrors.js(205,36): error TS1325: Argument of dynamic import cannot
             ~~~~~~
 !!! error TS5076: '||' and '??' operations cannot be mixed without parentheses.
     var x = 2 ?? 3 || 4
-                 ~~~~~~
-!!! error TS5076: '||' and '??' operations cannot be mixed without parentheses.
+            ~~~~~~
+!!! error TS5076: '??' and '||' operations cannot be mixed without parentheses.
     const arr = x
       => x + 1
       ~~
diff --git a/testdata/baselines/reference/submodule/conformance/plainJSGrammarErrors.js b/testdata/baselines/reference/submodule/conformance/plainJSGrammarErrors.js
@@ -303,8 +303,8 @@ const { e: eep, m: em, ...rest: noRestAllowed } = doom;
 const { e: erp, m: erm, ...noInitialiser = true } = doom;
 // left-over parsing
 var ;
-var x = (1 || 2) ?? 3;
-var x = 2 ?? (3 || 4);
+var x = 1 || 2 ?? 3;
+var x = 2 ?? 3 || 4;
 const arr = x => x + 1;
 var a = [1, 2];
 a `length`;
diff --git a/testdata/baselines/reference/submodule/conformance/plainJSGrammarErrors.js.diff b/testdata/baselines/reference/submodule/conformance/plainJSGrammarErrors.js.diff
@@ -38,15 +38,7 @@
  export import 'fs';
  export { C };
  function nestedExports() {
-@@= skipped -30, +30 lines =@@
- const { e: erp, m: erm, ...noInitialiser = true } = doom;
- // left-over parsing
- var ;
--var x = 1 || 2 ?? 3;
--var x = 2 ?? 3 || 4;
-+var x = (1 || 2) ?? 3;
-+var x = 2 ?? (3 || 4);
- const arr = x => x + 1;
+@@= skipped -36, +36 lines =@@
  var a = [1, 2];
  a `length`;
  const o = {
diff --git a/testdata/baselines/reference/submodule/conformance/plainJSGrammarErrors.types b/testdata/baselines/reference/submodule/conformance/plainJSGrammarErrors.types
@@ -278,8 +278,8 @@ var x = 1 || 2 ?? 3
 var x = 2 ?? 3 || 4
 >x : number
 >2 ?? 3 || 4 : 2 | 3 | 4
+>2 ?? 3 : 2 | 3
 >2 : 2
->3 || 4 : 3 | 4
 >3 : 3
 >4 : 4
 
diff --git a/testdata/baselines/reference/submoduleAccepted/conformance/plainJSGrammarErrors.errors.txt.diff b/testdata/baselines/reference/submoduleAccepted/conformance/plainJSGrammarErrors.errors.txt.diff
@@ -18,16 +18,7 @@
  plainJSGrammarErrors.js(64,1): error TS1042: 'async' modifier cannot be used here.
  plainJSGrammarErrors.js(65,1): error TS1042: 'async' modifier cannot be used here.
  plainJSGrammarErrors.js(66,1): error TS1042: 'async' modifier cannot be used here.
-@@= skipped -21, +20 lines =@@
- plainJSGrammarErrors.js(93,42): error TS1186: A rest element cannot have an initializer.
- plainJSGrammarErrors.js(96,4): error TS1123: Variable declaration list cannot be empty.
- plainJSGrammarErrors.js(97,9): error TS5076: '||' and '??' operations cannot be mixed without parentheses.
--plainJSGrammarErrors.js(98,9): error TS5076: '??' and '||' operations cannot be mixed without parentheses.
-+plainJSGrammarErrors.js(98,14): error TS5076: '||' and '??' operations cannot be mixed without parentheses.
- plainJSGrammarErrors.js(100,3): error TS1200: Line terminator not permitted before arrow.
- plainJSGrammarErrors.js(102,4): error TS1358: Tagged template expressions are not permitted in an optional chain.
- plainJSGrammarErrors.js(104,6): error TS1171: A comma expression is not allowed in a computed property name.
-@@= skipped -43, +43 lines =@@
+@@= skipped -64, +63 lines =@@
  plainJSGrammarErrors.js(205,36): error TS1325: Argument of dynamic import cannot be spread element.
 
 
@@ -62,15 +53,4 @@
 -!!! error TS8009: The 'async' modifier can only be used in TypeScript files.
      }
      async const cantAsyncConst = 2
-     ~~~~~
-@@= skipped -78, +76 lines =@@
-             ~~~~~~
- !!! error TS5076: '||' and '??' operations cannot be mixed without parentheses.
-     var x = 2 ?? 3 || 4
--            ~~~~~~
--!!! error TS5076: '??' and '||' operations cannot be mixed without parentheses.
-+                 ~~~~~~
-+!!! error TS5076: '||' and '??' operations cannot be mixed without parentheses.
-     const arr = x
-       => x + 1
-       ~~
+     ~~~~~
diff --git a/testdata/baselines/reference/submoduleAccepted/conformance/plainJSGrammarErrors.types.diff b/testdata/baselines/reference/submoduleAccepted/conformance/plainJSGrammarErrors.types.diff
@@ -9,17 +9,7 @@
 
      export { staticParam }
  >staticParam : any
-@@= skipped -97, +97 lines =@@
- var x = 2 ?? 3 || 4
- >x : number
- >2 ?? 3 || 4 : 2 | 3 | 4
-->2 ?? 3 : 2 | 3
- >2 : 2
-+>3 || 4 : 3 | 4
- >3 : 3
- >4 : 4
-
-@@= skipped -194, +194 lines =@@
+@@= skipped -291, +291 lines =@@
  >b : any
 
  switch (b) {
