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Port #62311: Fix parenthesizer rules for binary expressions mixing ?? with ||/&& #2758

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Merged
DanielRosenwasser merged 3 commits into from
Feb 11, 2026
Merged

Port #62311: Fix parenthesizer rules for binary expressions mixing ?? with ||/&& #2758

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e1070fc
Initial plan
Copilot Feb 11, 2026
afba20a
Fix parenthesizer rules for manually constructed binary expressions w…
Copilot Feb 11, 2026
f36d6d2
Fix regression: only parenthesize operator mixing for synthesized nodes
Copilot Feb 11, 2026
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6 changes: 6 additions & 0 deletions internal/printer/printer.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2773,6 +2773,12 @@ func (p *Printer) getBinaryExpressionPrecedence(node *ast.BinaryExpression) (lef

func (p *Printer) emitBinaryExpression(node *ast.BinaryExpression) {
leftPrec, rightPrec := p.getBinaryExpressionPrecedence(node)
if emittedLeft := ast.SkipPartiallyEmittedExpressions(node.Left); ast.NodeIsSynthesized(emittedLeft) && emittedLeft.Kind == ast.KindBinaryExpression && mixingBinaryOperatorsRequiresParentheses(node.OperatorToken.Kind, emittedLeft.AsBinaryExpression().OperatorToken.Kind) {
leftPrec = ast.OperatorPrecedenceHighest
}
if emittedRight := ast.SkipPartiallyEmittedExpressions(node.Right); ast.NodeIsSynthesized(emittedRight) && emittedRight.Kind == ast.KindBinaryExpression && mixingBinaryOperatorsRequiresParentheses(node.OperatorToken.Kind, emittedRight.AsBinaryExpression().OperatorToken.Kind) {
rightPrec = ast.OperatorPrecedenceHighest
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}
state := p.enterNode(node.AsNode())
p.emitExpression(node.Left, leftPrec)
linesBeforeOperator := p.getLinesBetweenNodes(node.AsNode(), node.Left, node.OperatorToken)
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68 changes: 68 additions & 0 deletions internal/printer/printer_test.go
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Expand Up @@ -2517,3 +2517,71 @@ func TestPartiallyEmittedExpression(t *testing.T) {
.expression
.expression;`)
}

func TestParenthesizeBinaryExpressionMixingNullishCoalescing(t *testing.T) {
t.Parallel()

tests := []struct {
title string
innerOp ast.Kind
outerOp ast.Kind
side string
output string
}{
// inner ?? on left side of || or &&
{title: "BarBarWithLeftQuestionQuestion", innerOp: ast.KindQuestionQuestionToken, outerOp: ast.KindBarBarToken, side: "left", output: "(a ?? b) || c;"},
{title: "AmpersandAmpersandWithLeftQuestionQuestion", innerOp: ast.KindQuestionQuestionToken, outerOp: ast.KindAmpersandAmpersandToken, side: "left", output: "(a ?? b) && c;"},
// inner ?? on right side of || or &&
{title: "BarBarWithRightQuestionQuestion", innerOp: ast.KindQuestionQuestionToken, outerOp: ast.KindBarBarToken, side: "right", output: "a || (b ?? c);"},
{title: "AmpersandAmpersandWithRightQuestionQuestion", innerOp: ast.KindQuestionQuestionToken, outerOp: ast.KindAmpersandAmpersandToken, side: "right", output: "a && (b ?? c);"},
// inner || or && on left side of ??
{title: "QuestionQuestionWithLeftBarBar", innerOp: ast.KindBarBarToken, outerOp: ast.KindQuestionQuestionToken, side: "left", output: "(a || b) ?? c;"},
{title: "QuestionQuestionWithLeftAmpersandAmpersand", innerOp: ast.KindAmpersandAmpersandToken, outerOp: ast.KindQuestionQuestionToken, side: "left", output: "(a && b) ?? c;"},
// inner || or && on right side of ??
{title: "QuestionQuestionWithRightBarBar", innerOp: ast.KindBarBarToken, outerOp: ast.KindQuestionQuestionToken, side: "right", output: "a ?? (b || c);"},
{title: "QuestionQuestionWithRightAmpersandAmpersand", innerOp: ast.KindAmpersandAmpersandToken, outerOp: ast.KindQuestionQuestionToken, side: "right", output: "a ?? (b && c);"},
}

for _, tt := range tests {
t.Run(tt.title, func(t *testing.T) {
t.Parallel()
var factory ast.NodeFactory
innerExpr := factory.NewBinaryExpression(
nil, /*modifiers*/
factory.NewIdentifier("a"),
nil, /*typeNode*/
factory.NewToken(tt.innerOp),
factory.NewIdentifier("b"),
)
var outerExpr *ast.Node
if tt.side == "left" {
outerExpr = factory.NewBinaryExpression(
nil, /*modifiers*/
innerExpr, /*left: (a innerOp b)*/
nil, /*typeNode*/
factory.NewToken(tt.outerOp),
factory.NewIdentifier("c"),
)
} else {
outerExpr = factory.NewBinaryExpression(
nil, /*modifiers*/
factory.NewIdentifier("a"),
nil, /*typeNode*/
factory.NewToken(tt.outerOp),
innerExpr, /*right: (b innerOp c)*/
)
// adjust identifiers for right side
innerExpr.AsBinaryExpression().Left = factory.NewIdentifier("b")
innerExpr.AsBinaryExpression().Right = factory.NewIdentifier("c")
}
file := factory.NewSourceFile(ast.SourceFileParseOptions{FileName: "/file.ts", Path: "/file.ts"}, "", factory.NewNodeList(
[]*ast.Node{
factory.NewExpressionStatement(outerExpr),
},
), factory.NewToken(ast.KindEndOfFile))

parsetestutil.MarkSyntheticRecursive(file)
emittestutil.CheckEmit(t, nil, file.AsSourceFile(), tt.output)
})
}
}
10 changes: 10 additions & 0 deletions internal/printer/utilities.go
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Expand Up @@ -625,6 +625,16 @@ func isBinaryOperation(node *ast.Node, token ast.Kind) bool {
node.AsBinaryExpression().OperatorToken.Kind == token
}

func mixingBinaryOperatorsRequiresParentheses(a ast.Kind, b ast.Kind) bool {
if a == ast.KindQuestionQuestionToken {
return b == ast.KindAmpersandAmpersandToken || b == ast.KindBarBarToken
}
if b == ast.KindQuestionQuestionToken {
return a == ast.KindAmpersandAmpersandToken || a == ast.KindBarBarToken
}
return false
}

func isImmediatelyInvokedFunctionExpressionOrArrowFunction(node *ast.Expression) bool {
node = ast.SkipPartiallyEmittedExpressions(node)
if !ast.IsCallExpression(node) {
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