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Merged
merged 1 commit into from
Apr 2, 2025
Merged

Correctly format unsafe expressions. #973

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1 change: 1 addition & 0 deletions Sources/SwiftFormat/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@ add_library(SwiftFormat
Core/SyntaxFormatRule.swift
Core/SyntaxLintRule.swift
Core/SyntaxProtocol+Convenience.swift
Core/SyntaxTraits.swift
Core/Trivia+Convenience.swift
Core/WithAttributesSyntax+Convenience.swift
Core/WithSemicolonSyntax.swift
Expand Down
67 changes: 67 additions & 0 deletions Sources/SwiftFormat/Core/SyntaxTraits.swift
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Original file line number Diff line number Diff line change
@@ -0,0 +1,67 @@
//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

import SwiftSyntax

/// Common protocol implemented by expression syntax types that support calling another expression.
protocol CallingExprSyntaxProtocol: ExprSyntaxProtocol {
var calledExpression: ExprSyntax { get }
}

extension FunctionCallExprSyntax: CallingExprSyntaxProtocol {}
extension SubscriptCallExprSyntax: CallingExprSyntaxProtocol {}

extension Syntax {
func asProtocol(_: CallingExprSyntaxProtocol.Protocol) -> CallingExprSyntaxProtocol? {
return self.asProtocol(SyntaxProtocol.self) as? CallingExprSyntaxProtocol
}
func isProtocol(_: CallingExprSyntaxProtocol.Protocol) -> Bool {
return self.asProtocol(CallingExprSyntaxProtocol.self) != nil
}
}

extension ExprSyntax {
func asProtocol(_: CallingExprSyntaxProtocol.Protocol) -> CallingExprSyntaxProtocol? {
return Syntax(self).asProtocol(SyntaxProtocol.self) as? CallingExprSyntaxProtocol
}
func isProtocol(_: CallingExprSyntaxProtocol.Protocol) -> Bool {
return self.asProtocol(CallingExprSyntaxProtocol.self) != nil
}
}

/// Common protocol implemented by expression syntax types that are expressed as a modified
/// subexpression of the form `<keyword> <subexpr>`.
protocol KeywordModifiedExprSyntaxProtocol: ExprSyntaxProtocol {
var expression: ExprSyntax { get }
}

extension AwaitExprSyntax: KeywordModifiedExprSyntaxProtocol {}
extension TryExprSyntax: KeywordModifiedExprSyntaxProtocol {}
extension UnsafeExprSyntax: KeywordModifiedExprSyntaxProtocol {}

extension Syntax {
func asProtocol(_: KeywordModifiedExprSyntaxProtocol.Protocol) -> KeywordModifiedExprSyntaxProtocol? {
return self.asProtocol(SyntaxProtocol.self) as? KeywordModifiedExprSyntaxProtocol
}
func isProtocol(_: KeywordModifiedExprSyntaxProtocol.Protocol) -> Bool {
return self.asProtocol(KeywordModifiedExprSyntaxProtocol.self) != nil
}
}

extension ExprSyntax {
func asProtocol(_: KeywordModifiedExprSyntaxProtocol.Protocol) -> KeywordModifiedExprSyntaxProtocol? {
return Syntax(self).asProtocol(SyntaxProtocol.self) as? KeywordModifiedExprSyntaxProtocol
}
func isProtocol(_: KeywordModifiedExprSyntaxProtocol.Protocol) -> Bool {
return self.asProtocol(KeywordModifiedExprSyntaxProtocol.self) != nil
}
}
100 changes: 47 additions & 53 deletions Sources/SwiftFormat/PrettyPrint/TokenStreamCreator.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -1068,14 +1068,12 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {

if let calledMemberAccessExpr = node.calledExpression.as(MemberAccessExprSyntax.self) {
if let base = calledMemberAccessExpr.base, base.is(DeclReferenceExprSyntax.self) {
// When this function call is wrapped by a try-expr or await-expr, the group applied when
// visiting that wrapping expression is sufficient. Adding another group here in that case
// can result in unnecessarily breaking after the try/await keyword.
if !(base.firstToken(viewMode: .sourceAccurate)?.previousToken(viewMode: .all)?.parent?.is(TryExprSyntax.self)
?? false
|| base.firstToken(viewMode: .sourceAccurate)?.previousToken(viewMode: .all)?.parent?.is(AwaitExprSyntax.self)
?? false)
{
// When this function call is wrapped by a keyword-modified expression, the group applied
// when visiting that wrapping expression is sufficient. Adding another group here in that
// case can result in unnecessarily breaking after the modifier keyword.
if !(base.firstToken(viewMode: .sourceAccurate)?.previousToken(viewMode: .all)?.parent?.isProtocol(
KeywordModifiedExprSyntaxProtocol.self
) ?? false) {
before(base.firstToken(viewMode: .sourceAccurate), tokens: .open)
after(calledMemberAccessExpr.declName.baseName.lastToken(viewMode: .sourceAccurate), tokens: .close)
}
Expand Down Expand Up @@ -1780,8 +1778,11 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
tokens: .break(.continue, newlines: .elective(ignoresDiscretionary: true))
)

// Check for an anchor token inside of the expression to group with the try keyword.
if let anchorToken = findTryAwaitExprConnectingToken(inExpr: node.expression) {
// Check for an anchor token inside of the expression to end a group starting with the `try`
// keyword.
if !(node.parent?.isProtocol(KeywordModifiedExprSyntaxProtocol.self) ?? false),
let anchorToken = connectingTokenForKeywordModifiedExpr(inSubExpr: node.expression)
{
before(node.tryKeyword, tokens: .open)
after(anchorToken, tokens: .close)
}
Expand All @@ -1795,9 +1796,10 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
tokens: .break(.continue, newlines: .elective(ignoresDiscretionary: true))
)

// Check for an anchor token inside of the expression to group with the await keyword.
if !(node.parent?.is(TryExprSyntax.self) ?? false),
let anchorToken = findTryAwaitExprConnectingToken(inExpr: node.expression)
// Check for an anchor token inside of the expression to end a group starting with the `await`
// keyword.
if !(node.parent?.isProtocol(KeywordModifiedExprSyntaxProtocol.self) ?? false),
let anchorToken = connectingTokenForKeywordModifiedExpr(inSubExpr: node.expression)
{
before(node.awaitKeyword, tokens: .open)
after(anchorToken, tokens: .close)
Expand All @@ -1806,18 +1808,37 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
return .visitChildren
}

/// Searches the AST from `expr` to find a token that should be grouped with an enclosing
/// try-expr or await-expr. Returns that token, or nil when no such token is found.
override func visit(_ node: UnsafeExprSyntax) -> SyntaxVisitorContinueKind {
// Unlike `try` and `await`, `unsafe` is a contextual keyword that may not be separated from
// the following token by a line break. Keep them glued together with `.space`.
before(node.expression.firstToken(viewMode: .sourceAccurate), tokens: .space)

// Check for an anchor token inside of the expression to end a group starting with the `unsafe`
// keyword.
if !(node.parent?.isProtocol(KeywordModifiedExprSyntaxProtocol.self) ?? false),
let anchorToken = connectingTokenForKeywordModifiedExpr(inSubExpr: node.expression)
{
before(node.unsafeKeyword, tokens: .open)
after(anchorToken, tokens: .close)
}

return .visitChildren
}

/// Searches within a subexpression of a keyword-modified expression to find the last token in a
/// range that should be grouped with the leading keyword modifier.
///
/// - Parameter expr: An expression that is wrapped by a try-expr or await-expr.
/// - Returns: A token that should be grouped with the try-expr or await-expr, or nil.
func findTryAwaitExprConnectingToken(inExpr expr: ExprSyntax) -> TokenSyntax? {
if let awaitExpr = expr.as(AwaitExprSyntax.self) {
// If we were called from the `try` of a `try await <expr>`, drill into the child expression.
return findTryAwaitExprConnectingToken(inExpr: awaitExpr.expression)
/// - Parameter expr: An expression that is wrapped by a keyword-modified expression.
/// - Returns: The token that should end the group that is started by the modifier keyword, or
/// nil if there should be no group.
func connectingTokenForKeywordModifiedExpr(inSubExpr expr: ExprSyntax) -> TokenSyntax? {
if let modifiedExpr = expr.asProtocol(KeywordModifiedExprSyntaxProtocol.self) {
// If we were called from a keyword-modified expression like `try`, `await`, or `unsafe`,
// recursively drill into the child expression.
return connectingTokenForKeywordModifiedExpr(inSubExpr: modifiedExpr.expression)
}
if let callingExpr = expr.asProtocol(CallingExprSyntaxProtocol.self) {
return findTryAwaitExprConnectingToken(inExpr: callingExpr.calledExpression)
return connectingTokenForKeywordModifiedExpr(inSubExpr: callingExpr.calledExpression)
}
if let memberAccessExpr = expr.as(MemberAccessExprSyntax.self), let base = memberAccessExpr.base {
// When there's a simple base (i.e. identifier), group the entire `try/await <base>.<name>`
Expand All @@ -1826,7 +1847,7 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
if base.is(DeclReferenceExprSyntax.self) {
return memberAccessExpr.declName.baseName.lastToken(viewMode: .sourceAccurate)
}
return findTryAwaitExprConnectingToken(inExpr: base)
return connectingTokenForKeywordModifiedExpr(inSubExpr: base)
}
if expr.is(DeclReferenceExprSyntax.self) {
return expr.lastToken(viewMode: .sourceAccurate)
Expand Down Expand Up @@ -3825,13 +3846,12 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
/// that are known to wrap an expression, e.g. try expressions, are handled by checking the
/// expression that they contain.
private func isCompoundExpression(_ expr: ExprSyntax) -> Bool {
if let modifiedExpr = expr.asProtocol(KeywordModifiedExprSyntaxProtocol.self) {
return isCompoundExpression(modifiedExpr.expression)
}
switch Syntax(expr).as(SyntaxEnum.self) {
case .awaitExpr(let awaitExpr):
return isCompoundExpression(awaitExpr.expression)
case .infixOperatorExpr, .ternaryExpr, .isExpr, .asExpr:
return true
case .tryExpr(let tryExpr):
return isCompoundExpression(tryExpr.expression)
case .tupleExpr(let tupleExpr) where tupleExpr.elements.count == 1:
return isCompoundExpression(tupleExpr.elements.first!.expression)
default:
Expand Down Expand Up @@ -4505,29 +4525,3 @@ extension NewlineBehavior {
}
}
}

/// Common protocol implemented by expression syntax types that support calling another expression.
protocol CallingExprSyntaxProtocol: ExprSyntaxProtocol {
var calledExpression: ExprSyntax { get }
}

extension FunctionCallExprSyntax: CallingExprSyntaxProtocol {}
extension SubscriptCallExprSyntax: CallingExprSyntaxProtocol {}

extension Syntax {
func asProtocol(_: CallingExprSyntaxProtocol.Protocol) -> CallingExprSyntaxProtocol? {
return self.asProtocol(SyntaxProtocol.self) as? CallingExprSyntaxProtocol
}
func isProtocol(_: CallingExprSyntaxProtocol.Protocol) -> Bool {
return self.asProtocol(CallingExprSyntaxProtocol.self) != nil
}
}

extension ExprSyntax {
func asProtocol(_: CallingExprSyntaxProtocol.Protocol) -> CallingExprSyntaxProtocol? {
return Syntax(self).asProtocol(SyntaxProtocol.self) as? CallingExprSyntaxProtocol
}
func isProtocol(_: CallingExprSyntaxProtocol.Protocol) -> Bool {
return self.asProtocol(CallingExprSyntaxProtocol.self) != nil
}
}
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