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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2019 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
/// Force-unwraps are strongly discouraged and must be documented.
///
/// This rule does not apply to test code, defined as code which:
/// * Contains the line `import XCTest`
///
/// Lint: If a force unwrap is used, a lint warning is raised.
@_spi(Rules)
public final class NeverForceUnwrap: SyntaxLintRule {
/// Identifies this rule as being opt-in. While force unwrap is an unsafe pattern (i.e. it can
/// crash), there are valid contexts for force unwrap where it won't crash. This rule can't
/// evaluate the context around the force unwrap to make that determination.
public override class var isOptIn: Bool { return true }
public override func visit(_ node: SourceFileSyntax) -> SyntaxVisitorContinueKind {
// Tracks whether "XCTest" is imported in the source file before processing individual nodes.
setImportsXCTest(context: context, sourceFile: node)
return .visitChildren
}
public override func visit(_ node: ForceUnwrapExprSyntax) -> SyntaxVisitorContinueKind {
guard context.importsXCTest == .doesNotImportXCTest else { return .skipChildren }
diagnose(.doNotForceUnwrap(name: node.expression.trimmedDescription), on: node)
return .skipChildren
}
public override func visit(_ node: AsExprSyntax) -> SyntaxVisitorContinueKind {
// Only fire if we're not in a test file and if there is an exclamation mark following the `as`
// keyword.
guard context.importsXCTest == .doesNotImportXCTest else { return .skipChildren }
guard let questionOrExclamation = node.questionOrExclamationMark else { return .skipChildren }
guard questionOrExclamation.tokenKind == .exclamationMark else { return .skipChildren }
diagnose(.doNotForceCast(name: node.type.trimmedDescription), on: node)
return .skipChildren
}
}
extension Finding.Message {
fileprivate static func doNotForceUnwrap(name: String) -> Finding.Message {
"do not force unwrap '\(name)'"
}
fileprivate static func doNotForceCast(name: String) -> Finding.Message {
"do not force cast to '\(name)'"
}
}
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