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Rewrite redundant_type_annotation with SwiftSyntax (#5389)
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Co-authored-by: Danny Mösch <danny.moesch@icloud.com>
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@tonell-m @SimplyDanny
tonell-m and SimplyDanny committed Apr 21, 2024
1 parent 5315c3d commit b3dd890
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Showing 4 changed files with 208 additions and 78 deletions.
8 changes: 8 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,12 @@
[Muhammad Zeeshan](https://github.com/mzeeshanid)
[#2802](https://github.com/realm/SwiftLint/issues/2802)

* Add new `ignore_attributes` option to `redundant_type_annotation` rule
that allows disabling the rule for properties that are marked with at least
one of the configured attributes.
[tonell-m](https://github.com/tonell-m)
[#5366](https://github.com/realm/SwiftLint/issues/5366)

* Rewrite the following rules with SwiftSyntax:
* `explicit_acl`
* `extension_access_modifier`
Expand All @@ -83,6 +89,7 @@
* `nimble_operator`
* `opening_brace`
* `orphaned_doc_comment`
* `redundant_type_annotation`
* `trailing_closure`
* `void_return`

Expand All @@ -91,6 +98,7 @@
[Marcelo Fabri](https://github.com/marcelofabri)
[swiftty](https://github.com/swiftty)
[KS1019](https://github.com/KS1019)
[tonell-m](https://github.com/tonell-m)

* Print invalid keys when configuration parsing fails.
[SimplyDanny](https://github.com/SimplyDanny)
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266 changes: 188 additions & 78 deletions Source/SwiftLintBuiltInRules/Rules/Idiomatic/RedundantTypeAnnotationRule.swift
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Original file line number Diff line number Diff line change
@@ -1,8 +1,9 @@
import Foundation
import SourceKittenFramework
import SwiftLintCore
import SwiftSyntax

struct RedundantTypeAnnotationRule: OptInRule, SubstitutionCorrectableRule {
var configuration = SeverityConfiguration<Self>(.warning)
@SwiftSyntaxRule
struct RedundantTypeAnnotationRule: OptInRule, SwiftSyntaxCorrectableRule {
var configuration = RedundantTypeAnnotationConfiguration()

static let description = RuleDescription(
identifier: "redundant_type_annotation",
Expand All @@ -12,7 +13,23 @@ struct RedundantTypeAnnotationRule: OptInRule, SubstitutionCorrectableRule {
nonTriggeringExamples: [
Example("var url = URL()"),
Example("var url: CustomStringConvertible = URL()"),
Example("@IBInspectable var color: UIColor = UIColor.white"),
Example("var one: Int = 1, two: Int = 2, three: Int"),
Example("guard let url = URL() else { return }"),
Example("if let url = URL() { return }"),
Example("let alphanumerics = CharacterSet.alphanumerics"),
Example("var set: Set<Int> = Set([])"),
Example("var set: Set<Int> = Set.init([])"),
Example("var set = Set<Int>([])"),
Example("var set = Set<Int>.init([])"),
Example("guard var set: Set<Int> = Set([]) else { return }"),
Example("if var set: Set<Int> = Set.init([]) { return }"),
Example("guard var set = Set<Int>([]) else { return }"),
Example("if var set = Set<Int>.init([]) { return }"),
Example("var one: A<T> = B()"),
Example("var one: A = B<T>()"),
Example("var one: A<T> = B<T>()"),
Example("let a = A.b.c.d"),
Example("let a: B = A.b.c.d"),
Example("""
enum Direction {
case up
Expand All @@ -28,15 +45,38 @@ struct RedundantTypeAnnotationRule: OptInRule, SubstitutionCorrectableRule {
}
var direction = Direction.up
""")
"""),
Example("@IgnoreMe var a: Int = Int(5)", configuration: ["ignore_attributes": ["IgnoreMe"]]),
Example("""
var a: Int {
@IgnoreMe let i: Int = Int(1)
return i
}
""", configuration: ["ignore_attributes": ["IgnoreMe"]])
],
triggeringExamples: [
Example("var url↓:URL=URL()"),
Example("var url↓:URL = URL(string: \"\")"),
Example("var url↓: URL = URL()"),
Example("let url↓: URL = URL()"),
Example("lazy var url↓: URL = URL()"),
Example("let url↓: URL = URL()!"),
Example("var one: Int = 1, two↓: Int = Int(5), three: Int"),
Example("guard let url↓: URL = URL() else { return }"),
Example("if let url↓: URL = URL() { return }"),
Example("let alphanumerics↓: CharacterSet = CharacterSet.alphanumerics"),
Example("var set↓: Set<Int> = Set<Int>([])"),
Example("var set↓: Set<Int> = Set<Int>.init([])"),
Example("var set↓: Set = Set<Int>([])"),
Example("var set↓: Set = Set<Int>.init([])"),
Example("guard var set↓: Set = Set<Int>([]) else { return }"),
Example("if var set↓: Set = Set<Int>.init([]) { return }"),
Example("guard var set↓: Set<Int> = Set<Int>([]) else { return }"),
Example("if var set↓: Set<Int> = Set<Int>.init([]) { return }"),
Example("var set↓: Set = Set<Int>([]), otherSet: Set<Int>"),
Example("var num↓: Int = Int.random(0..<10)"),
Example("let a↓: A = A.b.c.d"),
Example("let a↓: A = A.f().b"),
Example("""
class ViewController: UIViewController {
func someMethod() {
Expand All @@ -52,13 +92,43 @@ struct RedundantTypeAnnotationRule: OptInRule, SubstitutionCorrectableRule {
}
var direction↓: Direction = Direction.up
""")
"""),
Example("@DontIgnoreMe var a↓: Int = Int(5)", configuration: ["ignore_attributes": ["IgnoreMe"]]),
Example("""
@IgnoreMe
var a: Int {
let i↓: Int = Int(1)
return i
}
""", configuration: ["ignore_attributes": ["IgnoreMe"]])
],
corrections: [
Example("var url↓: URL = URL()"): Example("var url = URL()"),
Example("let url↓: URL = URL()"): Example("let url = URL()"),
Example("var one: Int = 1, two↓: Int = Int(5), three: Int"):
Example("var one: Int = 1, two = Int(5), three: Int"),
Example("guard let url↓: URL = URL() else { return }"):
Example("guard let url = URL() else { return }"),
Example("if let url↓: URL = URL() { return }"):
Example("if let url = URL() { return }"),
Example("let alphanumerics↓: CharacterSet = CharacterSet.alphanumerics"):
Example("let alphanumerics = CharacterSet.alphanumerics"),
Example("var set↓: Set<Int> = Set<Int>([])"):
Example("var set = Set<Int>([])"),
Example("var set↓: Set<Int> = Set<Int>.init([])"):
Example("var set = Set<Int>.init([])"),
Example("var set↓: Set = Set<Int>([])"):
Example("var set = Set<Int>([])"),
Example("var set↓: Set = Set<Int>.init([])"):
Example("var set = Set<Int>.init([])"),
Example("guard var set↓: Set<Int> = Set<Int>([]) else { return }"):
Example("guard var set = Set<Int>([]) else { return }"),
Example("if var set↓: Set<Int> = Set<Int>.init([]) { return }"):
Example("if var set = Set<Int>.init([]) { return }"),
Example("var set↓: Set = Set<Int>([]), otherSet: Set<Int>"):
Example("var set = Set<Int>([]), otherSet: Set<Int>"),
Example("let a↓: A = A.b.c.d"):
Example("let a = A.b.c.d"),
Example("""
class ViewController: UIViewController {
func someMethod() {
Expand All @@ -72,97 +142,137 @@ struct RedundantTypeAnnotationRule: OptInRule, SubstitutionCorrectableRule {
let myVar = Int(5)
}
}
"""),
Example("var num: Int = Int.random(0..<10)"): Example("var num = Int.random(0..<10)"),
Example("""
@IgnoreMe
var a: Int {
let i↓: Int = Int(1)
return i
}
""", configuration: ["ignore_attributes": ["IgnoreMe"]]):
Example("""
@IgnoreMe
var a: Int {
let i = Int(1)
return i
}
""")
]
)
}

func validate(file: SwiftLintFile) -> [StyleViolation] {
return violationRanges(in: file).map { range in
StyleViolation(
ruleDescription: Self.description,
severity: configuration.severity,
location: Location(file: file, characterOffset: range.location)
)
private extension RedundantTypeAnnotationRule {
final class Visitor: ViolationsSyntaxVisitor<ConfigurationType> {
override func visitPost(_ node: PatternBindingSyntax) {
if node.parentDoesNotContainIgnoredAttributes(for: configuration),
let typeAnnotation = node.typeAnnotation,
let initializer = node.initializer?.value,
typeAnnotation.isRedundant(with: initializer) {
violations.append(typeAnnotation.positionAfterSkippingLeadingTrivia)
violationCorrections.append(ViolationCorrection(
start: typeAnnotation.position,
end: typeAnnotation.endPositionBeforeTrailingTrivia,
replacement: ""
))
}
}
}

func substitution(for violationRange: NSRange, in file: SwiftLintFile) -> (NSRange, String)? {
return (violationRange, "")
override func visitPost(_ node: OptionalBindingConditionSyntax) {
if let typeAnnotation = node.typeAnnotation,
let initializer = node.initializer?.value,
typeAnnotation.isRedundant(with: initializer) {
violations.append(typeAnnotation.positionAfterSkippingLeadingTrivia)
violationCorrections.append(ViolationCorrection(
start: typeAnnotation.position,
end: typeAnnotation.endPositionBeforeTrailingTrivia,
replacement: ""
))
}
}
}
}

private let typeAnnotationPattern: String
private let expressionPattern: String

init() {
typeAnnotationPattern =
":\\s*" + // semicolon and any number of whitespaces
"\\w+" // type name

expressionPattern =
"(var|let)" + // var or let
"\\s+" + // at least single whitespace
"\\w+" + // variable name
"\\s*" + // possible whitespaces
typeAnnotationPattern +
"\\s*=\\s*" + // assignment operator with possible surrounding whitespaces
"\\w+" + // assignee name (type or keyword)
"[\\(\\.]?" // possible opening parenthesis or dot
}
private extension TypeAnnotationSyntax {
func isRedundant(with initializerExpr: ExprSyntax) -> Bool {
// Extract type and type name from type annotation
guard let type = type.as(IdentifierTypeSyntax.self) else {
return false
}
let typeName = type.trimmedDescription

func violationRanges(in file: SwiftLintFile) -> [NSRange] {
return file
.match(pattern: expressionPattern)
.filter {
$0.1 == [.keyword, .identifier, .typeidentifier, .identifier] ||
$0.1 == [.keyword, .identifier, .typeidentifier, .keyword]
}
.filter { !isFalsePositive(file: file, range: $0.0) }
.filter { !isIBInspectable(file: file, range: $0.0) }
.compactMap {
file.match(pattern: typeAnnotationPattern,
excludingSyntaxKinds: SyntaxKind.commentAndStringKinds, range: $0.0).first
}
}
var initializer = initializerExpr
if let forceUnwrap = initializer.as(ForceUnwrapExprSyntax.self) {
initializer = forceUnwrap.expression
}

private func isFalsePositive(file: SwiftLintFile, range: NSRange) -> Bool {
guard let typeNames = getPartsOfExpression(in: file, range: range) else { return false }
// If the initializer is a boolean expression, we consider using the `Bool` type
// annotation as redundant.
if initializer.is(BooleanLiteralExprSyntax.self) {
return typeName == "Bool"
}

let lhs = typeNames.variableTypeName
let rhs = typeNames.assigneeName
// If the initializer is a function call (generally a constructor or static builder),
// check if the base type is the same as the one from the type annotation.
if let functionCall = initializer.as(FunctionCallExprSyntax.self) {
if let calledExpression = functionCall.calledExpression.as(DeclReferenceExprSyntax.self) {
return calledExpression.baseName.text == typeName
}
// Parse generic arguments in the intializer if there are any (e.g. var s = Set<Int>(...))
if let genericSpecialization = functionCall.calledExpression.as(GenericSpecializationExprSyntax.self) {
// In this case it should be considered redundant if the type name is the same in the type annotation
// E.g. var s: Set = Set<Int>() should trigger a violation
return genericSpecialization.expression.trimmedDescription == type.typeName
}

if lhs == rhs || (lhs == "Bool" && (rhs == "true" || rhs == "false")) {
return false
// If the function call is a member access expression, check if it is a violation
return isMemberAccessViolation(node: functionCall.calledExpression, type: type)
}
return true
}

private func getPartsOfExpression(
in file: SwiftLintFile, range: NSRange
) -> (variableTypeName: String, assigneeName: String)? {
let substring = file.stringView.substring(with: range)
let components = substring.components(separatedBy: "=")
// If the initializer is a member access, check if the base type name is the same as
// the type annotation
return isMemberAccessViolation(node: initializer, type: type)
}

guard
components.count == 2,
let variableTypeName = components[0].components(separatedBy: ":").last?.trimmingCharacters(in: .whitespaces)
/// Checks if the given node is a member access (i.e. an enum case or a static property or function)
/// and if so checks if the base type is the same as the given type name.
private func isMemberAccessViolation(node: ExprSyntax, type: IdentifierTypeSyntax) -> Bool {
guard let memberAccess = node.as(MemberAccessExprSyntax.self),
let base = memberAccess.base
else {
return nil
// If the type is implicit, `base` will be nil, meaning there is no redundancy.
return false
}

let charactersToTrimFromRhs = CharacterSet(charactersIn: ".(").union(.whitespaces)
let assigneeName = components[1].trimmingCharacters(in: charactersToTrimFromRhs)
// Parse generic arguments in the intializer if there are any (e.g. var s = Set<Int>(...))
if let genericSpecialization = base.as(GenericSpecializationExprSyntax.self) {
// In this case it should be considered redundant if the type name is the same in the type annotation
// E.g. var s: Set = Set<Int>() should trigger a violation
return genericSpecialization.expression.trimmedDescription == type.typeName
}

return (variableTypeName, assigneeName)
// In the case of chained MemberAccessExprSyntax (e.g. let a: A = A.b.c), call this function recursively
// with the base sequence as root node (in this case A.b).
if base.is(MemberAccessExprSyntax.self) {
return isMemberAccessViolation(node: base, type: type)
}
// Same for FunctionCallExprSyntax ...
if let call = base.as(FunctionCallExprSyntax.self) {
return isMemberAccessViolation(node: call.calledExpression, type: type)
}
return base.trimmedDescription == type.trimmedDescription
}
}

private func isIBInspectable(file: SwiftLintFile, range: NSRange) -> Bool {
guard
let byteRange = file.stringView.NSRangeToByteRange(start: range.location, length: range.length),
let dict = file.structureDictionary.structures(forByteOffset: byteRange.location).last,
let kind = dict.declarationKind,
SwiftDeclarationKind.variableKinds.contains(kind)
else { return false }

return dict.enclosedSwiftAttributes.contains(.ibinspectable)
private extension PatternBindingSyntax {
/// Checks if none of the attributes flagged as ignored in the configuration
/// are set for this node's parent's parent, if it's a variable declaration
func parentDoesNotContainIgnoredAttributes(for configuration: RedundantTypeAnnotationConfiguration) -> Bool {
guard let variableDecl = parent?.parent?.as(VariableDeclSyntax.self) else {
return true
}
return configuration.ignoreAttributes.allSatisfy {
!variableDecl.attributes.contains(attributeNamed: $0)
}
}
}
11 changes: 11 additions & 0 deletions ...SwiftLintBuiltInRules/Rules/RuleConfigurations/RedundantTypeAnnotationConfiguration.swift
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Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
import SwiftLintCore

@AutoApply
struct RedundantTypeAnnotationConfiguration: SeverityBasedRuleConfiguration {
typealias Parent = RedundantTypeAnnotationRule

@ConfigurationElement(key: "severity")
var severityConfiguration = SeverityConfiguration<Parent>(.warning)
@ConfigurationElement(key: "ignore_attributes")
var ignoreAttributes = Set<String>(["IBInspectable"])
}
1 change: 1 addition & 0 deletions Tests/IntegrationTests/default_rule_configurations.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -456,6 +456,7 @@ redundant_string_enum_value:
severity: warning
redundant_type_annotation:
severity: warning
ignore_attributes: ["IBInspectable"]
redundant_void_return:
severity: warning
include_closures: true
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