RedundantTypeAnnotation: add 'ignore_type_interfaces' option

CHANGELOG.md

@@ -21,6 +21,13 @@
   argument `--use-script-input-file-lists`.  
   [BlueVirusX](https://github.com/BlueVirusX)
 
+* The `redundant_type_annotation` rule gains a new option,
+  `ignore_type_interfaces`, that skips enforcement on members in a
+  type declaration (like a `struct`). This helps the rule coexist with
+  the `explicit_type_interface` rule that requires such redundancy.
+  [jaredgrubb](https://github.com/jaredgrubb)
+  [#3750](https://github.com/realm/SwiftLint/issues/3750)
+
 #### Bug Fixes
 
 * Run command plugin in whole package if no targets are defined in the

Source/SwiftLintBuiltInRules/Rules/Idiomatic/RedundantTypeAnnotationRule.swift

@@ -57,6 +57,12 @@ struct RedundantTypeAnnotationRule: OptInRule, SwiftSyntaxCorrectableRule {
             Example("var dbl: Double = 0.0"),
             Example("var int: Int = 0"),
             Example("var str: String = \"str\""),
+            Example("""
+            struct Foo {
+                var url: URL = URL()
+                let myVar: Int? = 0, s: String = ""
+            }
+            """, configuration: ["ignore_type_interfaces": true]),
         ],
         triggeringExamples: [
             Example("var url↓:URL=URL()"),
@@ -88,6 +94,13 @@ struct RedundantTypeAnnotationRule: OptInRule, SwiftSyntaxCorrectableRule {
               }
             }
             """),
+            Example("""
+            class ViewController: UIViewController {
+              func someMethod() {
+                let myVar↓: Int = Int(5)
+              }
+            }
+            """, configuration: ["ignore_type_interfaces": true]),
             Example("let a↓: [Int] = [Int]()"),
             Example("let a↓: A.B = A.B()"),
             Example("""
@@ -183,7 +196,7 @@ private extension RedundantTypeAnnotationRule {
     final class Visitor: ViolationsSyntaxVisitor<ConfigurationType> {
         override func visitPost(_ node: PatternBindingSyntax) {
             if let varDecl = node.parent?.parent?.as(VariableDeclSyntax.self),
-               configuration.ignoreAttributes.allSatisfy({ !varDecl.attributes.contains(attributeNamed: $0) }),
+               !configuration.shouldSkipRuleCheck(for: varDecl),
                let typeAnnotation = node.typeAnnotation,
                let initializer = node.initializer?.value {
                 collectViolation(forType: typeAnnotation, withInitializer: initializer)
@@ -261,3 +274,17 @@ private extension SyntaxKind {
         }
     }
 }
+
+extension RedundantTypeAnnotationConfiguration {
+    func shouldSkipRuleCheck(for varDecl: VariableDeclSyntax) -> Bool {
+        if ignoreAttributes.contains(where: { varDecl.attributes.contains(attributeNamed: $0) }) {
+            return true
+        }
+        if ignoreTypeInterfaces,
+           let parentNode = varDecl.parent,
+           parentNode.as(CodeBlockItemSyntax.self) == nil {
+            return true
+        }
+        return false
+    }
+}

Source/SwiftLintBuiltInRules/Rules/RuleConfigurations/RedundantTypeAnnotationConfiguration.swift

@@ -8,6 +8,8 @@ struct RedundantTypeAnnotationConfiguration: SeverityBasedRuleConfiguration {
     var severityConfiguration = SeverityConfiguration<Parent>(.warning)
     @ConfigurationElement(key: "ignore_attributes")
     var ignoreAttributes = Set<String>(["IBInspectable"])
+    @ConfigurationElement(key: "ignore_type_interfaces")
+    private(set) var ignoreTypeInterfaces = false
     @ConfigurationElement(key: "consider_default_literal_types_redundant")
     private(set) var considerDefaultLiteralTypesRedundant = false
 }

Tests/IntegrationTests/default_rule_configurations.yml

@@ -473,6 +473,7 @@ redundant_string_enum_value:
 redundant_type_annotation:
   severity: warning
   ignore_attributes: ["IBInspectable"]
+  ignore_type_interfaces: false
   consider_default_literal_types_redundant: false
 redundant_void_return:
   severity: warning