Don't trigger on if case statements

CHANGELOG.md

@@ -60,6 +60,9 @@
   [Marcelo Fabri](https://github.com/marcelofabri)
   [#2851](https://github.com/realm/SwiftLint/issues/2851)
 
+* Don't trigger `explicit_type_interface` on `if case let` statements.
+  [Carlos Millani](https://github.com/cmillani)
+
 ## 0.34.0: Anti-Static Wool Dryer Balls
 
 #### Breaking

Source/SwiftLintFramework/Models/MasterRuleList.swift

@@ -1,4 +1,4 @@
-// Generated using Sourcery 0.16.1 — https://github.com/krzysztofzablocki/Sourcery
+// Generated using Sourcery 0.16.2 — https://github.com/krzysztofzablocki/Sourcery
 // DO NOT EDIT
 
 public let masterRuleList = RuleList(rules: [

Source/SwiftLintFramework/Rules/Idiomatic/ExplicitTypeInterfaceRule.swift

@@ -95,6 +95,7 @@ public struct ExplicitTypeInterfaceRule: OptInRule, ConfigurationProviderRule {
             (!configuration.allowRedundancy ||
                 (!dictionary.isInitCall(file: file) && !dictionary.isTypeReferenceAssignment(file: file))
             ),
+            !dictionary.isIfCaseCall(file: file, parentStructure: parentStructure),
             !parentStructure.contains([.forEach, .guard]),
             !parentStructure.caseStatementPatternRanges.contains(offset),
             !parentStructure.caseExpressionRanges.contains(offset),
@@ -115,6 +116,20 @@ private extension Dictionary where Key == String, Value == SourceKitRepresentabl
         return typeName != nil
     }
 
+    func isIfCaseCall(file: File, parentStructure: [String: SourceKitRepresentable]) -> Bool {
+        guard parentStructure.kind == SwiftExpressionKind.call.rawValue,
+            let parentOffset = parentStructure.offset,
+            case let contents = file.contents.bridge(),
+            let beforeParentRange = contents.byteRangeToNSRange(start: parentOffset, length: 0) else {
+            return false
+        }
+
+        let fileUpToParent = contents.substring(to: beforeParentRange.location)
+        let isCaseRegex = regex("if\\s+case\\s+(let|var)?\\s*$")
+
+        return isCaseRegex.firstMatch(in: fileUpToParent, options: [], range: fileUpToParent.fullNSRange) != nil
+    }
+
     func isInitCall(file: File) -> Bool {
         guard
             let nameOffset = nameOffset,

Tests/SwiftLintFrameworkTests/ExplicitTypeInterfaceRuleTests.swift

@@ -178,6 +178,17 @@ class ExplicitTypeInterfaceRuleTests: XCTestCase {
                 case var (x, y): break
                 }
             }
+            """,
+            """
+            enum Foo {
+              case caseOne(propOne: Int)
+            }
+
+            let testA: Foo = .caseOne(propOne: 2)
+
+            if case let Foo.caseOne(propOne) = testA { }
+
+            if case Foo.caseOne(let propOne) = testA { }
             """
         ]