From 6ec5806a936950a51d3eede098f7a1591c3475fc Mon Sep 17 00:00:00 2001
From: Marcelo Fabri <me@marcelofabri.com>
Date: Wed, 5 Aug 2020 00:42:27 -0700
Subject: [PATCH] Trigger closure_parameter_position in free closures and
 capture lists

---
 CHANGELOG.md                                  |  5 ++
 .../Style/ClosureParameterPositionRule.swift  | 80 ++++++++++++++++---
 2 files changed, 75 insertions(+), 10 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ccbc4bfc2a..b2804f34f9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -59,6 +59,11 @@
   [Marcelo Fabri](https://github.com/marcelofabri)
   [#3186](https://github.com/realm/SwiftLint/issues/3186)
 
+* `closure_parameter_position` now triggers in closures that are not inside a
+  function call and also validates captured variables.  
+  [Marcelo Fabri](https://github.com/marcelofabri)
+  [#3225](https://github.com/realm/SwiftLint/issues/3225)
+
 ## 0.39.2: Stay Home
 
 This is the last release to support building with Swift 5.0.x.
diff --git a/Source/SwiftLintFramework/Rules/Style/ClosureParameterPositionRule.swift b/Source/SwiftLintFramework/Rules/Style/ClosureParameterPositionRule.swift
index bb202e03a2..f01da2a670 100644
--- a/Source/SwiftLintFramework/Rules/Style/ClosureParameterPositionRule.swift
+++ b/Source/SwiftLintFramework/Rules/Style/ClosureParameterPositionRule.swift
@@ -34,22 +34,81 @@ public struct ClosureParameterPositionRule: ASTRule, ConfigurationProviderRule,
             """)
         ],
         triggeringExamples: [
-            Example("[1, 2].map {\n ↓number in\n number + 1 \n}\n"),
-            Example("[1, 2].map {\n ↓number -> Int in\n number + 1 \n}\n"),
-            Example("[1, 2].map {\n (↓number: Int) -> Int in\n number + 1 \n}\n"),
-            Example("[1, 2].map {\n [weak self] ↓number in\n number + 1 \n}\n"),
-            Example("[1, 2].map { [weak self]\n ↓number in\n number + 1 \n}\n"),
-            Example("[1, 2].map({\n ↓number in\n number + 1 \n})\n"),
-            Example("[1, 2].something(closure: {\n ↓number in\n number + 1 \n})\n"),
-            Example("[1, 2].reduce(0) {\n ↓sum, ↓number in\n number + sum \n}\n")
+            Example("""
+            [1, 2].map {
+                ↓number in
+                number + 1
+            }
+            """),
+            Example("""
+            [1, 2].map {
+                ↓number -> Int in
+                number + 1
+            }
+            """),
+            Example("""
+            [1, 2].map {
+                (↓number: Int) -> Int in
+                number + 1
+            }
+            """),
+            Example("""
+            [1, 2].map {
+                [weak ↓self] ↓number in
+                number + 1
+            }
+            """),
+            Example("""
+            [1, 2].map { [weak self]
+                ↓number in
+                number + 1
+            }
+            """),
+            Example("""
+            [1, 2].map({
+                ↓number in
+                number + 1
+            })
+            """),
+            Example("""
+            [1, 2].something(closure: {
+                ↓number in
+                number + 1
+            })
+            """),
+            Example("""
+            [1, 2].reduce(0) {
+                ↓sum, ↓number in
+                number + sum
+            })
+            """),
+            Example("""
+            f.completionHandler = {
+                ↓thing in
+                doStuff()
+            }
+            """),
+            Example("""
+            foo {
+                [weak ↓self] in
+                self?.bar()
+            }
+            """)
         ]
     )
 
     private static let openBraceRegex = regex("\\{")
 
+    public func validate(file: SwiftLintFile) -> [StyleViolation] {
+        return file.structureDictionary.traverseDepthFirst { subDict in
+            guard let kind = self.kind(from: subDict) else { return nil }
+            return validate(file: file, kind: kind, dictionary: subDict)
+        }.unique.sorted(by: { $0.location < $1.location })
+    }
+
     public func validate(file: SwiftLintFile, kind: SwiftExpressionKind,
                          dictionary: SourceKittenDictionary) -> [StyleViolation] {
-        guard kind == .call else {
+        guard kind == .closure || kind == .call else {
             return []
         }
 
@@ -61,7 +120,8 @@ public struct ClosureParameterPositionRule: ASTRule, ConfigurationProviderRule,
             return []
         }
 
-        let parameters = dictionary.enclosedVarParameters
+        let parameters = dictionary.enclosedVarParameters +
+            dictionary.substructure.filter { $0.declarationKind == .varLocal } // capture lists
         let rangeStart = nameOffset + nameLength
         let regex = ClosureParameterPositionRule.openBraceRegex