Merge pull request swiftlang#226 from dabelknap/whitespace-linter

Use the pretty-printer output for whitespace linting

Author: dabelknap

Package.swift

@@ -44,6 +44,7 @@ let package = Package(
         "SwiftFormatCore",
         "SwiftFormatPrettyPrint",
         "SwiftFormatRules",
+        "SwiftFormatWhitespaceLinter",
         "SwiftSyntax",
       ]
     ),
@@ -57,6 +58,13 @@ let package = Package(
       name: "SwiftFormatPrettyPrint",
       dependencies: ["SwiftFormatCore", "SwiftFormatConfiguration"]
     ),
+    .target(
+      name: "SwiftFormatWhitespaceLinter",
+      dependencies: [
+        "SwiftFormatCore",
+        "SwiftSyntax",
+      ]
+    ),
     .target(name: "generate-pipeline", dependencies: ["SwiftSyntax"]),
     .target(
       name: "swift-format",
@@ -89,5 +97,14 @@ let package = Package(
         "SwiftSyntax",
       ]
     ),
+    .testTarget(
+      name: "SwiftFormatWhitespaceLinterTests",
+      dependencies: [
+        "SwiftFormatConfiguration",
+        "SwiftFormatCore",
+        "SwiftFormatWhitespaceLinter",
+        "SwiftSyntax",
+      ]
+    ),
   ]
 )

Sources/SwiftFormat/SwiftLinter.swift

@@ -13,6 +13,8 @@
 import Foundation
 import SwiftFormatConfiguration
 import SwiftFormatCore
+import SwiftFormatPrettyPrint
+import SwiftFormatWhitespaceLinter
 import SwiftSyntax
 
 /// Diagnoses and reports problems in Swift source code or syntax trees according to the Swift style
@@ -64,7 +66,15 @@ public final class SwiftLinter {
 
     pipeline.visit(syntax as Syntax)
 
-    // TODO: Extend the pretty printer to make it possible to lint spacing and breaking issues.
+    // Perform whitespace linting by comparing the input source text with the output of the
+    // pretty-printer.
+    let printer = PrettyPrinter(
+      context: context,
+      node: syntax,
+      printTokenStream: debugOptions.contains(.dumpTokenStream))
+    let formatted = printer.prettyPrint()
+    let ws = WhitespaceLinter(user: syntax.description, formatted: formatted, context: context)
+    ws.lint()
   }
 
   // TODO: Add an overload of `lint` that takes the source text directly.