Merge pull request #942 from TTOzzi/configuration_decoding_error

Make the error message for an invalid version more user-friendly

Author: allevato

Sources/SwiftFormat/API/Configuration.swift

@@ -285,11 +285,9 @@ public struct Configuration: Codable, Equatable {
     // If the version number is not present, assume it is 1.
     self.version = try container.decodeIfPresent(Int.self, forKey: .version) ?? 1
     guard version <= highestSupportedConfigurationVersion else {
-      throw DecodingError.dataCorruptedError(
-        forKey: .version,
-        in: container,
-        debugDescription:
-          "This version of the formatter does not support configuration version \(version)."
+      throw SwiftFormatError.unsupportedConfigurationVersion(
+        version,
+        highestSupported: highestSupportedConfigurationVersion
       )
     }
 

Sources/SwiftFormat/API/SwiftFormatError.swift

@@ -31,6 +31,9 @@ public enum SwiftFormatError: LocalizedError {
   /// An error happened while dumping the tool's configuration.
   case configurationDumpFailed(String)
 
+  /// The provided configuration version is not supported by this version of the formatter.
+  case unsupportedConfigurationVersion(Int, highestSupported: Int)
+
   public var errorDescription: String? {
     switch self {
     case .fileNotReadable:
@@ -43,6 +46,9 @@ public enum SwiftFormatError: LocalizedError {
       return "experimental feature '\(name)' was not recognized by the Swift parser"
     case .configurationDumpFailed(let message):
       return "dumping configuration failed: \(message)"
+    case .unsupportedConfigurationVersion(let version, let highestSupported):
+      return
+        "This version of the formatter does not support configuration version \(version). The highest supported version is \(highestSupported)."
     }
   }
 }

Sources/swift-format/Frontend/Frontend.swift

@@ -99,7 +99,7 @@ class Frontend {
           // Fall through to the default return at the end of the function.
         } catch {
           diagnosticsEngine.emitError(
-            "Unable to read configuration for \(swiftFileURL.path): \(error.localizedDescription)"
+            "Unable to read configuration for \(swiftFileURL.relativePath): \(error.localizedDescription)"
           )
           return nil
         }
@@ -116,7 +116,7 @@ class Frontend {
           }
         } catch {
           diagnosticsEngine.emitError(
-            "Unable to read configuration for \(cwd): \(error.localizedDescription)"
+            "Unable to read configuration for \(cwd.relativePath): \(error.localizedDescription)"
           )
           return nil
         }

api-breakages.txt

@@ -3,3 +3,4 @@
 
 API breakage: constructor FileIterator.init(urls:followSymlinks:) has been removed
 API breakage: enumelement SwiftFormatError.configurationDumpFailed has been added as a new enum case
+API breakage: enumelement SwiftFormatError.unsupportedConfigurationVersion has been added as a new enum case