Directly generate func ==(lhs:, rhs:) -> Bool.

Maintain the older _protobuf_ method to not break source compatibility, but
remove the indirection.

Author: thomasvl

Sources/SwiftProtobuf/Message.swift

@@ -174,6 +174,8 @@ public extension Message {
 /// multiple message types that uses equality tests, puts messages in a `Set`,
 /// or uses them as `Dictionary` keys.
 public protocol _MessageImplementationBase: Message, Hashable {
+
+  // Legacy function; no longer used, but left to maintain source compatibility.
   func _protobuf_generated_isEqualTo(other: Self) -> Bool
 }
 
@@ -185,7 +187,16 @@ public extension _MessageImplementationBase {
     return self == other
   }
 
+  // Legacy default implementation that is used by old generated code, current
+  // versions of the plugin/generator provide this directly, but this is here
+  // just to avoid breaking source compatibility.
   public static func ==(lhs: Self, rhs: Self) -> Bool {
     return lhs._protobuf_generated_isEqualTo(other: rhs)
   }
+
+  // Legacy function that is generated by old versions of the plugin/generator,
+  // defaulted to keep things simple without changing the api surface.
+  public func _protobuf_generated_isEqualTo(other: Self) -> Bool {
+    return self == other
+  }
 }

Sources/protoc-gen-swift/MessageFieldGenerator.swift

@@ -138,14 +138,17 @@ class MessageFieldGenerator: FieldGeneratorBase, FieldGenerator {
     }
 
     func generateFieldComparison(printer p: inout CodePrinter) {
+        let lhsProperty: String
         let otherStoredProperty: String
         if usesHeapStorage {
-            otherStoredProperty = "other_storage.\(underscoreSwiftName)"
+            lhsProperty = "_storage.\(underscoreSwiftName)"
+            otherStoredProperty = "rhs_storage.\(underscoreSwiftName)"
         } else {
-            otherStoredProperty = "other.\(hasFieldPresence ? underscoreSwiftName : swiftName)"
+            lhsProperty = "lhs.\(hasFieldPresence ? underscoreSwiftName : swiftName)"
+            otherStoredProperty = "rhs.\(hasFieldPresence ? underscoreSwiftName : swiftName)"
         }
 
-        p.print("if \(storedProperty) != \(otherStoredProperty) {return false}\n")
+        p.print("if \(lhsProperty) != \(otherStoredProperty) {return false}\n")
     }
 
    func generateRequiredFieldCheck(printer p: inout CodePrinter) {

Sources/protoc-gen-swift/MessageGenerator.swift

@@ -221,7 +221,7 @@ class MessageGenerator {
     p.print("\n")
     generateTraverse(printer: &p)
     p.print("\n")
-    generateMessageImplementationBase(printer: &p)
+    generateMessageEquality(printer: &p)
     p.outdent()
     p.print("}\n")
 
@@ -345,22 +345,23 @@ class MessageGenerator {
     p.print("}\n")
   }
 
-  private func generateMessageImplementationBase(printer p: inout CodePrinter) {
-    p.print("\(visibility)func _protobuf_generated_isEqualTo(other: \(swiftFullName)) -> Bool {\n")
+  private func generateMessageEquality(printer p: inout CodePrinter) {
+    p.print("\(visibility)static func ==(lhs: \(swiftFullName), rhs: \(swiftFullName)) -> Bool {\n")
     p.indent()
     var compareFields = true
     if let storage = storage {
-      p.print("if _storage !== other._storage {\n")
+      p.print("if lhs._storage !== rhs._storage {\n")
       p.indent()
       p.print("let storagesAreEqual: Bool = ")
       if storage.storageProvidesEqualTo {
-        p.print("_storage.isEqualTo(other: other._storage)\n")
+        p.print("lhs._storage.isEqualTo(other: rhs._storage)\n")
         compareFields = false
       }
     }
     if compareFields {
       generateWithLifetimeExtension(printer: &p,
-                                    alsoCapturing: "other") { p in
+                                    alsoCapturing: "rhs",
+                                    selfQualifier: "lhs") { p in
         for f in fields {
           f.generateFieldComparison(printer: &p)
         }
@@ -374,9 +375,9 @@ class MessageGenerator {
       p.outdent()
       p.print("}\n")
     }
-    p.print("if unknownFields != other.unknownFields {return false}\n")
+    p.print("if lhs.unknownFields != rhs.unknownFields {return false}\n")
     if isExtensible {
-      p.print("if _protobuf_extensionFieldValues != other._protobuf_extensionFieldValues {return false}\n")
+      p.print("if lhs._protobuf_extensionFieldValues != rhs._protobuf_extensionFieldValues {return false}\n")
     }
     p.print("return true\n")
     p.outdent()
@@ -457,25 +458,33 @@ class MessageGenerator {
     throws canThrow: Bool = false,
     returns: Bool = false,
     alsoCapturing capturedVariable: String? = nil,
+    selfQualifier qualifier: String? = nil,
     body: (inout CodePrinter) -> Void
   ) {
     if storage != nil {
       let prefixKeywords = "\(returns ? "return " : "")" +
         "\(canThrow ? "try " : "")"
       p.print(prefixKeywords)
 
+      let selfQualifier: String
+      if let qualifier = qualifier {
+        selfQualifier = "\(qualifier)."
+      } else {
+        selfQualifier = ""
+      }
+
       if let capturedVariable = capturedVariable {
         // withExtendedLifetime can only pass a single argument,
         // so we have to build and deconstruct a tuple in this case:
-        let actualArgs = "(_storage, \(capturedVariable)._storage)"
+        let actualArgs = "(\(selfQualifier)_storage, \(capturedVariable)._storage)"
         let formalArgs = "(_args: (_StorageClass, _StorageClass))"
         p.print("withExtendedLifetime(\(actualArgs)) { \(formalArgs) in\n")
         p.indent()
         p.print("let _storage = _args.0\n")
         p.print("let \(capturedVariable)_storage = _args.1\n")
       } else {
         // Single argument can be passed directly:
-        p.print("withExtendedLifetime(_storage) { (_storage: _StorageClass) in\n")
+        p.print("withExtendedLifetime(\(selfQualifier)_storage) { (_storage: _StorageClass) in\n")
         p.indent()
       }
     }

Sources/protoc-gen-swift/OneofGenerator.swift

@@ -368,9 +368,9 @@ class OneofGenerator {
 
         let otherStoredProperty: String
         if usesHeapStorage {
-          otherStoredProperty = "other_storage.\(underscoreSwiftFieldName)"
+          otherStoredProperty = "rhs_storage.\(underscoreSwiftFieldName)"
         } else {
-          otherStoredProperty = "other.\(swiftFieldName)"
+          otherStoredProperty = "rhs.\(swiftFieldName)"
         }
 
         p.print("if \(storedProperty) != \(otherStoredProperty) {return false}\n")