Update generation to use normalized extension ranges.

Fixes some extension out of order cases, but also collapses the ranges
to make slightly better code.

Author: thomasvl

Sources/protoc-gen-swift/Descriptor+Extensions.swift

@@ -79,7 +79,7 @@ extension Descriptor {
   /// This expression list is suitable as a pattern match in a `case`
   /// statement. For example, `"case 5..<10, 20..<30:"`.
   var swiftExtensionRangeExpressions: String {
-    return extensionRanges.lazy.map {
+    return normalizedExtensionRanges.lazy.map {
       $0.swiftRangeExpression
     }.joined(separator: ", ")
   }
@@ -90,7 +90,7 @@ extension Descriptor {
   /// - Parameter variable: The name of the variable to test in the expression.
   /// - Returns: A `String` containing the Boolean expression.
   func swiftExtensionRangeBooleanExpression(variable: String) -> String {
-    return extensionRanges.lazy.map {
+    return normalizedExtensionRanges.lazy.map {
       "(\($0.swiftBooleanExpression(variable: variable)))"
     }.joined(separator: " || ")
   }

Sources/protoc-gen-swift/MessageGenerator.swift

@@ -331,7 +331,7 @@ class MessageGenerator {
       let visitExtensionsName =
         descriptor.useMessageSetWireFormat ? "visitExtensionFieldsAsMessageSet" : "visitExtensionFields"
 
-      var ranges = descriptor.extensionRanges.makeIterator()
+      var ranges = descriptor.normalizedExtensionRanges.makeIterator()
       var nextRange = ranges.next()
       for f in fieldsSortedByNumber {
         while nextRange != nil && Int(nextRange!.start) < f.number {

Sources/protoc-gen-swift/OneofGenerator.swift

@@ -150,7 +150,7 @@ class OneofGenerator {
         // from each extension range as an easy way to check for them being
         // mixed in between the fields.
         var parentNumbers = descriptor.containingType.fields.map { Int($0.number) }
-        parentNumbers.append(contentsOf: descriptor.containingType.extensionRanges.map { Int($0.start) })
+        parentNumbers.append(contentsOf: descriptor.containingType.normalizedExtensionRanges.map { Int($0.start) })
         var parentNumbersIterator = parentNumbers.sorted(by: { $0 < $1 }).makeIterator()
         var nextParentFieldNumber = parentNumbersIterator.next()
         var grouped = [[MemberFieldGenerator]]()