Merge pull request swiftlang#190 from google/format-fix-type-decls

Fix type decls containing only a comment.

Author: dabelknap

Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift

@@ -171,12 +171,14 @@ private final class TokenStreamCreator: SyntaxVisitor {
       before(members.leftBrace, tokens: .break)
     }
 
-    if !members.members.isEmpty {
-      after(
-        members.leftBrace,
-        tokens: .close, .close, .break(size: 1, offset: 2), .open(.consistent, 0)
-      )
-      before(members.rightBrace, tokens: .break(size: 1, offset: -2), .close)
+    // The body may be free of other syntax nodes, but we still need to insert the breaks if it
+    // contains a comment (which will be in the leading trivia of the right brace).
+    let commentPrecedesRightBrace = members.rightBrace.leadingTrivia.numberOfComments > 0
+    let isBodyCompletelyEmpty = members.members.isEmpty && !commentPrecedesRightBrace
+
+    if !isBodyCompletelyEmpty {
+      after(members.leftBrace, tokens: .close, .close, .break(offset: 2), .open(.consistent, 0))
+      before(members.rightBrace, tokens: .break(offset: -2), .close)
     } else {
       // The size-0 break in the empty case allows for a break between the braces in the rare event
       // that the declaration would be exactly the column limit + 1.

Tests/SwiftFormatPrettyPrintTests/ClassDeclTests.swift

@@ -291,6 +291,15 @@ public class ClassDeclTests: PrettyPrintTestCase {
     assertPrettyPrintEqual(input: input, expected: wrapped, linelength: 11)
   }
 
+  public func testEmptyClassWithComment() {
+    let input = """
+      class Foo {
+        // foo
+      }
+      """
+    assertPrettyPrintEqual(input: input, expected: input + "\n", linelength: 50)
+  }
+
   public func testOneMemberClass() {
     let input = "class Foo { var bar: Int }"
     assertPrettyPrintEqual(input: input, expected: input + "\n", linelength: 50)

Tests/SwiftFormatPrettyPrintTests/EnumDeclTests.swift

@@ -370,6 +370,15 @@ public class EnumDeclTests: PrettyPrintTestCase {
     assertPrettyPrintEqual(input: input, expected: wrapped, linelength: 10)
   }
 
+  public func testEmptyEnumWithComment() {
+    let input = """
+      enum Foo {
+        // foo
+      }
+      """
+    assertPrettyPrintEqual(input: input, expected: input + "\n", linelength: 50)
+  }
+
   public func testOneMemberEnum() {
     let input = "enum Foo { var bar: Int }"
     assertPrettyPrintEqual(input: input, expected: input + "\n", linelength: 50)

Tests/SwiftFormatPrettyPrintTests/ExtensionDeclTests.swift

@@ -246,6 +246,15 @@ public class ExtensionDeclTests: PrettyPrintTestCase {
     assertPrettyPrintEqual(input: input, expected: wrapped, linelength: 15)
   }
 
+  public func testEmptyExtensionWithComment() {
+    let input = """
+      extension Foo {
+        // foo
+      }
+      """
+    assertPrettyPrintEqual(input: input, expected: input + "\n", linelength: 50)
+  }
+
   public func testOneMemberExtension() {
     let input = "extension Foo { var bar: Int { return 0 } }"
     assertPrettyPrintEqual(input: input, expected: input + "\n", linelength: 50)

Tests/SwiftFormatPrettyPrintTests/ProtocolDeclTests.swift

@@ -239,6 +239,15 @@ public class ProtocolDeclTests: PrettyPrintTestCase {
     assertPrettyPrintEqual(input: input, expected: wrapped, linelength: 14)
   }
 
+  public func testEmptyProtocolWithComment() {
+    let input = """
+      protocol Foo {
+        // foo
+      }
+      """
+    assertPrettyPrintEqual(input: input, expected: input + "\n", linelength: 50)
+  }
+
   public func testOneMemberProtocol() {
     let input = "protocol Foo { var bar: Int { get } }"
     assertPrettyPrintEqual(input: input, expected: input + "\n", linelength: 50)

Tests/SwiftFormatPrettyPrintTests/StructDeclTests.swift

@@ -291,6 +291,15 @@ public class StructDeclTests: PrettyPrintTestCase {
     assertPrettyPrintEqual(input: input, expected: wrapped, linelength: 12)
   }
 
+  public func testEmptyStructWithComment() {
+    let input = """
+      struct Foo {
+        // foo
+      }
+      """
+    assertPrettyPrintEqual(input: input, expected: input + "\n", linelength: 50)
+  }
+
   public func testOneMemberStruct() {
     let input = "struct Foo { var bar: Int }"
     assertPrettyPrintEqual(input: input, expected: input + "\n", linelength: 50)