Cleanup Tailrec

Author: allanrenucci

compiler/src/dotty/tools/dotc/config/Printers.scala

@@ -32,6 +32,7 @@ object Printers {
   val plugins: Printer = noPrinter
   val simplify: Printer = noPrinter
   val subtyping: Printer = noPrinter
+  val tailrec: Printer = noPrinter
   val transforms: Printer = noPrinter
   val typr: Printer = noPrinter
   val unapp: Printer = noPrinter

compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala

@@ -1801,12 +1801,11 @@ object messages {
   case class TailrecNotApplicable(symbol: Symbol)(implicit ctx: Context)
     extends Message(TailrecNotApplicableID) {
     val kind: String = "Syntax"
-    val symbolKind: String = symbol.showKind
     val msg: String =
       if (symbol.is(Method))
-        hl"TailRec optimisation not applicable, $symbol is neither ${"private"} nor ${"final"}."
+        "TailRec optimisation not applicable, method not tail recursive"
       else
-        hl"TailRec optimisation not applicable, ${symbolKind} isn't a method."
+        hl"TailRec optimisation not applicable, ${symbol.showKind} isn't a method."
     val explanation: String =
       hl"A method annotated ${"@tailrec"} must be declared ${"private"} or ${"final"} so it can't be overridden."
   }

compiler/src/dotty/tools/dotc/transform/TailRec.scala

@@ -1507,8 +1507,8 @@ class ErrorMessagesTests extends ErrorMessagesTest {
       implicit val ctx: Context = ictx
       assertMessageCount(4, messages)
 
-      val tailRegMessages = messages.map({ case m: TailrecNotApplicable => m.symbolKind }).toSet
-      assertEquals(tailRegMessages, Set("variable", "value", "object", "class"))
+      val tailRecMessages = messages.map({ case TailrecNotApplicable(sym) => sym.showKind }).toSet
+      assertEquals(tailRecMessages, Set("variable", "value", "object", "class"))
     }
 
   @Test def notAnExtractor() =

compiler/test/dotty/tools/dotc/reporting/ErrorMessagesTests.scala

@@ -1,5 +1,7 @@
+import annotation.tailrec
+
 object Test1772B {
-  @annotation.tailrec
+  @tailrec
   def bar : Nothing = { // error: TailRec optimisation not applicable
     try {
       throw new RuntimeException
@@ -10,7 +12,7 @@ object Test1772B {
     }
   }
 
-  @annotation.tailrec
+  @tailrec
   def baz : Nothing = { // error: TailRec optimisation not applicable
     try {
       throw new RuntimeException
@@ -21,7 +23,7 @@ object Test1772B {
     }
   }
 
-  @annotation.tailrec
+  @tailrec
   def boz : Nothing = { // error: TailRec optimisation not applicable
     try {
       throw new RuntimeException
@@ -30,7 +32,7 @@ object Test1772B {
     }
   }
 
-  @annotation.tailrec
+  @tailrec
   def bez : Nothing = { // error: TailRec optimisation not applicable
     try {
       bez // error: it is not in tail position
@@ -40,7 +42,7 @@ object Test1772B {
   }
 
   // the `liftedTree` local method will prevent a tail call here.
-  @annotation.tailrec
+  @tailrec
   def bar(i : Int) : Int = { // error: TailRec optimisation not applicable
     if (i == 0) 0
     else 1 + (try {

tests/neg-tailcall/t1672b.check

@@ -1,3 +1,3 @@
 object Test {
-  @annotation.tailrec def foo() = 5                   // error
+  @annotation.tailrec def foo() = 5 // error: not recursive
 }

tests/neg-tailcall/t1672b.scala

@@ -1,10 +1,12 @@
+import annotation.tailrec
+
 class Bad[X, Y](val v: Int) extends AnyVal {
-  @annotation.tailrec final def notTailPos[Z](a: Int)(b: String): Unit = {   // error
-    this.notTailPos[Z](a)(b)          // error
+  @tailrec final def notTailPos[Z](a: Int)(b: String): Unit = { // error: TailRec optimisation not applicable
+    this.notTailPos[Z](a)(b) // error: it is not in tail position
     println("tail")
   }
 
-  @annotation.tailrec final def differentTypeArgs: Unit = {
+  @tailrec final def differentTypeArgs: Unit = {
     {(); new Bad[String, Unit](0)}.differentTypeArgs
   }
 }