Pretty-print method types with a ": " before a non-method return type

Author: smarter

compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala

@@ -169,7 +169,8 @@ class PlainPrinter(_ctx: Context) extends Printer {
         changePrec(GlobalPrec) {
           (if (tp.isImplicit) "(implicit " else "(") ~
             Text((tp.paramNames, tp.paramInfos).zipped map paramText, ", ") ~
-          ")" ~ toText(tp.resultType)
+          (if (tp.resultType.isInstanceOf[MethodType]) ")" else "): ") ~
+          toText(tp.resultType)
         }
       case tp: ExprType =>
         changePrec(GlobalPrec) { "=> " ~ toText(tp.resultType) }

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

@@ -384,7 +384,7 @@ class ErrorMessagesTests extends ErrorMessagesTest {
       val MethodDoesNotTakeParameters(tree, methodPart) :: Nil = messages
 
       assertEquals("Scope.foo(1)", tree.show)
-      assertEquals("((a: Int)Unit)(Scope.foo)", methodPart.show)
+      assertEquals("((a: Int): Unit)(Scope.foo)", methodPart.show)
     }
 
   @Test def ambiugousOverloadWithWildcard =
@@ -408,7 +408,7 @@ class ErrorMessagesTests extends ErrorMessagesTest {
       assertMessageCount(1, messages)
       val AmbiguousOverload(tree, List(alt1, alt2), pt: WildcardType) :: Nil = messages
       assertEquals("method foo", alt1.show)
-      assertEquals("(s: String)String", alt1.info.show)
+      assertEquals("(s: String): String", alt1.info.show)
       assertEquals("method foo", alt2.show)
     }