SI-7854, SI-6768 better parsing/positioning in parser

The parser hole I found while working on the generated positions
serves as the umbrella for a host of improvements. Upgraded
positions assigned during some specific challenging situations mostly
involving the creation of synthetic trees, e.g. for comprehensions
and closures. While doing so improved some error messages.

Eliminated some of the most glaring duplication in the parser.
It's written like there is some payoff associated with being
spectacularly imperative. Not so far.

1 files changed, 6 insertions, 6 deletions

diff --git a/test/files/neg/t4851.check b/test/files/neg/t4851.check
index 4f2919807e..6d0f424e82 100644
--- a/test/files/neg/t4851.check
+++ b/test/files/neg/t4851.check
@@ -3,19 +3,19 @@ S.scala:2: warning: Adapting argument list by inserting (): leaky (Object-receiv
   given arguments: <none>
  after adaptation: new J((): Unit)
   val x1 = new J
-           ^
+               ^
 S.scala:3: warning: Adapting argument list by inserting (): leaky (Object-receiving) target makes this especially dangerous.
         signature: J(x: Any): J
   given arguments: <none>
  after adaptation: new J((): Unit)
   val x2 = new J()
-           ^
+               ^
 S.scala:4: warning: Adapting argument list by creating a 5-tuple: this may not be what you want.
         signature: J(x: Any): J
   given arguments: 1, 2, 3, 4, 5
  after adaptation: new J((1, 2, 3, 4, 5): (Int, Int, Int, Int, Int))
   val x3 = new J(1, 2, 3, 4, 5)
-           ^
+               ^
 S.scala:6: warning: Adapting argument list by creating a 3-tuple: this may not be what you want.
         signature: Some.apply[A](x: A): Some[A]
   given arguments: 1, 2, 3
@@ -27,19 +27,19 @@ S.scala:7: warning: Adapting argument list by creating a 3-tuple: this may not b
   given arguments: 1, 2, 3
  after adaptation: new Some((1, 2, 3): (Int, Int, Int))
   val y2 = new Some(1, 2, 3)
-           ^
+               ^
 S.scala:9: warning: Adapting argument list by inserting (): this is unlikely to be what you want.
         signature: J2[T](x: T): J2[T]
   given arguments: <none>
  after adaptation: new J2((): Unit)
   val z1 = new J2
-           ^
+               ^
 S.scala:10: warning: Adapting argument list by inserting (): this is unlikely to be what you want.
         signature: J2[T](x: T): J2[T]
   given arguments: <none>
  after adaptation: new J2((): Unit)
   val z2 = new J2()
-           ^
+               ^
 S.scala:14: warning: Adapting argument list by creating a 3-tuple: this may not be what you want.
         signature: Test.anyId(a: Any): Any
   given arguments: 1, 2, 3