Better positions for infix term operations.

Preserving the position of infix operators is useful for IDEs'
type-at-point. We also preserve the position of the untyped lhs of
right-associative operators, this is useful both for IDEs and for error
messages, before:
4 |val x: List[Int] = "foo" :: List(1)
  |                                   ^
  |                                   found:    String($1$)
  |                                   required: Int
  |

After:
scala> val x: List[Int] = "foo" :: List(1)
-- [E007] Type Mismatch Error: <console> ---------------------------------------
4 |val x: List[Int] = "foo" :: List(1)
  |                   ^^^^^
  |                   found:    String($1$)
  |                   required: Int
  |

Note: It would be even nicer if we displayed "String" instead of
"String($1$)" since $1$ is synthetic, this commit does not address this.

1 files changed, 7 insertions, 0 deletions

diff --git a/tests/repl/errmsgs.check b/tests/repl/errmsgs.check
index f0ccdf53f..0dc8e8ae5 100644
--- a/tests/repl/errmsgs.check
+++ b/tests/repl/errmsgs.check
@@ -78,4 +78,11 @@ scala> class Foo() { def bar: Int = 1 }; val foo = new Foo(); foo.barr
 4 |class Foo() { def bar: Int = 1 }; val foo = new Foo(); foo.barr
   |                                                       ^^^^^^^^
   |        value `barr` is not a member of Foo(foo) - did you mean `foo.bar`?
+scala> val x: List[Int] = "foo" :: List(1)
+-- [E007] Type Mismatch Error: <console> ---------------------------------------
+4 |val x: List[Int] = "foo" :: List(1)
+  |                   ^^^^^
+  |                   found:    String($1$)
+  |                   required: Int
+  |                   
 scala> :quit