Imported From: https://issues.scala-lang.org/browse/SI-10120?orig=1
Reporter: @som-snytt
Affected Versions: 2.12.1

@som-snytt said:
There is no -Xprint:scanner. -Ydebug shows:

scala> 'utf-8'
<console>:1: error: unclosed character literal
'utf-8'
      ^
<console>:1: error: [ suppressed ] ';' expected but something found.
'utf-8'
      ^

but could actually show the scansion for the line.

@som-snytt said:
scala/scala#5629

The 'utf-8' message is still the same. Is that intentional?

scala> 'utf_8'
             ^
       error: unclosed character literal (or use " for string literal "utf_8")

scala> 'utf-8'
             ^
       error: unclosed character literal

'utf-8 is scala.Symbol("utf").$minus(8) so it's not as amenable to detecting the pattern.

But it could look for scala.Symbol in the tree and offer the advice. It probably doesn't need to be too precise. Edit: not even that, the error is too low-level. If scanner returned scan errors to the parser, the parser could emit more informed messages.

Or as an approximation, downcast the scanner to grab the source line and check if this isn't the only quote on the line.

scala/scala#6298