Check files need to be more versatile for compilation tests with CC Scala 2 library

[Linyxus]

Compiler version

main

Minimized code

The problem is that the error messages in negative tests may look different when compiled with CC Scala 2 library.

Steps for reproduce an example:

sbt> set ThisBuild/Build.scala2Library := Build.Scala2LibraryCCTasty
sbt> scala3-bootstrapped/testCompilation abstract-givens

Output

The test fails with the diff:

index 022c454c31..343ce5ecbd 100644
--- a/tests/neg/abstract-givens.check
+++ b/tests/neg/abstract-givens.check.out
@@ -1,7 +1,7 @@
 -- Error: tests/neg/abstract-givens.scala:11:8 -------------------------------------------------------------------------
 11 |  given s[T](using T): Seq[T] with // error
    |        ^
-   |instance cannot be created, since def iterator: Iterator[A] in trait IterableOnce in package scala.collection is not defined 
+   |instance cannot be created, since def iterator: Iterator[A]^{this} in trait IterableOnce in package scala.collection is not defined 
 -- [E164] Declaration Error: tests/neg/abstract-givens.scala:8:8 -------------------------------------------------------
 8 |  given y(using Int): String = summon[Int].toString * 22 // error
   |   

[odersky]

Which other files are failing with check errors?

Maybe we can tweak the error message rendering so that capture sets are printed only if the current compilation unit is itself capture checked?