Suggested import is not always helpful when suggestion is too generic

[eejbyfeldt]

Compiler version

3.7.4, 3.8.0-RC1-bin-20251113-8b5d445-NIGHTLY

Minimized example

$ cat suggested_import.scala 
import scala.deriving.Mirror

object test {
  object Generic:
    given fromMirror[M <: Mirror](using m: M): M = ???
  trait TC[A]

  summon[TC[Int]]
}

Output Error/Warning message

$ scala-cli -S 3.nightly suggested_import.scala 
Compiling project (Scala 3.8.0-RC1-bin-20251113-8b5d445-NIGHTLY, JVM (21))
[error] ./suggested_import.scala:8:18
[error] No given instance of type test.TC[Int] was found for parameter x of method summon in object Predef
[error] 
[error] The following import might make progress towards fixing the problem:
[error] 
[error]   import test.Generic.fromMirror
[error] 
[error]   summon[TC[Int]]
[error]                  ^

Why this Error/Warning was not helpful

The message was unhelpful because importing fromMirror will not help.

Suggested improvement

It could be made more helpful by not suggesting anything. In the provided code there is not import that will help.

[eejbyfeldt]

This was minimized based on code using https://github.com/typelevel/shapeless-3

$ cat suggested_import_shapeless.scala 
//> using dep "org.typelevel::shapeless3-deriving:3.5.0"
import shapeless3.deriving.K0

object test {
  trait TC[A]
  given seq[T: TC]: TC[Seq[T]] = ???

  summon[TC[Seq[Int]]]
}
$ scala-cli -S 3.nightly suggested_import_shapeless.scala 
Compiling project (Scala 3.8.0-RC1-bin-20251113-8b5d445-NIGHTLY, JVM (21))
[error] ./suggested_import_shapeless.scala:8:23
[error] No given instance of type test.TC[Seq[Int]] was found for parameter x of method summon in object Predef.
[error] I found:
[error] 
[error]     test.seq[Int](/* missing */summon[test.TC[Int]])
[error] 
[error] But no implicit values were found that match type test.TC[Int].
[error] 
[error] One of the following imports might make progress towards fixing the problem:
[error] 
[error]   import shapeless3.deriving.K0.Generic.fromMirror
[error]   import shapeless3.deriving.K1.Generic.fromMirror
[error]   import shapeless3.deriving.K11.Generic.fromMirror
[error]   import shapeless3.deriving.K2.Generic.fromMirror
[error] 
[error]   summon[TC[Seq[Int]]]
[error]                       ^
Error compiling project (Scala 3.8.0-RC1-bin-20251113-8b5d445-NIGHTLY, JVM (21))
Compilation failed

This errors are particularly unhelpful for "indirect" users of shapeless as it might be hard for them to know that the suggestions are unhelpful.