Cyclic error for `import scala.runtime.stdLibPatches.Predef.assert`

[WojciechMazur]

Based on OpenCB failure for beangle/commons - Open CB logs

Compiler version

Last good release: 3.8.0-RC1-bin-20250816-644bd7f-NIGHTLY
First bad release: 3.8.0-RC1-bin-20250816-fdf052d-NIGHTLY
Bisect points to aae5acb

Minimized code

import scala.runtime.stdLibPatches.Predef.assert

Output

> scala compile example.scala -S 3.8.0-RC1-bin-20250822-658c8bd-NIGHTLY -explain-cyclic
Compiling project (Scala 3.8.0-RC1-bin-20250822-658c8bd-NIGHTLY, JVM (21))
[error] ./example.scala:1:8
[error] Cyclic reference involving method assert
[error] 
[error] The error occurred while trying to compute the signature of method assert
[error]   which required to read the definition of method assert in /Users/wmazur/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala3-library_3/3.8.0-RC1-bin-20250822-658c8bd-NIGHTLY/scala3-library_3-3.8.0-RC1-bin-20250822-658c8bd-NIGHTLY.jar(scala/runtime/stdLibPatches/Predef.tasty)
[error]   which required to compute the base classes of class SourceFile
[error]   which required to compute the signature of class SourceFile
[error]   which required to read the definition of class SourceFile in /Users/wmazur/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala3-library_3/3.8.0-RC1-bin-20250822-658c8bd-NIGHTLY/scala3-library_3-3.8.0-RC1-bin-20250822-658c8bd-NIGHTLY.jar(scala/annotation/internal/SourceFile.tasty)
[error]   which required to compute the signature of object Predef
[error]   which required to compute the signature of object Predef
[error]   which required to compute the signature of method assert
[error] 
[error]  Run with both -explain-cyclic and -Ydebug-cyclic to see full stack trace.
[error] import scala.runtime.stdLibPatches.Predef.assert
[error]        ^
Error compiling project (Scala 3.8.0-RC1-bin-20250822-658c8bd-NIGHTLY, JVM (21))

Expectation

Probably won't fix, but all definitions present in stdlibPatches should be deprecated in 3.8 and removed in 3.9

[hamzaremmal]

@WojciechMazur All the definitions will be made private[scala] once we kill definitely the old build.
It's in the roadmap, we just haven't reached it yet.

Also, no one should actually put in source import scala.runtime.stdLibPatches.Predef.assert, it should be import scala.Predef.assert (which is already by default imported).

[WojciechMazur]

I assumed that might be the case, but still there is at least 1 usage of it https://github.com/beangle/commons/blob/087b4ee3895e3584b0c7297031d8e8b49d5e109f/src/test/scala/org/beangle/commons/NumbersTest.scala#L25

I wonder should we deprecate it (and can we, since I don't how it is actually being used) in 3.7.3-RC3 just for sanity, since we're going to make it unavailable completely in 3.8.0. Everything inside scala.runtime should be treated as Scala langauge private by users, but we cannot really force it.

[hamzaremmal]

I don't think we should do anything for the migration. This is a case of removing an import that should have never been there in the first place. I opened a PR for this in the upstream repository.
If an other project ever referred to this object, they should just remove the reference to it. It's a simple migration path, I don't think we should spend time on it.

[sjrd]

scala.runtime is off limits to users. If they refer to it, it's on them.

[hamzaremmal]

I agree with @sjrd.

[He-Pin]

Maybe we can add some annotation like Akka, eg InternalApi to scala.runtime?

[Gedochao]

scala.runtime is off limits to users. If they refer to it, it's on them.

If this is the case, then we need a warning when it is used.

Maybe we can add some annotation like Akka, eg InternalApi to scala.runtime?

+1
cc @sjrd @hamzaremmal

[Gedochao]

So... I'm getting the vibe that this is a won't fix, but we should still let users know that scala.runtime shouldn't be used with a warning.
I think that should be a separate ticket, however.
I'll close this when that ticket gets defined.