Infinite compile time when exceeded amount of parameters of class

[Nojipiz]

Compiler version

Scala: 3.3.3

Minimized code

  trait ExampleTrait1
  trait ExampleTrait2
  class ExampleClass(traitOne: ExampleTrait1, traitTwo: ExampleTrait2)

  def fun[In](a: In): Unit = println(0)

  fun(new ExampleClass(_, _, _))

Output

java.lang.OutOfMemoryError: Java heap space

Expectation

An error at compile time because the exceeded parameter of "ExampleClass", it just tries to compile until the java heap space is over.

[Gedochao]

Fails at compile time in Next (3.4.1)

-- [E081] Type Error: /Users/pchabelski/IdeaProjects/scala-cli-tests/compiler-repro/.scala-build/compiler-repro_b7340921ea-40b92162c2/src_generated/main/smth.scala:13:27 
13 |fun(new ExampleClass(_, _, _))
   |                           ^
   |        Missing parameter type
   |
   |        I could not infer the type of the parameter _$3
   |        in expanded function:
   |          (_$1, _$2, _$3) => new smth$_.this.ExampleClass(_$1, _$2, _$3)
   |        Expected type for the whole anonymous function:
   |          In
   |
   |        where:    In is a type variable
1 error found
Compilation failed

The compilation indeed hangs in LTS.

[Gedochao]

So this unfortunately looks like a regression on the LTS.

The last LTS to fail correctly in compile time: 3.3.1

-- [E081] Type Error: /Users/pchabelski/IdeaProjects/scala-cli-tests/compiler-repro/.scala-build/compiler-repro_a69ec373e9-40b92162c2/src_generated/main/smth.scala:13:27 
13 |fun(new ExampleClass(_, _, _))
   |                           ^
   |   Missing parameter type
   |
   |   I could not infer the type of the parameter _$3 of expanded function:
   |   (_$1, _$2, _$3) => new smth$_.this.ExampleClass(_$1, _$2, _$3).
1 error found
Compilation failed

The first LTS to hang on infinite compilation: 3.3.2
Last good nightly (raising the error): 3.3.2-RC1-bin-20230717-2753a17-NIGHTLY
First nightly introducing the problem: 3.3.2-RC1-bin-20230718-da16f43-NIGHTLY

The compilation still hangs on Next 3.4.0
First Next nightly to fix it (have the error again, rather than hang): 3.4.1-RC1-bin-20240122-ca18f4a-NIGHTLY
First good Next is 3.4.1

[noti0na1]

I couldn't reproduce the infinite hang in LTS (3.3.3), 3.4, or nightly

> scala-cli compile -S 3.lts Stest.scala
Compiling project (Scala 3.3.3, JVM (11))
[error] ./Stest.scala:234:26
[error] Could not infer type for parameter _$3 of anonymous function
[error] 
[error] In expanded function:
[error] (_$1, _$2, _$3) => new ExampleClass(_$1, _$2, _$3)
[error]   new ExampleClass(_, _, _)
[error]                          ^
Error compiling project (Scala 3.3.3, JVM (11))
Compilation failed

Although the error is different in 3.3.

[Nojipiz]

@noti0na1 How did you use "3.lts" as Scala Version for scala-cli?

When i try to execute your command the output is:

[error]  Cannot find matching Scala version for '3.lts
You can only choose one of the 3.x, 2.13.x, and 2.12.x. versions.
The latest supported stable versions are 2.12.17, 2.13.10, 3.2.2.
In addition, you can request compilation with the last nightly versions of Scala,
by passing the 2.nightly, 2.12.nightly, 2.13.nightly, or 3.nightly arguments.
Specific Scala 2 or Scala 3 nightly versions are also accepted.

Even with scala-cli, you can reproduce the error using

• Scala-CLI version 1.0.0-RC2
• OpenJDK 19
• Scala 3.3.3

> scala-cli compile -S 3.3.3 Stest.scala
Starting compilation server
Compiling project (Scala 3.3.3, JVM)

And it hangs until java.lang.OutOfMemoryError: Java heap space

[He-Pin]

You need scala cli 1.3.1

[Nojipiz]

Thanks @He-Pin, the latest Scala-cli version that i got from my distro is 1.3.0 but it was enough to run the command.

scala-cli updated and it stills goes to "infinite compiling"

• Scala-CLI version 1.0.0-RC2
• OpenJDK 21
• Scala 3.3.3 (using the 3.lts version at scala-cli)

> scala-cli compile -S 3.lts Stest.scala
Starting compilation server
Compiling project (Scala 3.3.3, JVM (21))

And it does nothing from there.

[noti0na1]

I was able to reproduce on my another system, with smaller memory.

[noti0na1]

The nightly versions I found may related to this issue:

• 3.4.0-RC1-bin-20240105-d2cc3ae-NIGHTLY
• 3.4.0-RC1-bin-20240106-c15cc9c-NIGHTLY

[WojciechMazur]

The bisect for a fix seems to point to 708e640, cherry-pick to the current LTS seems to fix the issue