Extremely slow compilation when silencer plugin enabled

[payurgin]

Next lines of code compiles at least 25 seconds when silencer plugin enabled and just 1 seconds with disabled plugin

import sttp.tapir._

case class Foo(a: Int)

object Main extends App {
  val a = implicitly[Schema[Foo]]
    .modify(_.a)(_.description("foo")) // 1s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 1s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 1s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 1s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 1s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 1s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 1s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 1s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 1s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 1s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 2s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 6s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 16s with silencer and 1s without
    .modify(_.a)(_.description("foo")) // 25s with silencer and 1s without
}

where modify - is macro function from tapir library.

Repo with simple reproducer: https://github.com/igrocki/slow-silencer-tapir

I found ugly workaround: breaking method chain into two or more chains like:

val a = implicitly[Schema[Foo]]
    .modify(_.a)(_.description("foo")) 
    .modify(_.a)(_.description("foo")) 
    .modify(_.a)(_.description("foo")) 
    .modify(_.a)(_.description("foo")) 
    .modify(_.a)(_.description("foo")) 
    .modify(_.a)(_.description("foo")) 

val b = a.modify(_.a)(_.description("foo"))
    .modify(_.a)(_.description("foo")) 
    .modify(_.a)(_.description("foo")) 
    .modify(_.a)(_.description("foo")) 
    .modify(_.a)(_.description("foo")) 
    .modify(_.a)(_.description("foo")) 
    .modify(_.a)(_.description("foo")) 
    .modify(_.a)(_.description("foo")) 

[SethTisue]

very nice catch!! 👏 thank you for isolating and reporting

[SethTisue]

fwiw, scala/scala#8373 doesn't seem to have this problem (tested with 2.13.2-bin-59cf05f-SNAPSHOT). I wonder what @lrytz did differently. (of course, it's easier to avoid extra traversals and such when something is integrated into the compiler directly, so perhaps there's no mystery.)

[ghik]

This is caused by tapir's macros which seem to blow up exponentially. Silencer looks for @silent annotations in both macro expandees and macro expansions. In the reproduction provided by @igrocki (huge thanks!) silencer has to traverse 1659690482(!) trees. But when I disabled looking for @silent annotation in macro expansions, it drastically went down to just 569 trees and compilation time dropped accordingly.

I probably could just ignore macro expansions as it's very unlikely that someone would put @silent annotations in macro generated code, but I'm not sure if it won't break something.

[ghik]

Ok, I've decided to go on and ignore macro expansions by default. I've also introduced an option to bring back the old behaviour (-P:silencer:searchMacroExpansions).
These changes are available in freshly released 1.6.0

[SethTisue]

This is caused by tapir's macros which seem to blow up exponentially

I wonder if tapir's maintainers know about that.

[adamw]

@SethTisue yes :) softwaremill/tapir#455