Inductive-implicit-benchmark fails locally before bootstrap but not on CI

[Blaisorblade]

Since a while, testCompilation fails on inductive-implicits-bench.scala with a stack overflow before bootstrap, but not after bootstrap or on CI. This passes after bootstrap, I think, because of methods that are only tail-recursive if track is inlined. And it passes with -Xss2m in agentOptions (apparently neither sbt's JVM options nor ones in RunnerOrchestration are involved).

Still, why does this pass in the CI? @nicolasstucki wonders if it's due to Linux on the CI (I and @nicolasstucki are on Mac and both see the issue), I wonder if it's due to a different JVM version (FWIW I'm on 1.8.0_172-b11).

[info] Test dotty.tools.dotc.CompilationTests.pos started
-- Error: /Users/pgiarrusso/git/dotty-master-nonwt/tests/pos-deep-subtype/inductive-implicits-bench.scala:60:20 --------
60 |  val sel = Selector[L, Boolean]
   |                    ^
   |Recursion limit exceeded.
   |Maybe there is an illegal cyclic reference?
   |If that's not the case, you could also try to increase the stacksize using the -Xss JVM option.
   |A recurring operation is (inner to outer):
   |
   |  subtype H <:< Int
   |  subtype H :: T <:< Int :: Int :: Int :: Int :: Int :: Int :: Int :: Boolean :: shapeless.HNil
   |  subtype shapeless.Selector[H :: T, H] <:< shapeless.Selector[Int :: Int :: Int :: Int :: Int :: Int :: Int :: Boolean :: shapeless.HNil, Boolean]
[=======================================] completed (1/1, 1 failed, 3s)
[error] Test dotty.tools.dotc.CompilationTests.pos failed: java.lang.AssertionError: Expected no errors when compiling, failed for the following reason(s):
[error]
[error]   - encountered 1 test failures(s), took 4.157 sec
[error]     at dotty.tools.vulpix.ParallelTesting$CompilationTest.checkCompile(ParallelTesting.scala:959)
[error]     at dotty.tools.dotc.CompilationTests.pos(CompilationTests.scala:101)
[error]     ...
[info] Test dotty.tools.dotc.CompilationTests.tastyBootstrap started
No files matched "inductive-implicits-bench" in test
No files matched "inductive-implicits-bench" in test
No files matched "inductive-implicits-bench" in test
No files matched "inductive-implicits-bench" in test
[info] Test dotty.tools.dotc.CompilationTests.posTwice started
No files matched "inductive-implicits-bench" in test
[info] Test dotty.tools.dotc.CompilationTests.genericJavaSignatures started
No files matched "inductive-implicits-bench" in test

================================================================================
Test Report
================================================================================

0 suites passed, 1 failed, 1 total
    tests/pos-deep-subtype/inductive-implicits-bench.scala failed

[Blaisorblade]

Since it doesn't always fail locally, I expect it might fail or pass depending on how optimized the code is. I'll propose increasing the stack size before bootstrap.