Tasty hardening: Tasty with missing fields in classes isn't detected early enough

[Blaisorblade]

I keep getting, even on master, this failure on local runs:

> testOnly dotty.tools.dotc.FromTastyTests
[info] Cleaning the dotty-sbt-bridge cache
[info] Passed: Total 0, Failed 0, Errors 0, Passed 0
[info] No tests to run for dotty-interfaces/test:testOnly
[info] Passed: Total 0, Failed 0, Errors 0, Passed 0
[info] No tests to run for dotty-library/test:testOnly
[warn] Multiple main classes detected.  Run 'show discoveredMainClasses' to see the list
[info] Passed: Total 0, Failed 0, Errors 0, Passed 0
[info] No tests to run for dotty/test:testOnly
[warn] Multiple main classes detected.  Run 'show discoveredMainClasses' to see the list
[info] Test run started
[info] Test dotty.tools.dotc.FromTastyTests.runTestFromTasty started
[=======================================] completed (944/944, 67s)
[=======================================] completed (898/898, 40s)  s)
[=======================================] completed (1/1, 0s)
[info] Test dotty.tools.dotc.FromTastyTests.posTestFromTasty started
[=======================================] completed (1466/1466, 71s)
undefined: B2.t.f # 6948988: TermRef(TermRef(ThisType(TypeRef(ThisType(TypeRef(ThisType(TypeRef(NoPrefix,module class <root>)),module class <empty>)),module class B2$)),module t),f) at frontend
[=======================================] completed (1362/1362, 33s)
[error] Test dotty.tools.dotc.FromTastyTests.posTestFromTasty failed: java.lang.AssertionError: Expected no errors when compiling, failed for the following reason(s):
[error]
[error]   - encountered 1 error(s), took 104.822 sec
[error]     at dotty.tools.vulpix.ParallelTesting$CompilationTest.checkCompile(ParallelTesting.scala:958)
[error]     at dotty.tools.dotc.FromTastyTests.posTestFromTasty(FromTastyTests.scala:68)
[error]     ...

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

4 passed, 1 failed, 5 total
    tests/pos/overloaded_ho_fun.scala failed


--------------------------------------------------------------------------------
Note - reproduction instructions have been dumped to log file:
    /Users/pgiarrusso/git/dotty/testlogs/tests-2018-04-05/tests-2018-04-05-T21-27-32.log
--------------------------------------------------------------------------------
[info] Test run finished: 1 failed, 0 ignored, 2 total, 214.307s
[error] Failed: Total 2, Failed 1, Errors 0, Passed 1
[error] Failed tests:
[error] 	dotty.tools.dotc.FromTastyTests
[info] Passed: Total 0, Failed 0, Errors 0, Passed 0
[info] No tests to run for dotty-sbt-bridge/test:testOnly
[info] Passed: Total 0, Failed 0, Errors 0, Passed 0
[info] No tests to run for dotty-doc/test:testOnly
[error] (dotty-compiler/test:testOnly) sbt.TestsFailedException: Tests unsuccessful
[error] Total time: 218 s, completed Apr 5, 2018 9:31:08 PM

[Blaisorblade]

Investigation with a debugger suggests, essentially, not enough information has been loaded for retypechecking the loaded tree. Still no clue why this only happens locally — I tried to clean the build deeper and deeper without making a difference. I might still be doing something wrong.

The error appears when loading and typing the tree, in the call to t.f(fun). The issue is that t.f is overloaded but not enough information is there during loading (too many fields are null) to be able to disambiguate the overload.

  object t { def f(x: SAM[Int, Int]): Int = 0; def f(y: SAM[String, Int]): String = "1" }
  def fun(x: Int) = x
  def fun2[T] = (x: T) => 42
  t.f(fun) // different param type, monomorphic method

Details (not sure if helpful)

During loading, in the call to tpd.Apply (and assignType) from TreeUnpickler, t.f's type is a TermRef with Name("f") as myDesignator` and no other info.

Here t.f is in fact overloaded, but the relevant internal data structures are so incomplete that Types.NamedType.disambiguate on the corresponding MultiDenotation fails (== returns NoDenotation), because NamedType.currentSignature finds null signature and denotation and returns NotAMethod, and eventuallycomputeDenot on the TermRef for t.f fails with NoDenotation, which looks not even overloaded.

[allanrenucci]

Try removing the output (i.e. out) directory before running the tests. If this doesn't fix your problem, try running the tests locally after doing git clean -Xfd.

[Blaisorblade]

Tried removing out and target too — now trying the test in a fresh clone (don't want to lose project files).

$ git clone --depth 1 --single-branch dotty dotty-vanilla
$ git submodule update --init
$ sbt 'testOnly dotty.tools.dotc.FromTastyTests' shell

[Blaisorblade]

Got the same error in the fresh clone.

[Blaisorblade]

The test passes for me on Linux, so I'm gonna ask (a) can anybody confirm they can run the test successfully on Mac (if yes, on APFS or HFS+?) (b) could this depend on the order files are read (even though IIRC we should have some code to prevent that issue, or at least Scalac has)?
Think @smarter knows better.

If I'm not still screwing up somehow, I have the setup to walk through the error, so maybe we can look at it together.

[allanrenucci]

Not able to reproduce on latest master with macOS 10.13.4

[Blaisorblade]

So I was screwing up a bit (sorry about that), and #4257 was relevant, but I'll look closer — I think some hardening might be warranted.

[OlivierBlanvillain]

I'm gonna close this for now since it doesn't seam to be reproducible