Fix issue #2958 - deduplicate (anonymous) tasks in result

[lefou]

Anonymous tasks can be defined as val or def. This is in contrast to named targets, which always need to be defined as def.

Also, anonymous tasks end up in the terminal group of the target that's using them.

If the same anonymous task is used in multiple targets, it also ends up multiple time in the task results. When a Evaluator.Results is created, this clashes, due to the use of a Strict.Agg for Evalutor.Results.evaluated.

This change deduplicated the results before constructing the Evaluator.Results.

Fix: #2958

[lihaoyi]

So as far as I can tell, evaluated: Agg[Task[_]] is only used in the test suite, and transitive: Agg[Task[_]] is not used at all. So this should be fine from a runtime behavior perspective. And anyway it's private[mill] so we change things without worrying about compatibility.

As for what the correct thing to do here is, Strict.Agg.from(Loose.Agg.from(can just be a single.distinct` call I think. Then maybe just a comment and a simple test case illustrating the edge case and then we should be good to go

[lefou]

My new test fails on Windows, but I have no idea why.

[#1] [#1] [#3] [#00] mill.eval.SeqTaskTests: [1/3] repro2958.task2 
[#1] [#1] [#3] [#00] mill.eval.SeqTaskTests: [2/3] repro2958.task3 
[#1] [#1] [#3] [#00] mill.eval.SeqTaskTests: [3/3] repro2958.com1 
X mill.eval.SeqTaskTests.duplicateTaskInResult-issue2958 4ms 
  java.nio.file.NoSuchFileException: D:\a\mill\mill\target\workspace\mill\eval\SeqTaskTests\check\duplicateTaskInResult-issue2958\SeqTaskTests$\repro2958\com1.json
    sun.nio.fs.WindowsException.translateToIOException(WindowsException.java:79)
    sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:97)
    sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:102)
    sun.nio.fs.WindowsFileSystemProvider.newByteChannel(WindowsFileSystemProvider.java:230)
    java.nio.file.Files.newByteChannel(Files.java:361)
    os.write$.write(ReadWriteOps.scala:64)
    os.write$over$.apply(ReadWriteOps.scala:142)
    mill.eval.GroupEvaluator.$anonfun$handleTaskResult$2(GroupEvaluator.scala:406)
    mill.eval.GroupEvaluator.$anonfun$handleTaskResult$2$adapted(GroupEvaluator.scala:405)
    scala.Option.foreach(Option.scala:437)
    mill.eval.GroupEvaluator.handleTaskResult(GroupEvaluator.scala:405)
    mill.eval.GroupEvaluator.evaluateGroupCached(GroupEvaluator.scala:226)
    mill.eval.GroupEvaluator.evaluateGroupCached$(GroupEvaluator.scala:45)
    mill.eval.EvaluatorImpl.evaluateGroupCached(EvaluatorImpl.scala:15)
    mill.eval.EvaluatorCore.$anonfun$evaluate0$2(EvaluatorCore.scala:116)
    scala.concurrent.impl.Promise$Transformation.run(Promise.scala:467)
    mill.eval.ExecutionContexts$RunNow$.execute(ExecutionContexts.scala:13)
    scala.concurrent.impl.Promise$Transformation.submitWithValue(Promise.scala:429)
    scala.concurrent.impl.Promise$DefaultPromise.submitWithValue(Promise.scala:338)
    scala.concurrent.impl.Promise$DefaultPromise.dispatchOrAddCallbacks(Promise.scala:312)
    scala.concurrent.impl.Promise$DefaultPromise.map(Promise.scala:182)
    mill.eval.EvaluatorCore.$anonfun$evaluate0$1(EvaluatorCore.scala:92)
    mill.eval.EvaluatorCore.$anonfun$evaluate0$1$adapted(EvaluatorCore.scala:90)
    scala.collection.immutable.Vector.foreach(Vector.scala:2124)
    mill.eval.EvaluatorCore.evaluate0(EvaluatorCore.scala:90)
    mill.eval.EvaluatorCore.$anonfun$evaluate$1(EvaluatorCore.scala:43)
    scala.util.DynamicVariable.withValue(DynamicVariable.scala:59)
    mill.eval.EvaluatorCore.evaluate(EvaluatorCore.scala:34)
    mill.eval.EvaluatorCore.evaluate$(EvaluatorCore.scala:26)
    mill.eval.EvaluatorImpl.evaluate(EvaluatorImpl.scala:15)
    mill.testkit.MillTestKit$TestEvaluator.apply(MillTestkit.scala:128)
    mill.testkit.MillTestKit$TestEvaluator.apply(MillTestkit.scala:121)
    mill.eval.TaskTests.$anonfun$tests$34(TaskTests.scala:257)
    mill.eval.TaskTests.$anonfun$tests$34$adapted(TaskTests.scala:256)
    mill.eval.SeqTaskTests$.withEnv(TaskTests.scala:271)
    mill.eval.TaskTests.$anonfun$tests$33(TaskTests.scala:137)

[lihaoyi]

@lefou is it because your target starts with the word com which is prohibited on the windows filesystem?

[lefou]

@lefou is it because your target starts with the word com which is prohibited on the windows filesystem?

Thanks for the hint. In fact, it's the exact name "com1" that is reserved, although I wonder why the file name extension isn't counted as part of the name.

There are other reserved names, which we should try to detect and handle somehow in Mill, to avoid misleading error messages: CON, PRN, AUX, NUL, COM0, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9, COM¹, COM², COM³, LPT0, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, LPT9, LPT¹, LPT², and LPT³

• Source: https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file?redirectedfrom=MSDN#naming-conventions