Incremental compilation leads to Cyclic Reference Error

[b-studios]

Incrementally recompiling leads to "Cyclic reference" while fresh compilation succeeds.

We consistently hit this issue when touching our own Typer.scala forcing us to always clean; compile which of course takes longer than incrementally compiling.

Compiler version

3.3.1, 3.4.1

Minimized code

I minimized our compiler to only a few lines of code in:

effekt-lang/effekt#446

the full minimized example (not the diff or PR) can be found here

https://github.com/effekt-lang/effekt/tree/34b9e79126db91604df4785aaabace15d154f8cb

Output

[error] -- [E046] Cyclic Error: /private/tmp/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:15:57
[error] 15 |  private[typer] val unification = new Unification(using this)
[error]    |                                                         ^
[error]    |                                Cyclic reference involving class Context
[error]    |
[error]    | longer explanation available when compiling with `-explain`
[error] one error found
[error] (root / Compile / compileIncremental) Compilation failed

Expectation

It should consistently compile or always report the error, if this is indeed a problem.

[odersky]

Thanks for the minimization! Here's a standalone reproducer as a pos test:

1. Take the scala files in the project and put them in one directory, append _1 to every name in front of the .scala extension.
2. Copy Typer_1.scala to Typer_2. scala

Run as pos test.

[odersky]

It works without cyclic errors if unification has an explicit type:

private[typer] val unification: Unification = new Unification(using this)

[b-studios]

Hey thanks for looking into it. Maybe I reduced it too much :(

In the original compiler adding the type annotation to unification does not help and I still get long errors:

[error] -- [E046] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:10:7
[error] 10 |import effekt.source.{AnyPattern, Def, Effectful, IgnorePattern, MatchGuard, MatchPattern, ModuleDecl, Stmt, TagPattern, Term, Tree, resolve, symbol}
[error]    |       ^
[error]    |       Cyclic reference involving class Context
[error]    |
[error]    | longer explanation available when compiling with `-explain`
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:111:23
[error] 111 |        Result(Context.join(thnTpe, elsTpe), guardEffs ++ thnEffs ++ elsEffs)
[error]     |               ^^^^^^^^^^^^
[error]     |value join is not a member of effekt.context.Context - did you mean x$3.bind?
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:121:23
[error] 121 |        Result(Context.join(bodyTpe, defaultTpe), defaultEffs ++ bodyEffs)
[error]     |               ^^^^^^^^^^^^
[error]     |value join is not a member of effekt.context.Context - did you mean x$3.bind?
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:148:61
[error] 148 |        val inferredCap: Captures = annotatedCapture.map { _.resolve }.getOrElse {
[error]     |                                                           ^^^^^^^^^
[error]     |value resolve is not a member of effekt.source.CaptureSet, but could be made available as an extension method.
[error]     |
[error]     |One of the following imports might fix the problem:
[error]     |
[error]     |  import effekt.source.Resolvable.resolve
[error]     |  import effekt.source.resolve
[error]     |
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:149:18
[error] 149 |          Context.freshCaptVar(CaptUnificationVar.InferredBox(l))
[error]     |          ^^^^^^^^^^^^^^^^^^^^
[error]     |          value freshCaptVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:167:81
[error] 167 |        val Result(tpe, effs) = checkOverloadedFunctionCall(c, op, targs map { _.resolve }, vargs, bargs, expected)
[error]     |                                                                               ^^^^^^^^^
[error]     |value resolve is not a member of effekt.source.ValueType, but could be made available as an extension method.
[error]     |
[error]     |One of the following imports might fix the problem:
[error]     |
[error]     |  import effekt.source.Resolvable.resolve
[error]     |  import effekt.source.resolve
[error]     |
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:185:59
[error] 185 |        checkOverloadedFunctionCall(c, t.id, targs map { _.resolve }, vargs, bargs, expected)
[error]     |                                                         ^^^^^^^^^
[error]     |value resolve is not a member of effekt.source.ValueType, but could be made available as an extension method.
[error]     |
[error]     |One of the following imports might fix the problem:
[error]     |
[error]     |  import effekt.source.Resolvable.resolve
[error]     |  import effekt.source.resolve
[error]     |
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:193:75
[error] 193 |        val Result(t, eff) = checkCallTo(c, "function", tpe, targs map { _.resolve }, vargs, bargs, expected)
[error]     |                                                                         ^^^^^^^^^
[error]     |value resolve is not a member of effekt.source.ValueType, but could be made available as an extension method.
[error]     |
[error]     |One of the following imports might fix the problem:
[error]     |
[error]     |  import effekt.source.Resolvable.resolve
[error]     |  import effekt.source.resolve
[error]     |
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:199:65
[error] 199 |        checkOverloadedMethodCall(c, receiver, id, targs map { _.resolve }, vargs, bargs, expected)
[error]     |                                                               ^^^^^^^^^
[error]     |value resolve is not a member of effekt.source.ValueType, but could be made available as an extension method.
[error]     |
[error]     |One of the following imports might fix the problem:
[error]     |
[error]     |  import effekt.source.Resolvable.resolve
[error]     |  import effekt.source.resolve
[error]     |
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:205:38
[error] 205 |        val inferredCapture = Context.freshCaptVar(CaptUnificationVar.RegionRegion(tree))
[error]     |                              ^^^^^^^^^^^^^^^^^^^^
[error]     |          value freshCaptVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:208:28
[error] 208 |        flowingInto(Context.without(inferredCapture, List(reg.capture))) {
[error]     |                    ^^^^^^^^^^^^^^^
[error]     |value without is not a member of effekt.context.Context - did you mean x$3.withFocus?
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:216:47
[error] 216 |          val effect: InterfaceType = h.effect.resolve
[error]     |                                      ^^^^^^^^^^^^^^^^
[error]     |value resolve is not a member of effekt.source.BlockType.BlockTypeRef, but could be made available as an extension method.
[error]     |
[error]     |One of the following imports might fix the problem:
[error]     |
[error]     |  import effekt.source.Resolvable.resolve
[error]     |  import effekt.source.resolve
[error]     |
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:223:39
[error] 223 |        val continuationCapt = Context.freshCaptVar(CaptUnificationVar.HandlerRegion(tree))
[error]     |                               ^^^^^^^^^^^^^^^^^^^^
[error]     |          value freshCaptVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:226:46
[error] 226 |        val continuationCaptHandled = Context.without(continuationCapt, providedCapabilities.map(_.capture))
[error]     |                                      ^^^^^^^^^^^^^^^
[error]     |value without is not a member of effekt.context.Context - did you mean x$3.withFocus?
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:315:23
[error] 315 |        Result(Context.join(tpes: _*), resEff)
[error]     |               ^^^^^^^^^^^^
[error]     |value join is not a member of effekt.context.Context - did you mean x$3.bind?
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:345:56
[error] 345 |      val tpe @ InterfaceType(constructor, targs) = sig.resolve
[error]     |                                                    ^^^^^^^^^^^
[error]     |value resolve is not a member of effekt.source.BlockType.BlockTypeRef, but could be made available as an extension method.
[error]     |
[error]     |One of the following imports might fix the problem:
[error]     |
[error]     |  import effekt.source.Resolvable.resolve
[error]     |  import effekt.source.resolve
[error]     |
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:345:30
[error] 345 |      val tpe @ InterfaceType(constructor, targs) = sig.resolve
[error]     |                              ^
[error]     |                              Recursive value $17$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:345:43
[error] 345 |      val tpe @ InterfaceType(constructor, targs) = sig.resolve
[error]     |                                           ^
[error]     |                                       Recursive value $17$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E006] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:364:17
[error] 364 |            case Effectful(otherTpe, otherEffs2) =>
[error]     |                 ^^^^^^^^^
[error]     |                 Not found: Effectful
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:406:24
[error] 406 |                Context.instantiate(declaredType, targs ++ existentials, cparams.map(cap => CaptureSet(cap))) : @unchecked
[error]     |                ^^^^^^^^^^^^^^^^^^^
[error]     |           value instantiate is not a member of effekt.context.Context
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:405:41
[error] 405 |              val FunctionType(Nil, Nil, vps, bps, tpe, effs) =
[error]     |                                         ^
[error]     |                                       Recursive value $18$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:405:46
[error] 405 |              val FunctionType(Nil, Nil, vps, bps, tpe, effs) =
[error]     |                                              ^
[error]     |                                       Recursive value $18$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:405:51
[error] 405 |              val FunctionType(Nil, Nil, vps, bps, tpe, effs) =
[error]     |                                                   ^
[error]     |                                       Recursive value $18$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:405:56
[error] 405 |              val FunctionType(Nil, Nil, vps, bps, tpe, effs) =
[error]     |                                                        ^
[error]     |                                       Recursive value $18$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E134] Type Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:412:40
[error] 412 |                  annotatedType.foreach(matchDeclared(_, declaredType, param))
[error]     |                                        ^^^^^^^^^^^^^
[error]     |None of the overloaded alternatives of method matchDeclared in object Typer with types
[error]     | (got: effekt.symbols.ValueType, declared: effekt.symbols.ValueType, param:
[error]     |  effekt.source.Param)(using x$4: effekt.context.Context): Unit
[error]     | (got: effekt.symbols.BlockType, declared: effekt.symbols.BlockType, param:
[error]     |  effekt.source.Param)(using x$4: effekt.context.Context): Unit
[error]     |match arguments ((_$16 : effekt.symbols.ValueType), (declaredType : Any), (param : effekt.source.Param.ValueParam))
[error] -- [E134] Type Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:413:26
[error] 413 |                  Context.bind(sym, annotatedType.getOrElse(declaredType))
[error]     |                  ^^^^^^^^^^^^
[error]     |None of the overloaded alternatives of method bind in trait TyperOps with types
[error]     | (p: effekt.symbols.TrackedParam): Unit
[error]     | (p: effekt.symbols.ValueParam): Unit
[error]     | (bs: Map[effekt.symbols.Symbol, effekt.symbols.ValueType]): Unit
[error]     | (s: effekt.symbols.BlockSymbol, capt: effekt.symbols.Captures): Unit
[error]     | (s: effekt.symbols.BlockSymbol, tpe: effekt.symbols.BlockType): Unit
[error]     | (s: effekt.symbols.BlockSymbol, tpe: effekt.symbols.BlockType, capt:
[error]     |  effekt.symbols.Captures): Unit
[error]     | (s: effekt.symbols.ValueSymbol, tpe: effekt.symbols.ValueType): Unit
[error]     |match arguments ((sym : effekt.symbols.ValueParam), B)
[error]     |
[error]     |where:    B is a type variable with constraint >: effekt.symbols.ValueType | (declaredType : Any
[error] -- [E134] Type Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:420:18
[error] 420 |                  matchDeclared(annotatedType, declaredType, param)
[error]     |                  ^^^^^^^^^^^^^
[error]     |None of the overloaded alternatives of method matchDeclared in object Typer with types
[error]     | (got: effekt.symbols.ValueType, declared: effekt.symbols.ValueType, param:
[error]     |  effekt.source.Param)(using x$4: effekt.context.Context): Unit
[error]     | (got: effekt.symbols.BlockType, declared: effekt.symbols.BlockType, param:
[error]     |  effekt.source.Param)(using x$4: effekt.context.Context): Unit
[error]     |match arguments ((annotatedType : effekt.symbols.BlockType), (declaredType : Any), (param : effekt.source.Param.BlockParam))
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:447:24
[error] 447 |                Context.instantiate(declaredType, targs ++ existentials, cparams.map(cap => CaptureSet(cap))) : @unchecked
[error]     |                ^^^^^^^^^^^^^^^^^^^
[error]     |           value instantiate is not a member of effekt.context.Context
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:446:41
[error] 446 |              val FunctionType(Nil, Nil, vps, bps, tpe, effs) =
[error]     |                                         ^
[error]     |                                       Recursive value $20$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:446:46
[error] 446 |              val FunctionType(Nil, Nil, vps, bps, tpe, effs) =
[error]     |                                              ^
[error]     |                                       Recursive value $20$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:446:51
[error] 446 |              val FunctionType(Nil, Nil, vps, bps, tpe, effs) =
[error]     |                                                   ^
[error]     |                                       Recursive value $20$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:446:56
[error] 446 |              val FunctionType(Nil, Nil, vps, bps, tpe, effs) =
[error]     |                                                        ^
[error]     |                                       Recursive value $20$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E134] Type Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:453:40
[error] 453 |                  annotatedType.foreach(matchDeclared(_, declaredType, param))
[error]     |                                        ^^^^^^^^^^^^^
[error]     |None of the overloaded alternatives of method matchDeclared in object Typer with types
[error]     | (got: effekt.symbols.ValueType, declared: effekt.symbols.ValueType, param:
[error]     |  effekt.source.Param)(using x$4: effekt.context.Context): Unit
[error]     | (got: effekt.symbols.BlockType, declared: effekt.symbols.BlockType, param:
[error]     |  effekt.source.Param)(using x$4: effekt.context.Context): Unit
[error]     |match arguments ((_$17 : effekt.symbols.ValueType), (declaredType : Any), (param : effekt.source.Param.ValueParam))
[error] -- [E134] Type Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:454:26
[error] 454 |                  Context.bind(sym, annotatedType.getOrElse(declaredType))
[error]     |                  ^^^^^^^^^^^^
[error]     |None of the overloaded alternatives of method bind in trait TyperOps with types
[error]     | (p: effekt.symbols.TrackedParam): Unit
[error]     | (p: effekt.symbols.ValueParam): Unit
[error]     | (bs: Map[effekt.symbols.Symbol, effekt.symbols.ValueType]): Unit
[error]     | (s: effekt.symbols.BlockSymbol, capt: effekt.symbols.Captures): Unit
[error]     | (s: effekt.symbols.BlockSymbol, tpe: effekt.symbols.BlockType): Unit
[error]     | (s: effekt.symbols.BlockSymbol, tpe: effekt.symbols.BlockType, capt:
[error]     |  effekt.symbols.Captures): Unit
[error]     | (s: effekt.symbols.ValueSymbol, tpe: effekt.symbols.ValueType): Unit
[error]     |match arguments ((sym : effekt.symbols.ValueParam), B)
[error]     |
[error]     |where:    B is a type variable with constraint >: effekt.symbols.ValueType | (declaredType : Any
[error] -- [E051] Reference Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:476:14
[error] 476 |      Context.annotateInferredType(impl, tpe)
[error]     |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error]     |Ambiguous overload. The overloaded alternatives of method annotateInferredType in trait TyperOps with types
[error]     | (t: effekt.source.Tree, e: effekt.symbols.BlockType): Unit
[error]     | (t: effekt.source.Tree, e: effekt.symbols.ValueType): Unit
[error]     |both match arguments ((impl : effekt.source.Implementation), (tpe : Nothing))
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:491:34
[error] 491 |            val captVar = Context.freshCaptVar(CaptUnificationVar.InferredUnbox(u))
[error]     |                          ^^^^^^^^^^^^^^^^^^^^
[error]     |          value freshCaptVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:543:14
[error] 543 |      Context.requireSubtype(sc, lit.tpe, ErrorContext.PatternMatch(p))
[error]     |      ^^^^^^^^^^^^^^^^^^^^^^
[error]     |      value requireSubtype is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:554:60
[error] 554 |      val freshUniversals   = universals.map { t => Context.freshTypeVar(t, pattern) }
[error]     |                                                    ^^^^^^^^^^^^^^^^^^^^
[error]     |          value freshTypeVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:562:55
[error] 562 |      val FunctionType(_, _, vps, _, ret, _) = Context.instantiate(sym.toType, targs, Nil)
[error]     |                                               ^^^^^^^^^^^^^^^^^^^
[error]     |           value instantiate is not a member of effekt.context.Context
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:562:29
[error] 562 |      val FunctionType(_, _, vps, _, ret, _) = Context.instantiate(sym.toType, targs, Nil)
[error]     |                             ^
[error]     |                             Recursive value $23$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:562:37
[error] 562 |      val FunctionType(_, _, vps, _, ret, _) = Context.instantiate(sym.toType, targs, Nil)
[error]     |                                     ^
[error]     |                                     Recursive value $23$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E006] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:582:9
[error] 582 |    case MatchGuard.BooleanGuard(condition) =>
[error]     |         ^^^^^^^^^^
[error]     |         Not found: MatchGuard
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E007] Type Mismatch Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:583:40
[error] 583 |      val Result(tpe, effs) = checkExpr(condition, Some(TBoolean))
[error]     |                                        ^^^^^^^^^
[error]     |                                        Found:    (condition : Any)
[error]     |                                        Required: effekt.source.Term
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:583:17
[error] 583 |      val Result(tpe, effs) = checkExpr(condition, Some(TBoolean))
[error]     |                 ^
[error]     |                 Recursive value $24$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:583:22
[error] 583 |      val Result(tpe, effs) = checkExpr(condition, Some(TBoolean))
[error]     |                      ^
[error]     |                      Recursive value $24$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E006] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:585:9
[error] 585 |    case MatchGuard.PatternGuard(scrutinee, pattern) =>
[error]     |         ^^^^^^^^^^
[error]     |         Not found: MatchGuard
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E007] Type Mismatch Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:586:40
[error] 586 |      val Result(tpe, effs) = checkExpr(scrutinee, None)
[error]     |                                        ^^^^^^^^^
[error]     |                                        Found:    (scrutinee : Any)
[error]     |                                        Required: effekt.source.Term
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:586:17
[error] 586 |      val Result(tpe, effs) = checkExpr(scrutinee, None)
[error]     |                 ^
[error]     |                 Recursive value $25$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:586:22
[error] 586 |      val Result(tpe, effs) = checkExpr(scrutinee, None)
[error]     |                      ^
[error]     |                      Recursive value $25$ needs type
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E007] Type Mismatch Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:587:31
[error] 587 |      Result(checkPattern(tpe, pattern), effs)
[error]     |                               ^^^^^^^
[error]     |                               Found:    (pattern : Any)
[error]     |                               Required: effekt.source.MatchPattern
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:609:40
[error] 609 |          val inferredCapture = Context.freshCaptVar(CaptUnificationVar.VarRegion(d))
[error]     |                                ^^^^^^^^^^^^^^^^^^^^
[error]     |          value freshCaptVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:612:30
[error] 612 |          flowingInto(Context.without(inferredCapture, List(sym.capture))) {
[error]     |                      ^^^^^^^^^^^^^^^
[error]     |value without is not a member of effekt.context.Context - did you mean x$3.withFocus?
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:641:24
[error] 641 |      val cap = Context.freshCaptVar(CaptUnificationVar.FunctionRegion(d))
[error]     |                ^^^^^^^^^^^^^^^^^^^^
[error]     |          value freshCaptVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:651:24
[error] 651 |      val cap = Context.freshCaptVar(CaptUnificationVar.BlockRegion(d))
[error]     |                ^^^^^^^^^^^^^^^^^^^^
[error]     |          value freshCaptVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:722:40
[error] 722 |          val inferredCapture = Context.freshCaptVar(CaptUnificationVar.FunctionRegion(d))
[error]     |                                ^^^^^^^^^^^^^^^^^^^^
[error]     |          value freshCaptVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:824:60
[error] 824 |        given inferredCapture: CaptUnificationVar = Context.freshCaptVar(CaptUnificationVar.BlockRegion(d))
[error]     |                                                    ^^^^^^^^^^^^^^^^^^^^
[error]     |          value freshCaptVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:930:31
[error] 930 |      val bodyRegion = Context.freshCaptVar(CaptUnificationVar.AnonymousFunctionRegion(arg))
[error]     |                       ^^^^^^^^^^^^^^^^^^^^
[error]     |          value freshCaptVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:963:36
[error] 963 |      val inferredCapture = Context.freshCaptVar(CaptUnificationVar.AnonymousFunctionRegion(arg)
[error]     |                            ^^^^^^^^^^^^^^^^^^^^
[error]     |          value freshCaptVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1054:62
[error] 1054 |          case (param :: params, Nil) => ValueTypeRef(Context.freshTypeVar(param, call)) :: fillInTypeArguments(params, Nil)
[error]      |                                                      ^^^^^^^^^^^^^^^^^^^^
[error]      |        value freshTypeVar is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1188:88
[error] 1188 |    val (typeArgs, captArgs, bt @ FunctionType(_, _, vps, bps, ret, retEffs)) = Context.instantiateFresh(funTpe)
[error]      |                                                                                ^^^^^^^^^^^^^^^^^^^^^^^^
[error]      |    value instantiateFresh is not a member of effekt.context.Context
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1188:9
[error] 1188 |    val (typeArgs, captArgs, bt @ FunctionType(_, _, vps, bps, ret, retEffs)) = Context.instantiateFresh(funTpe)
[error]      |         ^
[error]      |         Recursive value $51$ needs type
[error]      |
[error]      | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1188:19
[error] 1188 |    val (typeArgs, captArgs, bt @ FunctionType(_, _, vps, bps, ret, retEffs)) = Context.instantiateFresh(funTpe)
[error]      |                   ^
[error]      |                   Recursive value $51$ needs type
[error]      |
[error]      | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1188:29
[error] 1188 |    val (typeArgs, captArgs, bt @ FunctionType(_, _, vps, bps, ret, retEffs)) = Context.instantiateFresh(funTpe)
[error]      |                             ^
[error]      |                             Recursive value $51$ needs type
[error]      |
[error]      | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1188:53
[error] 1188 |    val (typeArgs, captArgs, bt @ FunctionType(_, _, vps, bps, ret, retEffs)) = Context.instantiateFresh(funTpe)
[error]      |                                                     ^
[error]      |                                     Recursive value $51$ needs type
[error]      |
[error]      | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1188:58
[error] 1188 |    val (typeArgs, captArgs, bt @ FunctionType(_, _, vps, bps, ret, retEffs)) = Context.instantiateFresh(funTpe)
[error]      |                                                          ^
[error]      |                                     Recursive value $51$ needs type
[error]      |
[error]      | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1188:63
[error] 1188 |    val (typeArgs, captArgs, bt @ FunctionType(_, _, vps, bps, ret, retEffs)) = Context.instantiateFresh(funTpe)
[error]      |                                                               ^
[error]      |                                     Recursive value $51$ needs type
[error]      |
[error]      | longer explanation available when compiling with `-explain`
[error] -- [E045] Cyclic Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1188:68
[error] 1188 |    val (typeArgs, captArgs, bt @ FunctionType(_, _, vps, bps, ret, retEffs)) = Context.instantiateFresh(funTpe)
[error]      |                                                                    ^
[error]      |                                     Recursive value $51$ needs type
[error]      |
[error]      | longer explanation available when compiling with `-explain`
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1317:6
[error] 1317 |    C.requireSubregion(c, current)
[error]      |    ^^^^^^^^^^^^^^^^^^
[error]      |    value requireSubregion is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1329:6
[error] 1329 |    C.requireSubregion(from, to)
[error]      |    ^^^^^^^^^^^^^^^^^^
[error]      |    value requireSubregion is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1335:6
[error] 1335 |    C.requireSubregionWithout(from, to, filter)
[error]      |    ^^^^^^^^^^^^^^^^^^^^^^^^^
[error]      |value requireSubregionWithout is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1342:14
[error] 1342 |      Context.requireSubtype(got, declared,
[error]      |      ^^^^^^^^^^^^^^^^^^^^^^
[error]      |      value requireSubtype is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1347:14
[error] 1347 |      Context.requireSubtype(got, declared,
[error]      |      ^^^^^^^^^^^^^^^^^^^^^^
[error]      |      value requireSubtype is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1352:12
[error] 1352 |    Context.requireSubtype(scrutinee, patternTpe, ErrorContext.PatternMatch(pattern))
[error]      |    ^^^^^^^^^^^^^^^^^^^^^^
[error]      |    value requireSubtype is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1355:12
[error] 1355 |    Context.requireSubtype(got, expected,
[error]      |    ^^^^^^^^^^^^^^^^^^^^^^
[error]      |    value requireSubtype is not a member of effekt.context.Context
[error] -- [E008] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1359:12
[error] 1359 |    Context.requireSubtype(got, expected,
[error]      |    ^^^^^^^^^^^^^^^^^^^^^^
[error]      |    value requireSubtype is not a member of effekt.context.Context
[error] -- [E006] Not Found Error: /Users/jonathan/Desktop/github/effekt/effekt/shared/src/main/scala/effekt/Typer.scala:1639:30
[error] 1639 |    var capturesForLSP: List[(Tree, CaptureSet)] = Nil
[error]      |                              ^^^^
[error]      |                              Not found: type Tree
[error]      |
[error]      | longer explanation available when compiling with `-explain`
[error] 76 errors found

The spurious Recursive value $25$ needs type are confusing. They are not really recursive.

[odersky]

I added some more diagnostics in #20251. You need to compile with -explain-cyclic then that gives hopefully more info.

It's unfortunately not feasible to ensure that cyclic errors appear independent of compilation order.

Also, messages after the first "Cyclic Reference" should usually be ignored. Once a cyclic reference happens all bets are off and follow-on errors are expected.

[odersky]

@b-studios Did you compile the project with -explain-cyclic? Any new insights what might be the cause? If not I could take a look at the error trace. Ideally, with -explain-cyclic and -Ydebug-cyclic both set.