Fix constraint cache and unexpected generalizations in BbML #305
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LPTK
reviewed
May 2, 2025
I think the real wrong place is here: abstract class TypeExt extends Type:
// ...
override def equals(that: Any): Bool =
toBasic === thatIf the RHS is not a basic type, we cannot retrieve the constraint from the cache, leading to a stack overflow. Here is the hash set dumped when we solve the constraint HashSet(
(Conj(Inter(None),Union(None,List()),List((InfVar(1,97,hkmc2.bbml.VarState@6e9f9e57,false),true))),NegType(ComposedType(ClassLikeType(class:Cons‹1054›,List(Wildcard(hkmc2.bbml.Bot$@14189e29,NegType(hkmc2.bbml.Bot$@14189e29)), Wildcard(hkmc2.bbml.Bot$@14189e29,NegType(hkmc2.bbml.Bot$@14189e29)))),NegType(ComposedType(ClassLikeType(class:Cons‹1054›,List(Wildcard(InfVar(1,105,hkmc2.bbml.VarState@922ccdb,false),InfVar(1,106,hkmc2.bbml.VarState@4dcb19ef,false)), Wildcard(InfVar(1,107,hkmc2.bbml.VarState@606a2aed,false),InfVar(1,108,hkmc2.bbml.VarState@3349dd58,false)))),ClassLikeType(class:Nil‹1052›,List()),true)),false))),
(InfVar(1,97,hkmc2.bbml.VarState@6e9f9e57,false),InfVar(1,103,hkmc2.bbml.VarState@662f0df5,false)),
(Conj(Inter(None),Union(None,List()),List((InfVar(1,99,hkmc2.bbml.VarState@62b2702b,false),true))),NegType(ComposedType(ClassLikeType(class:Cons‹1054›,List(Wildcard(hkmc2.bbml.Bot$@14189e29,NegType(hkmc2.bbml.Bot$@14189e29)), Wildcard(hkmc2.bbml.Bot$@14189e29,NegType(hkmc2.bbml.Bot$@14189e29)))),NegType(ComposedType(ClassLikeType(class:Cons‹1054›,List(Wildcard(InfVar(1,105,hkmc2.bbml.VarState@922ccdb,false),InfVar(1,106,hkmc2.bbml.VarState@4dcb19ef,false)), Wildcard(InfVar(1,107,hkmc2.bbml.VarState@606a2aed,false),InfVar(1,108,hkmc2.bbml.VarState@3349dd58,false)))),ClassLikeType(class:Nil‹1052›,List()),true)),false))),
(Conj(Inter(None),Union(None,List()),List((InfVar(1,99,hkmc2.bbml.VarState@62b2702b,false),true))),NegType(ComposedType(NegType(hkmc2.bbml.Bot$@14189e29),NegType(InfVar(1,103,hkmc2.bbml.VarState@662f0df5,false)),false))),
(Conj(Inter(None),Union(None,List()),List((InfVar(1,97,hkmc2.bbml.VarState@6e9f9e57,false),true))),InfVar(1,103,hkmc2.bbml.VarState@662f0df5,false)),
(Conj(Inter(None),Union(None,List()),List((InfVar(1,99,hkmc2.bbml.VarState@62b2702b,false),true))),InfVar(1,103,hkmc2.bbml.VarState@662f0df5,false)),
(InfVar(1,99,hkmc2.bbml.VarState@62b2702b,false),NegType(Conj(Inter(Some(ClassLikeType(class:Cons‹1054›,List(Wildcard(Disj(List()),Disj(List(Conj(Inter(None),Union(None,List()),List())))), Wildcard(Disj(List()),Disj(List(Conj(Inter(None),Union(None,List()),List())))))))),Union(None,List(ClassLikeType(class:Cons‹1054›,List(Wildcard(InfVar(1,105,hkmc2.bbml.VarState@922ccdb,false),InfVar(1,106,hkmc2.bbml.VarState@4dcb19ef,false)), Wildcard(InfVar(1,107,hkmc2.bbml.VarState@606a2aed,false),InfVar(1,108,hkmc2.bbml.VarState@3349dd58,false)))), ClassLikeType(class:Nil‹1052›,List()))),List()))),
(InfVar(1,97,hkmc2.bbml.VarState@6e9f9e57,false),NegType(Conj(Inter(Some(ClassLikeType(class:Cons‹1054›,List(Wildcard(Disj(List()),Disj(List(Conj(Inter(None),Union(None,List()),List())))), Wildcard(Disj(List()),Disj(List(Conj(Inter(None),Union(None,List()),List())))))))),Union(None,List(ClassLikeType(class:Cons‹1054›,List(Wildcard(InfVar(1,105,hkmc2.bbml.VarState@922ccdb,false),InfVar(1,106,hkmc2.bbml.VarState@4dcb19ef,false)), Wildcard(InfVar(1,107,hkmc2.bbml.VarState@606a2aed,false),InfVar(1,108,hkmc2.bbml.VarState@3349dd58,false)))), ClassLikeType(class:Nil‹1052›,List()))),List()))),
(InfVar(1,97,hkmc2.bbml.VarState@6e9f9e57,false),NegType(Conj(Inter(Some(ClassLikeType(class:Cons‹1054›,List(Wildcard(Disj(List()),Disj(List(Conj(Inter(None),Union(None,List()),List())))), Wildcard(Disj(List()),Disj(List(Conj(Inter(None),Union(None,List()),List())))))))),Union(None,List(ClassLikeType(class:Cons‹1054›,List(Wildcard(InfVar(1,105,hkmc2.bbml.VarState@922ccdb,false),InfVar(1,106,hkmc2.bbml.VarState@4dcb19ef,false)), Wildcard(InfVar(1,107,hkmc2.bbml.VarState@606a2aed,false),InfVar(1,108,hkmc2.bbml.VarState@3349dd58,false)))), ClassLikeType(class:Nil‹1052›,List()))),List()))),
(InfVar(1,97,hkmc2.bbml.VarState@6e9f9e57,false),NegType(Conj(Inter(Some(ClassLikeType(class:Cons‹1054›,List(Wildcard(Disj(List()),Disj(List(Conj(Inter(None),Union(None,List()),List())))), Wildcard(Disj(List()),Disj(List(Conj(Inter(None),Union(None,List()),List())))))))),Union(None,List(ClassLikeType(class:Cons‹1054›,List(Wildcard(InfVar(1,105,hkmc2.bbml.VarState@922ccdb,false),InfVar(1,106,hkmc2.bbml.VarState@4dcb19ef,false)), Wildcard(InfVar(1,107,hkmc2.bbml.VarState@606a2aed,false),InfVar(1,108,hkmc2.bbml.VarState@3349dd58,false)))), ClassLikeType(class:Nil‹1052›,List()))),List()))),
(ComposedType(Disj(List(Conj(Inter(None),Union(None,List()),List((InfVar(1,99,hkmc2.bbml.VarState@62b2702b,false),true))))),Disj(List(Conj(Inter(None),Union(None,List()),List()))),false),InfVar(1,108,hkmc2.bbml.VarState@3349dd58,false)),
(ComposedType(Disj(List(Conj(Inter(None),Union(None,List()),List((InfVar(1,99,hkmc2.bbml.VarState@62b2702b,false),true))))),Disj(List(Conj(Inter(None),Union(None,List()),List()))),false),InfVar(1,108,hkmc2.bbml.VarState@3349dd58,false)),
(Conj(Inter(None),Union(None,List()),List((InfVar(1,99,hkmc2.bbml.VarState@62b2702b,false),true))),InfVar(1,108,hkmc2.bbml.VarState@3349dd58,false)),
(Conj(Inter(None),Union(None,List()),List((InfVar(1,99,hkmc2.bbml.VarState@62b2702b,false),true))),InfVar(1,108,hkmc2.bbml.VarState@3349dd58,false)),
(ClassLikeType(class:Cons‹1054›,List(InfVar(1,98,hkmc2.bbml.VarState@14f0f18b,false), InfVar(1,99,hkmc2.bbml.VarState@62b2702b,false))),NegType(Conj(Inter(Some(ClassLikeType(class:Cons‹1054›,List(Wildcard(Disj(List()),Disj(List(Conj(Inter(None),Union(None,List()),List())))), Wildcard(Disj(List()),Disj(List(Conj(Inter(None),Union(None,List()),List())))))))),Union(None,List(ClassLikeType(class:Cons‹1054›,List(Wildcard(InfVar(1,105,hkmc2.bbml.VarState@922ccdb,false),InfVar(1,106,hkmc2.bbml.VarState@4dcb19ef,false)), Wildcard(InfVar(1,107,hkmc2.bbml.VarState@606a2aed,false),InfVar(1,108,hkmc2.bbml.VarState@3349dd58,false)))), ClassLikeType(class:Nil‹1052›,List()))),List()))),
(ClassLikeType(class:Cons‹1054›,List(InfVar(1,98,hkmc2.bbml.VarState@14f0f18b,false), InfVar(1,99,hkmc2.bbml.VarState@62b2702b,false))),NegType(Conj(Inter(Some(ClassLikeType(class:Cons‹1054›,List(Wildcard(Disj(List()),Disj(List(Conj(Inter(None),Union(None,List()),List())))), Wildcard(Disj(List()),Disj(List(Conj(Inter(None),Union(None,List()),List())))))))),Union(None,List(ClassLikeType(class:Cons‹1054›,List(Wildcard(InfVar(1,105,hkmc2.bbml.VarState@922ccdb,false),InfVar(1,106,hkmc2.bbml.VarState@4dcb19ef,false)), Wildcard(InfVar(1,107,hkmc2.bbml.VarState@606a2aed,false),InfVar(1,108,hkmc2.bbml.VarState@3349dd58,false)))), ClassLikeType(class:Nil‹1052›,List()))),List())))
)I think we can cache normalized types, but we still need to remove this overridden |
|
Oh yeah that |
NeilKleistGao
changed the title
LPTK
reviewed
May 12, 2025
| @@ -283,7 +284,8 @@ class BBTyper(using elState: Elaborator.State, tl: TL): | |||
| val funTy = tryMkMono(res, lam) | |||
| given CCtx = CCtx.init(lam, N) | |||
| constrain(funTy, funTyV)(using ctx) | |||
| pctx += sym -> PolyType.generalize(funTy, S(outer), 1) | |||
| if pctx.isTopLevel then // only generalize top-level definitions | |||
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Do we really need to go to such extreme? Normally the point of keeping track of levels is so that we can still generalize local functions. Is the root problem here that you forgot to increase the level of a function's definition when type checking it?
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Of course, f is at a higher level, and the context level is increased in ctx.nestWithOuter. When type checking fun f(y) = x(y), we have y: 'y, x: 'x, and 'x <: 'y -> 'a for some fresh type variable 'a. After extrusion, x is typed to 'y0 -> 'a0, where 'y <: 'y0 and 'a0 <: 'a since 'y and 'a are not skolem. When type checking f(0), we instantiate 'y and 'a to fresh variables instead of continuing to constrain them because f is generalized. Therefore, x still has no bound.
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What's the point of increasing the level if we're not going to generalize it? 🤔
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Bugs found by @auht.
.toBasic. Also improved type printing in error messages.