Possible compiler bug causing LambdaConversionException

[Remi Forax]

Thanks, this is clearly a bug. 

The second call infer T as the intersection type Record & Term, which is erased to Record. 
Term.Lam::new is translated to an invokedynamic 
Method arguments: 
#49 (Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object; 
#50 REF_newInvokeSpecial Bug$Term$Lam."<init>":(Ljava/lang/String;LBug$Term;)V 
#56 (Ljava/lang/String;Ljava/lang/Record;)Ljava/lang/Record; 

This is a case where the compiler should desugar the method reference to a lambda with an upcast from Record to Term 
call ((String x, Record t) -> new Lam(x, (Term) t), "x" , new Term.Lit()); 

but tries to directly reference the constructor thus fails at runtime because the upcast is missing. 

regards, 
Rémi 

> From: "Kiva" <imkiva at islovely.icu>
> To: "compiler-dev" <compiler-dev at openjdk.org>
> Sent: Friday, August 26, 2022 11:04:19 AM
> Subject: Possible compiler bug causing LambdaConversionException

> Hi all,

> I am not sure whether this should be reported to amber-dev or compiler-dev so I
> am reporting it here (sorry!)

> A minimal repro was attached below or you can visit here:
> https://gist.github.com/imkiva/8db13b6e578e473c1c9b977086bfe898

> import java.util.function.BiFunction;

> public class Bug {

> sealed interface Term {

> record Lit() implements Term {}

> record Lam(String x, Term a) implements Term {}

> }

> public static <X, T> void call(BiFunction<X, T, T> op, X x, T t) {

> op.apply(x, t);

> }

> public static void main(String[] args) {

> // this code works

> call(Term.Lam::new, "x", (Term) new Term.Lit());

> // this does not

> call(Term.Lam::new, "x", new Term.Lit());

> // java.lang.invoke.LambdaConversionException: Type mismatch for lambda argument
> 1:

> // class java.lang.Record is not convertible to interface Term

> }

> }
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