Wrong calculation of generic type returned from lambda

Assuming we have

public void createTextEdit(Range range, String edit){
    return For(Option(range), Option(edit))
       .yield(TextEdit::new);
}

jdt would suggest change method return type to Option<Object> while expected Option<TextEdit>.

Same with .yield((r,d) -> new TextEdit(r,d))

P.S. Option and For…yield from https://www.vavr.io/ , Range and TextEdit from eclipse lsp4j

[testforstephen]

This is a type inference problem introduced by the upstream ECJ (Eclipse Compiler for Java). We also found some generic type use cases where ECJ inferred a different expected type than javac. We’re trying to fix these inconsistencies in the upstream ECJ.

[testforstephen]

I can reproduce it with your latest sample. Looks like a “wildcard capture” problem for generic type inference. Need look deeper for more details.