About the unconditional_recursion warning in primitives.rs about combine HOT 6 CLOSED

Yes he is, there should be another deref there. Thanks for noticing. I never actually tested boxed parsers since I did not have any need for them. Box trait objects should be useful but it seems that there may be another bug for them rust-lang/rust#21379.
Fixed in 20d35d2.

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OK. Isn't this the same case just above? https://github.com/Marwes/parser-combinators/blob/20d35d26527e9c7edcb5d3632d21bd2b7782d5a7/src/primitives.rs#L227

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Nope, there is a &mut P there which gives

*(&mut P)  == P

The bug was because of &mut Box

*(&mut Box<P>) == Box<P> (which derefs to &mut Box<P> again) 
**(&mut Box<P>) == P

Edit: The reasoning above is slightly wrong but there is still not infinite recursion in the first case

*(&mut &mut P)  == &mut P (which chooses the function for P)

Arguably there should be another deref to be clearer though

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I see. I think I had something like this in some code where I played with box myself and did not recognize this pattern there. Thank you for the explanation!

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Lots of edits there sorry, my brain didn't keep up with the typing since I already knew that there is no issue since I am using the &mut P impl in a few places.

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What I took out of it is the part that if it is "borrow boxed" there are two * needed to get to the content.

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