Generated code for quantifier accepts incorrect sequence?

[dkegel-fastly]

re -k str -l c -r pcre 'a+$'

generates a function which accepts the sequence a\na, which seems rather wrong...?

This is with the tip of main. Also happens with -l go.

[katef]

Thanks for the report.

$ in pcre (with the default line-ending flag) means "end of text with an optional newline". contrast to \Z which means "end of text", without a newline.

The NFA constructed is:

Because the \n is optional for this particular regular expression, the acceptingness of ((1)) is visible back through the epsilon transitions from (5), (4), and (7). Those states all accept.

This NFA can match by reading a\n entirely on the "any" transition for (2), then match the literal a at the end of your input, without a newline, and then accept on (7).

This matches the behaviour for pcregrep:

; echo -n 'a\na' | pcregrep 'a+$'
a
a

[katef]

Closing this because I believe the behaviour here is correct; please re-open if that's wrong.