Mypy does not accept mmap object in re.match

[libre-man]

It seems that the re.compile types are to restrictive, the following code errors in mypy but running it is no problem:

# _txt_fmt is a object gotten from `re.compile`
with open(file, 'r+') as f:
    with mmap.mmap(f.fileno(), 0) as data:
        match = _txt_fmt.match(data)

Mypy gives the error Argument 1 to "match" of "Pattern" has incompatible type "mmap"; expected "bytes".

[srittau]

Full example:

import mmap
import re

with open("...", 'r+') as f:
    with mmap.mmap(f.fileno(), 0) as data:
        match = re.compile(b"").match(data)

The mmap documentation explicitly mentions the interaction with re: "You can use mmap objects in most places where bytearray are expected; for example, you can use the re module to search through a memory-mapped file." So I believe we should fix this.

[pavel-kalmykov]

Hello. Any update on this?

[srittau]

PR welcome!

[itaisteinherz]

I'd like to work on this.

[JelleZijlstra]

Should be fixed with #7679.