Python 3.8 build fails

[HarrySky]

After commit bd75088ea9b03df1618f1e0b8423a496412ae663 (I guess, because it changes _PyObject_FastCall related code) build fails with this message:

gcc -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -DTHREAD_STACK_SIZE=0x100000 -fPIC -Iast3/Include -I/usr/local/include/python3.8 -c ast3/Python/ast.c -o build/temp.linux-x86_64-3.8/ast3/Python/ast.o
    ast3/Python/ast.c:22:1: error: conflicting types for '_PyObject_FastCall'
     _PyObject_FastCall(PyObject *func, PyObject *const *args, int nargs)
     ^~~~~~~~~~~~~~~~~~
    In file included from /usr/local/include/python3.8/abstract.h:837,
                     from /usr/local/include/python3.8/Python.h:147,
                     from ast3/Python/ast.c:6:
    /usr/local/include/python3.8/cpython/abstract.h:142:1: note: previous definition of '_PyObject_FastCall' was here
     _PyObject_FastCall(PyObject *func, PyObject *const *args, Py_ssize_t nargs)
     ^~~~~~~~~~~~~~~~~~

Environment: Docker Alpine 3.9 Python 3.8 (3.8-rc-alpine3.9)
Related bug report in Red Hat tracker

[gvanrossum]

That's odd, since that definition in typed_ast's ast.c (at line 22) should not be used with Python 3.8. It is inside #if PY_MINOR_VERSION < 6.

What's the value of PY_MINOR_VERSION at that point? (Also, what version of Python 3.8 is being used? beta 1, or the head of upstream cpython's 3.8 branch? Though it probably doesn't matter.)

I cannot repro this in my own environment (Mac).

[apalala]

I can confirm that the build fails with 3.8b1 over pip instally mypy.

[msullivan]

typed-ast 1.3.5 doesn't build on 3.8 but 1.4.0 does. The latest mypy release still depends on <1.4.0, though

[gvanrossum]

So there's nothing for us to do here, right? This will right itself with the next mypy release. Until then, Red Hat can choose to patch mypy's setup.py to allow typed_ast 1.4.0.

[msullivan]

Yeah.

…

On Sat, Jun 15, 2019 at 1:36 PM Guido van Rossum ***@***.***> wrote: So there's nothing for us to do here, right? This will right itself with the next mypy release. Until then, Red Hat can choose to patch mypy's setup.py to allow typed_ast 1.4.0. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#124?email_source=notifications&email_token=AACTC7JDID6HZSBMTRHGAS3P2VHEHA5CNFSM4HYI6Q52YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGODXY7VRI#issuecomment-502397637>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AACTC7JPDK7NT2OK22FRWN3P2VHEHANCNFSM4HYI6Q5Q> .

[soffes]

I ran into this because the latest brew install pre-commit depends on Python 3.8. Bumping mypy to v0.761 in .pre-commit-config.yaml fixed the problem for me.

[rnegron]

Thanks soffes, your solution worked for me :)

[stephensmithlyft]

@soffes Had a pre-commit problem, so I searched conflicting types for '_PyObject_FastCall' on Google, and followed the instructions at the first hit. It was an unexpected delight that the solution to my problems was provided by you! Hope you are well!

[cah-david-weirich]

Thank you @soffes ! This ended two days of headaches for me!

[jcomo]

Hello @stephensmithlyft and @soffes 👋 - I'm equally delighted to see both of you in this thread, and thanks Sam for the fix :)

[soffes]

Haha hi @jcomo 😃

[stephensmithlyft]

Hi @jcomo and thanks again @soffes -- I had to repeat this fix in a different repository last week.