mypy always fails with Python 3.10 match statement

[wrobell]

Please consider:

a = 1
match a:  # type: ignore
    case 0:
        print('is zero')
    case 1:
        print('is one')

then

$ mypy t5.py
t5.py:2: error: Match statement is not supported
Found 1 error in 1 file (errors prevented further checking)

I would expect Mypy to ignore the whole match block.

Or is there an option I am missing, which I can pass to Mypy?

Mypy 0.930, Python 3.10.1.

[srittau]

The match statement is not yet supported in mypy. See #10191.

[wrobell]

@srittau That's OK. I am just asking Mypy to ignore match block, but it still raises the error.

It seems it could be trivial to make it to respect "type: ignore"?

mypy/mypy/fastparse.py

Lines 1289 to 1293 in 9e34f6a

	def visit_Match(self, n: Any) -> Node:
	self.fail("Match statement is not supported",
	line=n.lineno, column=n.col_offset, blocker=True)
	# Just return some valid node
	return PassStmt()

[srittau]

That indeed seems like a regression. At least in mypy 0.910, the match statement could be ignored.

[jarek-webellian]

@srittau downgraded to mypy 0.910, the error is still the same

$ mypy -V && mypy t5.py
mypy 0.910
t5.py:2: error: Match statement is not supported  [syntax]
Found 1 error in 1 file (errors prevented further checking)

[MPalarya]

@srittau is there a way to properly ignore the match section as a temporary solution?
OP's attempt does not seem to work on either 0.910 and 0.931 versions

[srittau]

I'm not sure. I thought it had worked for me with 0.910, but when I downgraded, it failed too.

[intgr]

Looks like proper match support is pretty close to merging (#10191), so I guess it makes sense to just wait it out?

[JelleZijlstra]

It has been merged

[lenoqt]

When this is going to be available on pypi? I am still having issues with my build using the latest version.

[JelleZijlstra]

There are no concrete plans for the next release yet.

[JukkaL]

I'm hoping that we will have a feature release sometime in February.

[JukkaL]

This issue can be used to track progress on the next feature release which will support the match statement:

• Release 0.940 planning #12021

[schlopp96]

When this is going to be available on pypi? I am still having issues with my build using the latest version.

As have I unfortunately...

I've tried adding # type: ignore to various parts of code blocks just in case perhaps there was some sort of bug causing said phrase to function incorrectly or in different positions, but no dice.

Are there any sort of temporary fixes in the meantime, or do I just need to ignore the red squiggles in my IDE for now, lol?

[lenoqt]

When this is going to be available on pypi? I am still having issues with my build using the latest version.

As have I unfortunately...

I've tried adding # type: ignore to various parts of code blocks just in case perhaps there was some sort of bug causing said phrase to function incorrectly or in different positions, but no dice.

Are there any sort of temporary fixes in the meantime, or do I just need to ignore the red squiggles in my IDE for now, lol?

I had to disable mypy until this gets released.

[gdalmau]

As have I unfortunately...

I've tried adding # type: ignore to various parts of code blocks just in case perhaps there was some sort of bug causing said phrase to function incorrectly or in different positions, but no dice.

Are there any sort of temporary fixes in the meantime, or do I just need to ignore the red squiggles in my IDE for now, lol?

While there is no release you can install mypy on the commit that includes this initial support for match statements:

pip install git+git://github.com/python/mypy.git@9b3147701f054bf8ef42bd96e33153b05976a5e1

The commit above is the first commit after 9b63751 where the CI succeeds.

[jeremytwfortune]

I can absolutely appreciate that mypy needs time to support newer features. I'm confused on the choice here, though, to return an error. What is the reasoning behind classifying the result this way?

[intgr]

I'm relying on mypy to type-check my code. If I'm using language features that mypy does not support, I think it's good to receive a warning in places where I cannot rely on it.

The fact that you couldn't suppress the warning was bad, but probably an honest mistake.

[jeremytwfortune]

Certainly agree with the warning. It would be awkward to just have mypy be silent when it can't process some syntax at all. If the fact that it raises an error was in error, that's certainly my misunderstanding of the issue here. Thanks! 👍

[SerGeRybakov]

As have I unfortunately...
I've tried adding # type: ignore to various parts of code blocks just in case perhaps there was some sort of bug causing said phrase to function incorrectly or in different positions, but no dice.
Are there any sort of temporary fixes in the meantime, or do I just need to ignore the red squiggles in my IDE for now, lol?

While there is no release you can install mypy on the commit that includes this initial support for match statements:

pip install git+git://github.com/python/mypy.git@9b3147701f054bf8ef42bd96e33153b05976a5e1

The commit above is the first commit after 9b63751 where the CI succeeds.

It's good to have an option to install from git branch to local. But it doesn't solve pre-commit hooks problems.
Waiting for a soonest release!

[aomayden]

Any updates on this? I'm using mypy 1.3.0 and this is still throwing the error
error: Pattern matching is only supported in Python 3.10 and greater [syntax]

[hauntsaninja]

That probably means you're not running mypy with Python 3.10 or newer (or you're not actually running mypy 1.3). Try python3.10 -m mypy

[aomayden]

Yes, you're right. I hadn't updated my .mypy.ini from a previous project to state python_version=3.10. Thank you!

[larroy]

I still have this in mypy 1.6.1 for mac.
error: Pattern matching is only supported in Python 3.10 and greater

Python 3.10.13
mypy 1.6.1