PEP 695 syntax breaks parsing of forward type reference
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Description
Problem Description
Python 3.12 introduced PEP 695 Type Parameter Syntax. This seems to break type parsing for a forward type reference to a generic class in a method of another generic class:
class Foo[T]:
def foo(self) -> "Bar[T]": # this breaks!
...
class Bar[T]:
def bar(self, _: T) -> None:
...
That is a valid Python 3.12 module, but running pdoc on it will result in:
Error parsing type annotation Bar[T] for package.module.Foo.foo. Import of T failed: name 'T' is not defined
The generated HTML therefore does not have a link:
<span class="return-annotation">) -> <span class="s1">'Bar[T]'</span>:</span>
Steps to reproduce the behavior:
Run pdoc on a package containing the example module above.
Note that using the old syntax does not break parsing, probably because it requires a TypeVar to be defined:
from typing import Generic, TypeVar
T = TypeVar("T")
class Foo(Generic[T]):
def foo(self) -> "Bar[T]": # this is fine
...
class Bar(Generic[T]):
def bar(self, _: T) -> None:
...
Note also that the problem only occurs with a forward reference, insofar as the following example does not break parsing either:
class Foo[T]:
def foo(self, _: T) -> None:
...
class Bar[T]:
def bar(self) -> Foo[T]: # this is fine
...
System Information
pdoc: 15.0.0
Python: 3.12.7
Platform: Linux-6.1.0-21-amd64-x86_64-with-glibc2.36
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the issue with the PEP 695 example module and running pdoc on it. Trace the type-annotation parsing for the forward reference in Foo.foo; done means the generated HTML links Bar[T] without reporting that T cannot be imported, while existing examples continue to parse.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- documentation
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 42/100