Indentation error while parsing version-conditional imports

[achimnol]

With autodoc (.. automodule:: ...),

if sys.version_info < (3, 8, 0):
    from typing_extensions import Literal  # this line
else:
    from typing import Literal

causes "expected indented block" error.

To Reproduce
Steps to reproduce the behavior:

<Paste your command-line here which cause the problem>

$ git clone https://github.com/achimnol/aiotools
$ cd aiotools
$ pip install -r requirements/dev.txt
$ cd docs
$ make html

Expected behavior
It should build the docs.

Screenshots

Environment info

• OS: Linux (Ubuntu 20.04)
• Python version: 3.9.5
• Sphinx version: 4.0.1, 4.1.0dev installed from GitHub
• Sphinx extensions: sphinx.ext.autodoc, sphinx_autodoc_typehints

[cblegare]

Got a similar error when I have class definitions nested in functions

def some_function():
    class SomeClass:
        pass

Extension error (sphinx_autodoc_typehints):
Handler <function process_docstring at 0x7f943cb6c9d0> for event 'autodoc-process-docstring' threw an exception (exception: expected an indented block (<unknown>, line 4))

[cblegare]

Found the root cause in my case. To reproduce, document an async function wih a nested function definition.

Example

async def async_function():
    class InnerClass:
        def __init__(self): pass

the normalize_source_lines function does not detect async def as a function definition., thus provide invalid python as output:

        
        async def async_function():
            class InnerClass:
        def __init__(self): pass
        

I'll try to submit a quick PR about this..

@achimnol that might fix it fr you too

[cblegare]

#182

[achimnol]

This is still happening with Sphinx 4.3 and sphinx-autodoc-typehints 1.12.0, on Python 3.10.
@cblegare's PR is about fixing the issue only for async def lines, but my issue is unrelated with them but just a version-conditional import. Changing my import statement to use try: ... except ImportError: ... gives me the same error.

[gaborbernat]

A PR for this would we welcome.