Does not parse Literal[-1] or other negative literals

[gegnew]

Describe the bug
I have a constant in my package's base __init__.py like:

CONSTANT: Literal[-1] = -1
"""
docstring
"""

It's pulled into mkdocs through the doc_file.md in mkdocs.yml, and in doc_file.md with:

::: package.CONSTANT

I get an error when building or serving (error logs at bottom)

Expected behavior
package.CONSTANT: Literal[-1] = -1 in the docs

System (please complete the following information):

• griffe version: 0.19.1

• Python version: 3.9.12

• OS: Linux

  ERROR    -  Error reading page 'api_client.md': <class 'ast.USub'>
  Traceback (most recent call last):
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/bin/mkdocs", line 8, in <module>
      sys.exit(cli())
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/click/core.py", line 1130, in __call__
      return self.main(*args, **kwargs)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/click/core.py", line 1055, in main
      rv = self.invoke(ctx)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/click/core.py", line 1657, in invoke
      return _process_result(sub_ctx.command.invoke(sub_ctx))
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/click/core.py", line 1404, in invoke
      return ctx.invoke(self.callback, **ctx.params)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/click/core.py", line 760, in invoke
      return __callback(*args, **kwargs)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/mkdocs/__main__.py", line 181, in serve_command
      serve.serve(dev_addr=dev_addr, livereload=livereload, watch=watch, **kwargs)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/mkdocs/commands/serve.py", line 63, in serve
      config = builder()
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/mkdocs/commands/serve.py", line 58, in builder
      build(config, live_server=live_server, dirty=dirty)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/mkdocs/commands/build.py", line 292, in build
      _populate_page(file.page, config, files, dirty)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/mkdocs/commands/build.py", line 174, in _populate_page
      page.render(config, files)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/mkdocs/structure/pages.py", line 175, in render
      self.content = md.convert(self.markdown)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/markdown/core.py", line 264, in convert
      root = self.parser.parseDocument(self.lines).getroot()
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/markdown/blockparser.py", line 90, in parseDocument
      self.parseChunk(self.root, '\n'.join(lines))
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/markdown/blockparser.py", line 105, in parseChunk
      self.parseBlocks(parent, text.split('\n\n'))
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/markdown/blockparser.py", line 123, in parseBlocks
      if processor.run(parent, blocks) is not False:
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/mkdocstrings/extension.py", line 120, in run
      html, handler, data = self._process_block(identifier, block, heading_level)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/mkdocstrings/extension.py", line 182, in _process_block
      data: CollectorItem = handler.collector.collect(identifier, selection)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/mkdocstrings_handlers/python/collector.py", line 77, in collect
      loader.load_module(module_name)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/loader.py", line 148, in load_module
      top_module = self._load_module(package.name, package.path, submodules=submodules)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/loader.py", line 346, in _load_module
      return self._load_module_path(module_name, module_path, submodules, parent)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/loader.py", line 368, in _load_module_path
      module = self._visit_module(code, module_name, module_path, parent)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/loader.py", line 407, in _visit_module
      module = visit(
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/visitor.py", line 92, in visit
      return Visitor(
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/visitor.py", line 172, in get_module
      self.visit(top_node)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/visitor.py", line 183, in visit
      super().visit(node)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/base.py", line 19, in visit
      getattr(self, f"visit_{node.kind}", self.generic_visit)(node)  # type: ignore[attr-defined]
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/visitor.py", line 214, in visit_module
      self.generic_visit(node)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/visitor.py", line 196, in generic_visit
      self.visit(child)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/visitor.py", line 183, in visit
      super().visit(node)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/base.py", line 19, in visit
      getattr(self, f"visit_{node.kind}", self.generic_visit)(node)  # type: ignore[attr-defined]
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/visitor.py", line 597, in visit_annassign
      self.handle_attribute(node, get_annotation(node.annotation, parent=self.current))
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/nodes.py", line 754, in get_annotation
      return _get_annotation(node, parent)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/nodes.py", line 739, in _get_annotation
      return _node_annotation_map[type(node)](node, parent)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/nodes.py", line 679, in _get_subscript_annotation
      subscript = _get_annotation(node.slice, parent)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/nodes.py", line 739, in _get_annotation
      return _node_annotation_map[type(node)](node, parent)
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/nodes.py", line 688, in _get_unaryop_annotation
      return Expression(_get_annotation(node.op, parent), _get_annotation(node.operand, parent))
    File "/home/g/Desktop/primity/cellengine-python-toolkit/.direnv/python-3.9.12/lib/python3.9/site-packages/griffe/agents/nodes.py", line 739, in _get_annotation
      return _node_annotation_map[type(node)](node, parent)
  KeyError: <class 'ast.USub'>
  

[pawamoy]

Hi, thanks for the report, this should be fixed in 0.19.3 🙂