Given the following code:

class MyClass(object):

    @property
    def my_function(self): pass

Parsing it with ast module, the lineno and col_offset of the ast.FunctionDef is reported to be where the decorator starts (i.e. line 3 column 4) rather than where the actual def statement is (i.e. line 4 column 4).

This is due to the decorator that is part of the ast.FunctionDef, but as  there can be multiple decorators (which they don't provide their own lineno and col_offset arguments) and they can span across multiple lines, there is no reliable way to actually know where the actual def statement starts physically.

See this bug report on flake8-builtins plugin (I'm the author) reported by @dhood user on github:

https://github.com/gforcada/flake8-builtins/issues/22#issuecomment-377961642