typing: fix getfslineno

Closes https://github.com/pytest-dev/pytest/pull/6590.

src/_pytest/_code/source.py

@@ -8,6 +8,7 @@ import warnings
 from bisect import bisect_right
 from types import CodeType
 from types import FrameType
+from typing import Any
 from typing import Iterator
 from typing import List
 from typing import Optional
@@ -283,7 +284,7 @@ def compile_(  # noqa: F811
     return s.compile(filename, mode, flags, _genframe=_genframe)
 
 
-def getfslineno(obj) -> Tuple[Optional[Union["Literal['']", py.path.local]], int]:
+def getfslineno(obj: Any) -> Tuple[Union[str, py.path.local], int]:
     """ Return source location (path, lineno) for the given object.
     If the source cannot be determined return ("", -1).
 
@@ -306,18 +307,16 @@ def getfslineno(obj) -> Tuple[Optional[Union["Literal['']", py.path.local]], int
         except TypeError:
             return "", -1
 
-        fspath = fn and py.path.local(fn) or None
+        fspath = fn and py.path.local(fn) or ""
         lineno = -1
         if fspath:
             try:
                 _, lineno = findsource(obj)
             except IOError:
                 pass
+        return fspath, lineno
     else:
-        fspath = code.path
+        return code.path, code.firstlineno
-        lineno = code.firstlineno
-    assert isinstance(lineno, int)
-    return fspath, lineno
 
 
 #

src/_pytest/compat.py

@@ -308,9 +308,9 @@ def get_real_method(obj, holder):
 
 def getfslineno(obj) -> Tuple[Union[str, py.path.local], int]:
     """(**Deprecated**, use _pytest._code.source.getfslineno directly)"""
-    from _pytest._code.source import getfslineno
+    import _pytest._code.source
 
-    return getfslineno(obj)
+    return _pytest._code.source.getfslineno(obj)
 
 
 def getimfunc(func):