typing: add type hints to pycompat.maplist()

The typeshed hints define 5 overloads with an increasing number of parameters on
the passed function, and then a catchall that ignores the argument list on the
passed function and allows an `*iterators` arg.  All of our uses are fulfilled
by the 1 function + 1 iterable overload, but add the second overload as a hint
in case it's needed in the future.

mercurial/pycompat.py

@@ -32,6 +32,7 b' from typing import ('
     Any,
     AnyStr,
     BinaryIO,
+    Callable,
     Dict,
     Iterable,
     Iterator,
@@ -58,6 +59,8 b' if not globals(): # hide this from non-'
 
 _GetOptResult = Tuple[List[Tuple[bytes, bytes]], List[bytes]]
 _T0 = TypeVar('_T0')
+_T1 = TypeVar('_T1')
+_S = TypeVar('_S')
 _Tbytestr = TypeVar('_Tbytestr', bound='bytestr')
 
 
@@ -129,8 +132,21 b' sysplatform: bytes = sys.platform.encode'
 sysexecutable: bytes = os.fsencode(sys.executable) if sys.executable else b''
 
 
-def maplist(*args):
-    return list(map(*args))
+if TYPE_CHECKING:
+
+    @overload
+    def maplist(f: Callable[[_T0], _S], arg: Iterable[_T0]) -> List[_S]:
+        ...
+
+    @overload
+    def maplist(
+        f: Callable[[_T0, _T1], _S], arg1: Iterable[_T0], arg2: Iterable[_T1]
+    ) -> List[_S]:
+        ...
+
+
+def maplist(f, *args):
+    return list(map(f, *args))
 
 
 def rangelist(*args):