Remove raise statements from function bodies (#3355)

While it may eventually be useful to mark the exceptions that can be
raised from a function or method, the semantics are currently undefined
and unclear.

stdlib/3/_tracemalloc.pyi

@@ -6,21 +6,11 @@
 from typing import Any, Tuple
 
 def _get_object_traceback(*args, **kwargs) -> Any: ...
-
-def _get_traces() -> Any:
-    raise MemoryError()
-
+def _get_traces() -> Any: ...
 def clear_traces() -> None: ...
-
 def get_traceback_limit() -> int: ...
-
 def get_traced_memory() -> Tuple[Any, ...]: ...
-
 def get_tracemalloc_memory() -> Any: ...
-
 def is_tracing() -> bool: ...
-
-def start(*args, **kwargs) -> None:
-    raise ValueError()
-
+def start(*args, **kwargs) -> None: ...
 def stop() -> None: ...

stdlib/3/collections/__init__.pyi

@@ -220,18 +220,15 @@ class deque(MutableSequence[_T], Generic[_T]):
     @overload
     def __getitem__(self, index: int) -> _T: ...
     @overload
-    def __getitem__(self, s: slice) -> MutableSequence[_T]:
-        raise TypeError
+    def __getitem__(self, s: slice) -> MutableSequence[_T]: ...
     @overload
     def __setitem__(self, i: int, x: _T) -> None: ...
     @overload
-    def __setitem__(self, s: slice, o: Iterable[_T]) -> None:
-        raise TypeError
+    def __setitem__(self, s: slice, o: Iterable[_T]) -> None: ...
     @overload
     def __delitem__(self, i: int) -> None: ...
     @overload
-    def __delitem__(self, s: slice) -> None:
-        raise TypeError
+    def __delitem__(self, s: slice) -> None: ...
 
     def __contains__(self, o: object) -> bool: ...
     def __reversed__(self) -> Iterator[_T]: ...

stdlib/3/signal.pyi

@@ -132,42 +132,17 @@ class struct_siginfo(Tuple[int, int, int, int, int, int, int]):
     def si_band(self) -> int: ...
 
 def alarm(time: int) -> int: ...
-
-def default_int_handler(signum: int, frame: FrameType) -> None:
-    raise KeyboardInterrupt()
-
+def default_int_handler(signum: int, frame: FrameType) -> None: ...
 def getitimer(which: int) -> Tuple[float, float]: ...
-
-def getsignal(signalnum: _SIGNUM) -> _HANDLER:
-    raise ValueError()
-
+def getsignal(signalnum: _SIGNUM) -> _HANDLER: ...
 def pause() -> None: ...
-
-def pthread_kill(thread_id: int, signum: int) -> None:
-    raise OSError()
-
-def pthread_sigmask(how: int, mask: Iterable[int]) -> Set[_SIGNUM]:
-    raise OSError()
-
+def pthread_kill(thread_id: int, signum: int) -> None: ...
+def pthread_sigmask(how: int, mask: Iterable[int]) -> Set[_SIGNUM]: ...
 def set_wakeup_fd(fd: int) -> int: ...
-
 def setitimer(which: int, seconds: float, interval: float = ...) -> Tuple[float, float]: ...
-
-def siginterrupt(signalnum: int, flag: bool) -> None:
-    raise OSError()
-
-def signal(signalnum: _SIGNUM, handler: _HANDLER) -> _HANDLER:
-    raise OSError()
-
-def sigpending() -> Any:
-    raise OSError()
-
-def sigtimedwait(sigset: Iterable[int], timeout: float) -> Optional[struct_siginfo]:
-    raise OSError()
-    raise ValueError()
-
-def sigwait(sigset: Iterable[int]) -> _SIGNUM:
-    raise OSError()
-
-def sigwaitinfo(sigset: Iterable[int]) -> struct_siginfo:
-    raise OSError()
+def siginterrupt(signalnum: int, flag: bool) -> None: ...
+def signal(signalnum: _SIGNUM, handler: _HANDLER) -> _HANDLER: ...
+def sigpending() -> Any: ...
+def sigtimedwait(sigset: Iterable[int], timeout: float) -> Optional[struct_siginfo]: ...
+def sigwait(sigset: Iterable[int]) -> _SIGNUM: ...
+def sigwaitinfo(sigset: Iterable[int]) -> struct_siginfo: ...

stdlib/3/string.pyi

@@ -32,10 +32,7 @@ class Formatter:
     def parse(self, format_string: str) -> Iterable[Tuple[str, Optional[str], Optional[str], Optional[str]]]: ...
     def get_field(self, field_name: str, args: Sequence[Any],
                   kwargs: Mapping[str, Any]) -> Any: ...
-    def get_value(self, key: Union[int, str], args: Sequence[Any],
-                  kwargs: Mapping[str, Any]) -> Any:
-        raise IndexError()
-        raise KeyError()
+    def get_value(self, key: Union[int, str], args: Sequence[Any], kwargs: Mapping[str, Any]) -> Any: ...
     def check_unused_args(self, used_args: Sequence[Union[int, str]], args: Sequence[Any],
                           kwargs: Mapping[str, Any]) -> None: ...
     def format_field(self, value: Any, format_spec: str) -> Any: ...

stdlib/3/sys.pyi

@@ -135,8 +135,7 @@ def excepthook(type_: Type[BaseException], value: BaseException,
                traceback: TracebackType) -> None: ...
 def exc_info() -> _OptExcInfo: ...
 # sys.exit() accepts an optional argument of anything printable
-def exit(arg: object = ...) -> NoReturn:
-    raise SystemExit()
+def exit(arg: object = ...) -> NoReturn: ...
 def getcheckinterval() -> int: ...  # deprecated
 def getdefaultencoding() -> str: ...
 if sys.platform != 'win32':