[Code Quality] Add missing return type annotations to core modules

Add return type annotations to functions in:
- vllm/plugins/__init__.py: load_general_plugins() -> None
- vllm/beam_search.py: create_sort_beams_key_function() -> Callable
- vllm/forward_context.py: create_forward_context() -> ForwardContext,
  override_forward_context() and set_forward_context() -> Generator

Signed-off-by: yurekami <yurekami@users.noreply.github.com>

vllm/beam_search.py

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
+from collections.abc import Callable
 from dataclasses import dataclass
 from typing import TYPE_CHECKING, Any, Optional
 
@@ -79,7 +80,9 @@ def get_beam_search_score(
     return cumulative_logprob / (seq_len**length_penalty)
 
 
-def create_sort_beams_key_function(eos_token_id: int, length_penalty: float):
+def create_sort_beams_key_function(
+    eos_token_id: int, length_penalty: float
+) -> Callable[[BeamSearchSequence], float]:
     def sort_beams_key(x: BeamSearchSequence) -> float:
         return get_beam_search_score(
             x.tokens, x.cum_logprob, eos_token_id, length_penalty

vllm/forward_context.py

@@ -3,6 +3,7 @@
 
 import time
 from collections import defaultdict
+from collections.abc import Generator
 from contextlib import contextmanager
 from dataclasses import dataclass
 from typing import Any, NamedTuple
@@ -235,7 +236,7 @@ def create_forward_context(
     cudagraph_runtime_mode: CUDAGraphMode = CUDAGraphMode.NONE,
     batch_descriptor: BatchDescriptor | None = None,
     ubatch_slices: UBatchSlices | None = None,
-):
+) -> ForwardContext:
     return ForwardContext(
         no_compile_layers=vllm_config.compilation_config.static_forward_context,
         virtual_engine=virtual_engine,
@@ -248,7 +249,9 @@ def create_forward_context(
 
 
 @contextmanager
-def override_forward_context(forward_context: ForwardContext | None):
+def override_forward_context(
+    forward_context: ForwardContext | None,
+) -> Generator[None, None, None]:
     """A context manager that overrides the current forward context.
     This is used to override the forward context for a specific
     forward pass.
@@ -272,7 +275,7 @@ def set_forward_context(
     cudagraph_runtime_mode: CUDAGraphMode = CUDAGraphMode.NONE,
     batch_descriptor: BatchDescriptor | None = None,
     ubatch_slices: UBatchSlices | None = None,
-):
+) -> Generator[None, None, None]:
     """A context manager that stores the current forward context,
     can be attention metadata, etc.
     Here we can inject common logic for every model forward pass.

vllm/plugins/__init__.py

@@ -65,7 +65,7 @@ def load_plugins_by_group(group: str) -> dict[str, Callable[[], Any]]:
     return plugins
 
 
-def load_general_plugins():
+def load_general_plugins() -> None:
     """WARNING: plugins can be loaded for multiple times in different
     processes. They should be designed in a way that they can be loaded
     multiple times without causing issues.