[Feature] Change cache.py with pydantic validation (#26390)

Signed-off-by: Vinay Damodaran <vrdn@hey.com>
Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>
Co-authored-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

vllm/engine/arg_utils.py

@@ -27,6 +27,7 @@ import huggingface_hub
 import regex as re
 import torch
 from pydantic import TypeAdapter, ValidationError
+from pydantic.fields import FieldInfo
 from typing_extensions import TypeIs, deprecated
 
 import vllm.envs as envs
@@ -209,6 +210,13 @@ def _compute_kwargs(cls: ConfigType) -> dict[str, Any]:
         # Get the default value of the field
         if field.default is not MISSING:
             default = field.default
+            # Handle pydantic.Field defaults
+            if isinstance(default, FieldInfo):
+                default = (
+                    default.default
+                    if default.default_factory is None
+                    else default.default_factory()
+                )
         elif field.default_factory is not MISSING:
             default = field.default_factory()