Add Python 3.13 deprecation warning documentation (#2743)

* Add Python 3.13 deprecation warning documentation

* Address review comments: add code block language and clarify filterwarnings

Author: koxudaxi

docs/cli-reference/typing-customization.md

@@ -664,6 +664,13 @@ The --disable-future-imports option stops the generator from adding
 you need compatibility with tools or environments that don't support
 postponed evaluation of annotations (PEP 563).
 
+**Python 3.13+ Deprecation Warning:** When using `from __future__ import annotations`
+with older versions of Pydantic v1 (before 1.10.18), Python 3.13 may raise
+deprecation warnings related to `typing._eval_type()`. To avoid these warnings:
+
+- Upgrade to Pydantic v1 >= 1.10.18 or Pydantic v2 (recommended)
+- Use this `--disable-future-imports` flag as a workaround
+
 **See also:** [Python Version Compatibility](../python-version-compatibility.md)
 
 !!! tip "Usage"

docs/python-version-compatibility.md

@@ -309,6 +309,44 @@ This can happen when `__future__.annotations` interacts poorly with Pydantic's t
 
 **Solution:** Try `--disable-future-imports` or update to Pydantic v2.
 
+### Python 3.13 DeprecationWarning with `typing._eval_type`
+
+When running on Python 3.13+ with `from __future__ import annotations`, you may see:
+
+```text
+DeprecationWarning: Failing to pass a value to the 'type_params' parameter
+of 'typing._eval_type' is deprecated...
+```
+
+This occurs because Python 3.13 deprecated calling `typing._eval_type()` without the `type_params` parameter. Libraries that evaluate forward references (like older Pydantic versions) trigger this warning.
+
+**Solutions:**
+
+1. **Upgrade Pydantic** (recommended):
+   - Pydantic v1: Upgrade to version 1.10.18 or later
+   - Pydantic v2: Upgrade to the latest version
+
+2. **Use `--disable-future-imports`** as a workaround:
+   ```bash
+   datamodel-codegen --input schema.json --output models.py --disable-future-imports
+   ```
+
+3. **Suppress the warning** in pytest (temporary fix):
+   ```toml
+   # pyproject.toml
+   [tool.pytest.ini_options]
+   filterwarnings = [
+       # For Pydantic v2's v1 compatibility layer (pydantic.v1)
+       "ignore::DeprecationWarning:pydantic.v1.typing",
+       # For standalone Pydantic v1
+       "ignore::DeprecationWarning:pydantic.typing",
+   ]
+   ```
+
+!!! note
+    Python 3.14+ will use native deferred annotations (PEP 649), and the generator
+    will no longer add `from __future__ import annotations` for those versions.
+
 ### IDE shows type errors
 
 Some IDEs don't fully understand `from __future__ import annotations`.

tests/main/jsonschema/test_main_jsonschema.py

@@ -137,6 +137,13 @@ def test_main_keep_model_order_field_references(output_file: Path) -> None:
     'from __future__ import annotations' to the output. This is useful when
     you need compatibility with tools or environments that don't support
     postponed evaluation of annotations (PEP 563).
+
+    **Python 3.13+ Deprecation Warning:** When using `from __future__ import annotations`
+    with older versions of Pydantic v1 (before 1.10.18), Python 3.13 may raise
+    deprecation warnings related to `typing._eval_type()`. To avoid these warnings:
+
+    - Upgrade to Pydantic v1 >= 1.10.18 or Pydantic v2 (recommended)
+    - Use this `--disable-future-imports` flag as a workaround
     """
     run_main_and_assert(
         input_path=JSON_SCHEMA_DATA_PATH / "keep_model_order_field_references.json",