fix(tracing): ensure tracer.wrap preserves decorated function’s type (#13906)

This change reverts a regression introduced in
`@tracer.wrap()` causes type checkers to infer the return type of
decorated functions as `Any` instead of the actual return type.

Addresses #13637

- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

- [x] Reviewer has checked that all the criteria below are met
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
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[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

---------

Co-authored-by: Joseph Zemek <jazemek@gmail.com>
Co-authored-by: Rachel Yang <rachel.yang@datadoghq.com>
Co-authored-by: Brett Langdon <brett.langdon@datadoghq.com>

Author: 3 people

ddtrace/_trace/tracer.py

@@ -8,13 +8,14 @@
 from os import getpid
 from threading import RLock
 from typing import TYPE_CHECKING
-from typing import Any
 from typing import Callable
 from typing import Dict
 from typing import List
 from typing import Optional
 from typing import Tuple
+from typing import TypeVar
 from typing import Union
+from typing import cast
 
 from ddtrace._hooks import Hooks
 from ddtrace._trace.context import Context
@@ -66,7 +67,7 @@
 log = get_logger(__name__)
 
 
-AnyCallable = Callable[..., Any]
+AnyCallable = TypeVar("AnyCallable", bound=Callable)
 
 if TYPE_CHECKING:
     from ddtrace.appsec._processor import AppSecSpanProcessor
@@ -779,7 +780,7 @@ def func_wrapper(*args, **kwargs):
                 return_value = yield from f(*args, **kwargs)
                 return return_value
 
-        return func_wrapper
+        return cast(AnyCallable, func_wrapper)
 
     def _wrap_generator_async(
         self,
@@ -797,7 +798,7 @@ async def func_wrapper(*args, **kwargs):
                 async for value in f(*args, **kwargs):
                     yield value
 
-        return func_wrapper
+        return cast(AnyCallable, func_wrapper)
 
     def wrap(
         self,

releasenotes/notes/fix-tracer-wrap-return-type-c9436d6861451dab.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    tracing: This fix resolves an issue where the ``@tracer.wrap()`` decorator failed to preserve the decorated function's return type, returning ``Any`` instead of the original return type.