Fixed unhelpful error message in from_thread_run functions.

trio/_core/_run.py

@@ -1273,6 +1273,9 @@ async def python_wrapper(orig_coro):
             LOCALS_KEY_KI_PROTECTION_ENABLED, system_task
         )
 
+        ######
+        # Set up the Task object
+        ######
         task = Task._create(
             coro=coro,
             parent_nursery=nursery,

trio/_core/tests/test_run.py

@@ -1698,10 +1698,9 @@ async def main():
         async def f():  # pragma: no cover
             pass
 
-        with ignore_coroutine_never_awaited_warnings():
-            with pytest.raises(TypeError, match="expecting an async function"):
+        with pytest.raises(TypeError, match="expecting an async function"):
 
-                bad_call(f())
+            bad_call(f())
 
         async def async_gen(arg):  # pragma: no cover
             yield arg
@@ -1710,7 +1709,6 @@ async def async_gen(arg):  # pragma: no cover
             TypeError,
             match="expected an async function but got an async generator"
         ):
-
             bad_call(async_gen, 0)
 
 

trio/_threads.py

@@ -411,7 +411,7 @@ def from_thread_run_sync(fn, *args, trio_token=None):
             which would otherwise cause a deadlock.
         AttributeError: if no ``trio_token`` was provided, and we can't infer
             one from context. Also if ``fn`` is not a sync function.
-        TypeError: if ``fn`` is not callable or is an async function.
+        TypeError: if ``fn`` is an async function.
 
     **Locating a Trio Token**: There are two ways to specify which
     `trio.run` loop to reenter:
@@ -427,16 +427,18 @@ def from_thread_run_sync(fn, *args, trio_token=None):
     def callback(q, fn, args):
         @disable_ki_protection
         def unprotected_fn():
-            call = fn(*args)
+            ret = fn(*args)
 
-            if inspect.iscoroutine(call):
-                call.close()
+            if inspect.iscoroutine(ret):
+
+                # Manually close coroutine to avoid RuntimeWarnings
+                ret.close()
                 raise TypeError(
                     "Trio expected a sync function, but {!r} appears to be "
                     "asynchronous".format(getattr(fn, "__qualname__", fn))
                 )
 
-            return call
+            return ret
 
         res = outcome.capture(unprotected_fn)
         q.put_nowait(res)

trio/tests/test_threads.py

@@ -13,7 +13,6 @@
 )
 
 from .._core.tests.test_ki import ki_self
-from .._core.tests.tutil import ignore_coroutine_never_awaited_warnings
 
 
 async def test_do_in_trio_thread():