[3.15] gh-153068: Preserve cprofile enable errors (GH-153070) (#153241)

Author: miss-islington

Lib/test/test_profiling/test_tracing_profiler.py

@@ -117,8 +117,9 @@ def test_second_profiler(self):
         pr = self.profilerclass()
         pr2 = self.profilerclass()
         pr.enable()
-        self.assertRaises(ValueError, pr2.enable)
-        pr.disable()
+        self.addCleanup(pr.disable)
+        msg = f"tool {sys.monitoring.PROFILER_ID} is already in use"
+        self.assertRaisesRegex(ValueError, msg, pr2.enable)
 
     def test_throw(self):
         """

Misc/NEWS.d/next/Library/2026-07-05-16-09-31.gh-issue-153068.huY9Jh.rst

@@ -0,0 +1,2 @@
+Fix :meth:`!cProfile.Profile.enable` to no longer overwrite errors from
+:mod:`sys.monitoring`.

Modules/_lsprof.c

@@ -821,7 +821,6 @@ _lsprof_Profiler_enable_impl(ProfilerObject *self, int subcalls,
                                           "use_tool_id", "is",
                                           self->tool_id, "cProfile");
     if (check == NULL) {
-        PyErr_Format(PyExc_ValueError, "Another profiling tool is already active");
         goto error;
     }
     Py_DECREF(check);