Clear the context flags if a context is initialized from the DefaultContext.

Lib/test/test_decimal.py

@@ -56,6 +56,76 @@ sys.modules['decimal'] = C
 fractions = {C:cfractions, P:pfractions}
 sys.modules['decimal'] = orig_sys_decimal
 
+############ RunFirst ############
+class RunFirst(unittest.TestCase):
+
+   def setUp(self):
+       self.save_default = self.decimal.DefaultContext.copy()
+
+   def tearDown(self):
+       DefaultContext = self.decimal.DefaultContext
+
+       DefaultContext.prec = self.save_default.prec
+       DefaultContext.rounding = self.save_default.rounding
+       DefaultContext.Emax = self.save_default.Emax
+       DefaultContext.Emin = self.save_default.Emin
+       DefaultContext.capitals = self.save_default.capitals
+       DefaultContext.clamp = self.save_default.clamp
+       DefaultContext.flags = self.save_default.flags
+       DefaultContext.traps = self.save_default.traps
+
+       self.decimal.setcontext(self.decimal.DefaultContext)
+
+   def test_00default_context(self):
+       # The test depends on the fact that getcontext() is called
+       # for the first time.
+       DefaultContext = self.decimal.DefaultContext
+       ROUND_05UP = self.decimal.ROUND_05UP
+       Clamped = self.decimal.Clamped
+       InvalidOperation = self.decimal.InvalidOperation
+
+       DefaultContext.prec = 5001
+       DefaultContext.rounding = ROUND_05UP
+       DefaultContext.Emax = 10025
+       DefaultContext.Emin = -10025
+       DefaultContext.capitals = 0
+       DefaultContext.clamp = 1
+       DefaultContext.flags[InvalidOperation] = True
+       DefaultContext.clear_traps()
+       DefaultContext.traps[Clamped] = True
+
+       # implicit initialization on first access
+       c = self.decimal.getcontext()
+
+       self.assertEqual(c.prec, 5001)
+       self.assertEqual(c.rounding, ROUND_05UP)
+       self.assertEqual(c.Emax, 10025)
+       self.assertEqual(c.Emin, -10025)
+       self.assertEqual(c.capitals, 0)
+       self.assertEqual(c.clamp, 1)
+       for k in c.flags:
+           self.assertFalse(c.flags[k])
+       for k in c.traps:
+           if k is Clamped:
+               self.assertTrue(c.traps[k])
+           else:
+               self.assertFalse(c.traps[k])
+
+       # explicit initialization
+       self.decimal.setcontext(DefaultContext)
+       c = self.decimal.getcontext()
+       for k in c.flags:
+           self.assertFalse(c.flags[k])
+
+class CRunFirst(RunFirst):
+    decimal = C
+class PyRunFirst(RunFirst):
+    decimal = P
+if C:
+    run_unittest(CRunFirst, PyRunFirst)
+else:
+    run_unittest(PyRunFirst)
+############ END RunFirst ############
 
 # Useful Test Constant
 Signals = {

Modules/_decimal/_decimal.c

@@ -1494,6 +1494,10 @@ current_context(void)
     }
 
     *CTX(module_context) = *CTX(default_context_template);
+    CTX(module_context)->status = 0;
+    CTX(module_context)->newtrap = 0;
+    CtxCaps(module_context) = CtxCaps(default_context_template);
+
     module_context_set = 1;
     return module_context;
 }
@@ -1533,6 +1537,7 @@ PyDec_SetCurrentContext(PyObject *self UNUSED, PyObject *v)
         if (v == NULL) {
             return NULL;
         }
+        CTX(v)->status = 0;
     }
     else {
         Py_INCREF(v);
@@ -1581,6 +1586,8 @@ current_context(void)
     if (tl_context == NULL) {
         return NULL;
     }
+    CTX(tl_context)->status = 0;
+
     if (PyDict_SetItem(dict, tls_context_key, tl_context) < 0) {
         Py_DECREF(tl_context);
         return NULL;
@@ -1646,6 +1653,7 @@ PyDec_SetCurrentContext(PyObject *self UNUSED, PyObject *v)
         if (v == NULL) {
             return NULL;
         }
+        CTX(v)->status = 0;
     }
     else {
         Py_INCREF(v);