bpo-32089: Fix warnings filters in dev mode (#4482)

The developer mode (-X dev) now creates all default warnings filters
to order filters in the correct order to always show ResourceWarning
and make BytesWarning depend on the -b option.

Write a functional test to make sure that ResourceWarning is logged
twice at the same location in the developer mode.

Add a new 'dev_mode' field to _PyCoreConfig.

1 files changed, 27 insertions, 10 deletions

diff --git a/Python/_warnings.c b/Python/_warnings.c
index 8cfae76..f2110ed 100644
--- a/Python/_warnings.c
+++ b/Python/_warnings.c
@@ -1196,11 +1196,19 @@ create_filter(PyObject *category, const char *action)
 static PyObject *
 init_filters(void)
 {
+    PyInterpreterState *interp = PyThreadState_GET()->interp;
+    int dev_mode = interp->core_config.dev_mode;
+
+    Py_ssize_t count = 2;
+    if (dev_mode) {
+        count++;
+    }
 #ifndef Py_DEBUG
-    PyObject *filters = PyList_New(5);
-#else
-    PyObject *filters = PyList_New(2);
+    if (!dev_mode) {
+        count += 3;
+    }
 #endif
+    PyObject *filters = PyList_New(count);
     unsigned int pos = 0;  /* Post-incremented in each use. */
     unsigned int x;
     const char *bytes_action, *resource_action;
@@ -1209,12 +1217,14 @@ init_filters(void)
         return NULL;
 
 #ifndef Py_DEBUG
-    PyList_SET_ITEM(filters, pos++,
-                    create_filter(PyExc_DeprecationWarning, "ignore"));
-    PyList_SET_ITEM(filters, pos++,
-                    create_filter(PyExc_PendingDeprecationWarning, "ignore"));
-    PyList_SET_ITEM(filters, pos++,
-                    create_filter(PyExc_ImportWarning, "ignore"));
+    if (!dev_mode) {
+        PyList_SET_ITEM(filters, pos++,
+                        create_filter(PyExc_DeprecationWarning, "ignore"));
+        PyList_SET_ITEM(filters, pos++,
+                        create_filter(PyExc_PendingDeprecationWarning, "ignore"));
+        PyList_SET_ITEM(filters, pos++,
+                        create_filter(PyExc_ImportWarning, "ignore"));
+    }
 #endif
 
     if (Py_BytesWarningFlag > 1)
@@ -1225,14 +1235,21 @@ init_filters(void)
         bytes_action = "ignore";
     PyList_SET_ITEM(filters, pos++, create_filter(PyExc_BytesWarning,
                     bytes_action));
+
     /* resource usage warnings are enabled by default in pydebug mode */
 #ifdef Py_DEBUG
     resource_action = "always";
 #else
-    resource_action = "ignore";
+    resource_action = (dev_mode ? "always" : "ignore");
 #endif
     PyList_SET_ITEM(filters, pos++, create_filter(PyExc_ResourceWarning,
                     resource_action));
+
+    if (dev_mode) {
+        PyList_SET_ITEM(filters, pos++,
+                        create_filter(PyExc_Warning, "default"));
+    }
+
     for (x = 0; x < pos; x += 1) {
         if (PyList_GET_ITEM(filters, x) == NULL) {
             Py_DECREF(filters);