Merged revisions 62260-62261,62266,62271,62277-62279,62289-62290,62293-62298,62302-62306,62308,62311,62313-62315,62319-62321 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r62260 | gregory.p.smith | 2008-04-10 01:11:56 +0200 (Thu, 10 Apr 2008) | 2 lines

  better diagnostics
........
  r62261 | gregory.p.smith | 2008-04-10 01:16:37 +0200 (Thu, 10 Apr 2008) | 3 lines

  Raise SystemError when size < 0 is passed into PyString_FromStringAndSize,
  PyBytes_FromStringAndSize or PyUnicode_FromStringAndSize.  [issue2587]
........
  r62266 | neal.norwitz | 2008-04-10 07:46:39 +0200 (Thu, 10 Apr 2008) | 5 lines

  Remove the test file before writing it in case there is no write permission.
  This might help fix some of the failures on Windows box(es).  It doesn't hurt
  either way and ensure the tests are a little more self contained (ie have
  less assumptions).
........
  r62271 | gregory.p.smith | 2008-04-10 21:50:36 +0200 (Thu, 10 Apr 2008) | 2 lines

  get rid of assert (size >= 0) now that an explicit if (size < 0) is in the code.
........
  r62277 | andrew.kuchling | 2008-04-10 23:27:10 +0200 (Thu, 10 Apr 2008) | 1 line

  Remove forward-looking statement
........
  r62278 | andrew.kuchling | 2008-04-10 23:28:51 +0200 (Thu, 10 Apr 2008) | 1 line

  Add punctuation
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  r62279 | andrew.kuchling | 2008-04-10 23:29:01 +0200 (Thu, 10 Apr 2008) | 1 line

  Use issue directive
........
  r62289 | thomas.heller | 2008-04-11 15:05:38 +0200 (Fri, 11 Apr 2008) | 3 lines

  Move backwards compatibility macro to the correct place;
  PyIndex_Check() was introduced in Python 2.5.
........
  r62290 | thomas.heller | 2008-04-11 16:20:26 +0200 (Fri, 11 Apr 2008) | 2 lines

  Performance improvements.
........
  r62293 | christian.heimes | 2008-04-12 15:03:03 +0200 (Sat, 12 Apr 2008) | 2 lines

  Applied patch #2617 from Frank Wierzbicki wit some extras from me
  -J and -X are now reserved for Jython and non-standard arguments (e.g. IronPython). I've added some extra comments to make sure the reservation don't get missed in the future.
........
  r62294 | georg.brandl | 2008-04-12 20:11:18 +0200 (Sat, 12 Apr 2008) | 2 lines

  Use absolute path in sys.path.
........
  r62295 | georg.brandl | 2008-04-12 20:36:09 +0200 (Sat, 12 Apr 2008) | 2 lines

  #2615: small consistency update by Jeroen Ruigrok van der Werven.
........
  r62296 | georg.brandl | 2008-04-12 21:00:20 +0200 (Sat, 12 Apr 2008) | 2 lines

  Add Jeroen.
........
  r62297 | georg.brandl | 2008-04-12 21:05:37 +0200 (Sat, 12 Apr 2008) | 2 lines

  Don't offend snake lovers.
........
  r62298 | gregory.p.smith | 2008-04-12 22:37:48 +0200 (Sat, 12 Apr 2008) | 2 lines

  fix compiler warnings
........
  r62302 | gregory.p.smith | 2008-04-13 00:24:04 +0200 (Sun, 13 Apr 2008) | 3 lines

  socket.error inherits from IOError, it no longer needs listing in
  the all_errors tuple.
........
  r62303 | brett.cannon | 2008-04-13 01:44:07 +0200 (Sun, 13 Apr 2008) | 8 lines

  Re-implement the 'warnings' module in C. This allows for usage of the
  'warnings' code in places where it was previously not possible (e.g., the
  parser). It could also potentially lead to a speed-up in interpreter start-up
  if the C version of the code (_warnings) is imported over the use of the
  Python version in key places.

  Closes issue #1631171.
........
  r62304 | gregory.p.smith | 2008-04-13 02:03:25 +0200 (Sun, 13 Apr 2008) | 3 lines

  Adds a profile-opt target for easy compilation of a python binary using
  gcc's profile guided optimization.
........
  r62305 | brett.cannon | 2008-04-13 02:18:44 +0200 (Sun, 13 Apr 2008) | 3 lines

  Fix a bug in PySys_HasWarnOption() where it was not properly checking the
  length of the list storing the warning options.
........
  r62306 | brett.cannon | 2008-04-13 02:25:15 +0200 (Sun, 13 Apr 2008) | 2 lines

  Fix an accidental bug of an non-existent init function.
........
  r62308 | andrew.kuchling | 2008-04-13 03:05:59 +0200 (Sun, 13 Apr 2008) | 1 line

  Mention -J, -X
........
  r62311 | benjamin.peterson | 2008-04-13 04:20:05 +0200 (Sun, 13 Apr 2008) | 2 lines

  Give the "Interactive Interpreter Changes" section in 2.6 whatsnew a unique link name
........
  r62313 | brett.cannon | 2008-04-13 04:42:36 +0200 (Sun, 13 Apr 2008) | 3 lines

  Fix test_warnings by making the state of things more consistent for each test
  when it is run.
........
  r62314 | skip.montanaro | 2008-04-13 05:17:30 +0200 (Sun, 13 Apr 2008) | 2 lines

  spelling
........
  r62315 | georg.brandl | 2008-04-13 09:07:44 +0200 (Sun, 13 Apr 2008) | 2 lines

  Fix markup.
........
  r62319 | christian.heimes | 2008-04-13 11:30:17 +0200 (Sun, 13 Apr 2008) | 1 line

  Fix compiler warning Include/warnings.h:19:28: warning: no newline at end of file
........
  r62320 | christian.heimes | 2008-04-13 11:33:24 +0200 (Sun, 13 Apr 2008) | 1 line

  Use PyString_InternFromString instead of PyString_FromString for static vars
........
  r62321 | christian.heimes | 2008-04-13 11:37:05 +0200 (Sun, 13 Apr 2008) | 1 line

  Added new files to the pcbuild files
........

1 files changed, 856 insertions, 0 deletions

diff --git a/Python/_warnings.c b/Python/_warnings.c
new file mode 100644
index 00000000000..7472ab68c86
--- /dev/null
+++ b/Python/_warnings.c
@@ -0,0 +1,856 @@
+#include "Python.h"
+#include "frameobject.h"
+
+#define MODULE_NAME "_warnings"
+#define DEFAULT_ACTION_NAME "default_action"
+
+PyDoc_STRVAR(warnings__doc__,
+MODULE_NAME " provides basic warning filtering support.\n"
+"It is a helper module to speed up interpreter start-up.");
+
+/* Both 'filters' and 'onceregistry' can be set in warnings.py;
+   get_warnings_attr() will reset these variables accordingly. */
+static PyObject *_filters;  /* List */
+static PyObject *_once_registry;  /* Dict */
+
+
+static int
+check_matched(PyObject *obj, PyObject *arg)
+{
+    PyObject *result;
+    int rc;
+
+    if (obj == Py_None)
+        return 1;
+    result = PyObject_CallMethod(obj, "match", "O", arg);
+    if (result == NULL)
+        return -1;
+
+    rc = PyObject_IsTrue(result);
+    Py_DECREF(result);
+    return rc;
+}
+
+/*
+   Returns a new reference.
+   A NULL return value can mean false or an error.
+*/
+static PyObject *
+get_warnings_attr(const char *attr)
+{
+    static PyObject *warnings_str = NULL;
+    PyObject *all_modules;
+    PyObject *warnings_module;
+    int result;
+
+    if (warnings_str == NULL) {
+        warnings_str = PyUnicode_InternFromString("warnings");
+        if (warnings_str == NULL)
+            return NULL;
+    }
+
+    all_modules = PyImport_GetModuleDict();
+    result = PyDict_Contains(all_modules, warnings_str);
+    if (result == -1 || result == 0)
+        return NULL;
+
+    warnings_module = PyDict_GetItem(all_modules, warnings_str);
+    if (!PyObject_HasAttrString(warnings_module, attr))
+            return NULL;
+    return PyObject_GetAttrString(warnings_module, attr);
+}
+
+
+PyObject *
+get_once_registry(void)
+{
+    PyObject *registry;
+
+    registry = get_warnings_attr("onceregistry");
+    if (registry == NULL) {
+        if (PyErr_Occurred())
+            return NULL;
+        return _once_registry;
+    }
+    Py_DECREF(_once_registry);
+    _once_registry = registry;
+    return registry;
+}
+
+
+/* The item is a borrowed reference. */
+static const char *
+get_filter(PyObject *category, PyObject *text, Py_ssize_t lineno,
+           PyObject *module, PyObject **item)
+{
+    PyObject *action, *m, *d;
+    Py_ssize_t i;
+    PyObject *warnings_filters;
+
+    warnings_filters = get_warnings_attr("filters");
+    if (warnings_filters == NULL) {
+        if (PyErr_Occurred())
+            return NULL;
+    }
+    else {
+        Py_DECREF(_filters);
+        _filters = warnings_filters;
+    }
+
+    if (!PyList_Check(_filters)) {
+        PyErr_SetString(PyExc_ValueError,
+                        MODULE_NAME ".filters must be a list");
+        return NULL;
+    }
+
+    /* _filters could change while we are iterating over it. */
+    for (i = 0; i < PyList_GET_SIZE(_filters); i++) {
+        PyObject *tmp_item, *action, *msg, *cat, *mod, *ln_obj;
+        Py_ssize_t ln;
+        int is_subclass, good_msg, good_mod;
+
+        tmp_item = *item = PyList_GET_ITEM(_filters, i);
+        if (PyTuple_Size(tmp_item) != 5) {
+            PyErr_Format(PyExc_ValueError,
+                         MODULE_NAME ".filters item %zd isn't a 5-tuple", i);
+            return NULL;
+        }
+
+        /* Python code: action, msg, cat, mod, ln = item */
+        action = PyTuple_GET_ITEM(tmp_item, 0);
+        msg = PyTuple_GET_ITEM(tmp_item, 1);
+        cat = PyTuple_GET_ITEM(tmp_item, 2);
+        mod = PyTuple_GET_ITEM(tmp_item, 3);
+        ln_obj = PyTuple_GET_ITEM(tmp_item, 4);
+
+        good_msg = check_matched(msg, text);
+        good_mod = check_matched(mod, module);
+        is_subclass = PyObject_IsSubclass(category, cat);
+        ln = PyLong_AsSsize_t(ln_obj);
+        if (good_msg == -1 || good_mod == -1 || is_subclass == -1 ||
+            (ln == -1 && PyErr_Occurred()))
+            return NULL;
+
+        if (good_msg && is_subclass && good_mod && (ln == 0 || lineno == ln))
+            return PyUnicode_AsString(action);
+    }
+
+    m = PyImport_ImportModule(MODULE_NAME);
+    if (m == NULL)
+        return NULL;
+    d = PyModule_GetDict(m);
+    Py_DECREF(m);
+    if (d == NULL)
+        return NULL;
+    action = PyDict_GetItemString(d, DEFAULT_ACTION_NAME);
+    if (action != NULL)
+        return PyUnicode_AsString(action);
+
+    PyErr_SetString(PyExc_ValueError,
+                    MODULE_NAME "." DEFAULT_ACTION_NAME " not found");
+    return NULL;
+}
+
+static int
+already_warned(PyObject *registry, PyObject *key, int should_set)
+{
+    PyObject *already_warned;
+
+    if (key == NULL)
+        return -1;
+
+    already_warned = PyDict_GetItem(registry, key);
+    if (already_warned != NULL) {
+        int rc = PyObject_IsTrue(already_warned);
+        if (rc != 0)
+            return rc;
+    }
+
+    /* This warning wasn't found in the registry, set it. */
+    if (should_set)
+        return PyDict_SetItem(registry, key, Py_True);
+    return 0;
+}
+
+/* New reference. */
+static PyObject *
+normalize_module(PyObject *filename)
+{
+    PyObject *module;
+    const char *mod_str;
+    Py_ssize_t len;
+
+    int rc = PyObject_IsTrue(filename);
+    if (rc == -1)
+        return NULL;
+    else if (rc == 0)
+        return PyUnicode_FromString("<unknown>");
+
+    mod_str = PyUnicode_AsString(filename);
+    if (mod_str == NULL)
+	    return NULL;
+    len = PyUnicode_GetSize(filename);
+    if (len < 0)
+        return NULL;
+    if (len >= 3 &&
+	strncmp(mod_str + (len - 3), ".py", 3) == 0) {
+        module = PyUnicode_FromStringAndSize(mod_str, len-3);
+    }
+    else {
+        module = filename;
+        Py_INCREF(module);
+    }
+    return module;
+}
+
+static int
+update_registry(PyObject *registry, PyObject *text, PyObject *category,
+                int add_zero)
+{
+    PyObject *altkey, *zero = NULL;
+    int rc;
+
+    if (add_zero) {
+        zero = PyLong_FromLong(0);
+        if (zero == NULL)
+            return -1;
+        altkey = PyTuple_Pack(3, text, category, zero);
+    }
+    else
+        altkey = PyTuple_Pack(2, text, category);
+
+    rc = already_warned(registry, altkey, 1);
+    Py_XDECREF(zero);
+    Py_XDECREF(altkey);
+    return rc;
+}
+
+static void
+show_warning(PyObject *filename, int lineno, PyObject *text, PyObject
+                *category, PyObject *sourceline)
+{
+    PyObject *f_stderr; 
+    PyObject *name; 
+    char lineno_str[128];
+
+    PyOS_snprintf(lineno_str, sizeof(lineno_str), ":%d: ", lineno);
+
+    name = PyObject_GetAttrString(category, "__name__");
+    if (name == NULL)  /* XXX Can an object lack a '__name__' attribute? */
+	    return;
+
+    f_stderr = PySys_GetObject("stderr");
+    if (f_stderr == NULL) {
+        fprintf(stderr, "lost sys.stderr\n");
+        Py_DECREF(name);
+        return;
+    }
+
+    /* Print "filename:lineno: category: text\n" */
+    PyFile_WriteObject(filename, f_stderr, Py_PRINT_RAW);
+    PyFile_WriteString(lineno_str, f_stderr);
+    PyFile_WriteObject(name, f_stderr, Py_PRINT_RAW);
+    PyFile_WriteString(": ", f_stderr);
+    PyFile_WriteObject(text, f_stderr, Py_PRINT_RAW);
+    PyFile_WriteString("\n", f_stderr);
+    Py_XDECREF(name);
+
+    /* Print "  source_line\n" */
+    PyFile_WriteString("  ", f_stderr);
+    if (sourceline) {
+        char *source_line_str = PyUnicode_AsString(sourceline);
+        while (*source_line_str == ' ' || *source_line_str == '\t' ||
+                *source_line_str == '\014')
+            source_line_str++;
+
+        PyFile_WriteString(source_line_str, f_stderr);
+        PyFile_WriteString("\n", f_stderr);
+    }
+    else
+        Py_DisplaySourceLine(f_stderr, PyUnicode_AsString(filename), lineno);
+    PyErr_Clear();
+}
+
+static PyObject *
+warn_explicit(PyObject *category, PyObject *message, 
+              PyObject *filename, int lineno,
+              PyObject *module, PyObject *registry, PyObject *sourceline)
+{
+    PyObject *key = NULL, *text = NULL, *result = NULL, *lineno_obj = NULL;
+    PyObject *item = Py_None;
+    const char *action;
+    int rc;
+
+    /* Normalize module. */
+    if (module == NULL) {
+        module = normalize_module(filename);
+        if (module == NULL)
+            return NULL;
+    }
+    else
+        Py_INCREF(module);
+
+    /* Normalize message. */
+    Py_INCREF(message);  /* DECREF'ed in cleanup. */
+    rc = PyObject_IsInstance(message, PyExc_Warning);
+    if (rc == -1) {
+        goto cleanup;
+    }
+    if (rc == 1) {
+        text = PyObject_Str(message);
+        category = (PyObject*)message->ob_type;
+    }
+    else {
+        text = message;
+        message = PyObject_CallFunction(category, "O", message);
+    }
+
+    lineno_obj = PyLong_FromLong(lineno);
+    if (lineno_obj == NULL)
+        goto cleanup;
+
+    /* Create key. */
+    key = PyTuple_Pack(3, text, category, lineno_obj);
+    if (key == NULL)
+        goto cleanup;
+
+    if (registry != NULL) {
+        rc = already_warned(registry, key, 0);
+        if (rc == -1)
+            goto cleanup;
+	else if (rc == 1)
+            goto return_none;
+        /* Else this warning hasn't been generated before. */
+    }
+
+    action = get_filter(category, text, lineno, module, &item);
+    if (action == NULL)
+        goto cleanup;
+
+    if (strcmp(action, "error") == 0) {
+        PyErr_SetObject(category, message);
+        goto cleanup;
+    }
+
+    /* Store in the registry that we've been here, *except* when the action
+       is "always". */
+    rc = 0;
+    if (strcmp(action, "always") != 0) {
+        if (registry != NULL && PyDict_SetItem(registry, key, Py_True) < 0)
+            goto cleanup;
+        else if (strcmp(action, "ignore") == 0)
+            goto return_none;
+        else if (strcmp(action, "once") == 0) {
+            if (registry == NULL) {
+                registry = get_once_registry();
+                if (registry == NULL)
+                    goto cleanup;
+            }
+            /* _once_registry[(text, category)] = 1 */
+            rc = update_registry(registry, text, category, 0); 
+        }
+        else if (strcmp(action, "module") == 0) {
+            /* registry[(text, category, 0)] = 1 */
+            if (registry != NULL)
+                rc = update_registry(registry, text, category, 0); 
+        }
+        else if (strcmp(action, "default") != 0) {
+            PyObject *to_str = PyObject_Str(item);
+            const char *err_str = "???";
+
+            if (to_str != NULL)
+                err_str = PyUnicode_AsString(to_str);
+            PyErr_Format(PyExc_RuntimeError,
+                        "Unrecognized action (%s) in warnings.filters:\n %s",
+                        action, err_str);
+            Py_XDECREF(to_str);
+            goto cleanup;
+        }
+    }
+
+    if (rc == 1)  // Already warned for this module. */
+        goto return_none;
+    if (rc == 0) {
+        PyObject *show_fxn = get_warnings_attr("showwarning");
+        if (show_fxn == NULL) {
+            if (PyErr_Occurred())
+                goto cleanup;
+            show_warning(filename, lineno, text, category, sourceline);
+        }
+        else {
+            PyObject *result;
+            
+            result = PyObject_CallFunctionObjArgs(show_fxn, message, category,
+                                                    filename, lineno_obj,
+                                                    Py_None,
+                                                    sourceline ?
+                                                        sourceline: Py_None,
+                                                    NULL);
+            Py_XDECREF(result);
+            if (result == NULL)
+                goto cleanup;
+        }
+    }
+    else /* if (rc == -1) */
+        goto cleanup;
+
+ return_none:
+    result = Py_None;
+    Py_INCREF(result);
+
+ cleanup:
+    Py_XDECREF(key);
+    Py_XDECREF(text);
+    Py_XDECREF(lineno_obj);
+    Py_DECREF(module);
+    Py_DECREF(message);
+    return result;  /* Py_None or NULL. */
+}
+
+/* filename, module, and registry are new refs, globals is borrowed */
+/* Returns 0 on error (no new refs), 1 on success */
+static int
+setup_context(Py_ssize_t stack_level, PyObject **filename, int *lineno,
+              PyObject **module, PyObject **registry)
+{
+    PyObject *globals;
+
+    /* Setup globals and lineno. */
+    PyFrameObject *f = PyThreadState_GET()->frame;
+    while (--stack_level > 0 && f != NULL) {
+        f = f->f_back;
+        --stack_level;
+    }
+
+    if (f == NULL) {
+        globals = PyThreadState_Get()->interp->sysdict;
+        *lineno = 1;
+    }
+    else {
+        globals = f->f_globals;
+        *lineno = PyCode_Addr2Line(f->f_code, f->f_lasti);
+    }
+
+    *module = NULL;
+
+    /* Setup registry. */
+    assert(globals != NULL);
+    assert(PyDict_Check(globals));
+    *registry = PyDict_GetItemString(globals, "__warningregistry__");
+    if (*registry == NULL) {
+        int rc;
+
+        *registry = PyDict_New();
+        if (*registry == NULL)
+            return 0;
+
+         rc = PyDict_SetItemString(globals, "__warningregistry__", *registry);
+         if (rc < 0)
+            goto handle_error;
+    }
+    else
+        Py_INCREF(*registry);
+
+    /* Setup module. */
+    *module = PyDict_GetItemString(globals, "__name__");
+    if (*module == NULL) {
+        *module = PyUnicode_FromString("<string>");
+        if (*module == NULL)
+            goto handle_error;
+    }
+    else
+        Py_INCREF(*module);
+
+    /* Setup filename. */
+    *filename = PyDict_GetItemString(globals, "__file__");
+    if (*filename != NULL) {
+	Py_ssize_t len = PyUnicode_GetSize(*filename);
+        const char *file_str = PyUnicode_AsString(*filename);
+	if (file_str == NULL || (len < 0 && PyErr_Occurred()))
+            goto handle_error;
+
+        /* if filename.lower().endswith((".pyc", ".pyo")): */
+        if (len >= 4 &&
+            file_str[len-4] == '.' &&
+            tolower(file_str[len-3]) == 'p' &&
+            tolower(file_str[len-2]) == 'y' &&
+            (tolower(file_str[len-1]) == 'c' ||
+             tolower(file_str[len-1]) == 'o')) {
+            *filename = PyUnicode_FromStringAndSize(file_str, len-1);
+	    if (*filename == NULL)
+		    goto handle_error;
+	}
+	else
+            Py_INCREF(*filename);
+    }
+    else {
+        const char *module_str = PyUnicode_AsString(*module);
+        if (module_str && strcmp(module_str, "__main__") == 0) {
+            PyObject *argv = PySys_GetObject("argv");
+            if (argv != NULL && PyList_Size(argv) > 0) {
+                *filename = PyList_GetItem(argv, 0);
+                Py_INCREF(*filename);
+            }
+            else {
+                /* embedded interpreters don't have sys.argv, see bug #839151 */
+                *filename = PyUnicode_FromString("__main__");
+	        if (*filename == NULL)
+	            goto handle_error;
+            }
+        }
+        if (*filename == NULL) {
+            *filename = *module;
+            Py_INCREF(*filename);
+        }
+    }
+
+    return 1;
+
+ handle_error:
+    /* filename not XDECREF'ed here as there is no way to jump here with a
+       dangling reference. */
+    Py_XDECREF(*registry);
+    Py_XDECREF(*module);
+    return 0;
+}
+
+static PyObject *
+get_category(PyObject *message, PyObject *category)
+{
+    int rc;
+
+    /* Get category. */
+    rc = PyObject_IsInstance(message, PyExc_Warning);
+    if (rc == -1)
+        return NULL;
+
+    if (rc == 1)
+        category = (PyObject*)message->ob_type;
+    else if (category == NULL)
+        category = PyExc_UserWarning;
+
+    /* Validate category. */
+    rc = PyObject_IsSubclass(category, PyExc_Warning);
+    if (rc == -1)
+        return NULL;
+    if (rc == 0) {
+        PyErr_SetString(PyExc_ValueError,
+                        "category is not a subclass of Warning");
+        return NULL;
+    }
+
+    return category;
+}
+
+static PyObject *
+do_warn(PyObject *message, PyObject *category, Py_ssize_t stack_level)
+{
+    PyObject *filename, *module, *registry, *res;
+    int lineno;
+
+    if (!setup_context(stack_level, &filename, &lineno, &module, &registry))
+        return NULL;
+
+    res = warn_explicit(category, message, filename, lineno, module, registry,
+                        NULL);
+    Py_DECREF(filename);
+    Py_DECREF(registry);
+    Py_DECREF(module);
+    return res;
+}
+
+static PyObject *
+warnings_warn(PyObject *self, PyObject *args, PyObject *kwds)
+{
+    static char *kw_list[] = { "message", "category", "stacklevel", 0 };
+    PyObject *message, *category = NULL;
+    Py_ssize_t stack_level = 1;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|On:warn", kw_list, 
+                                     &message, &category, &stack_level))
+        return NULL;
+
+    category = get_category(message, category);
+    if (category == NULL)
+        return NULL;
+    return do_warn(message, category, stack_level);
+}
+
+static PyObject *
+warnings_warn_explicit(PyObject *self, PyObject *args, PyObject *kwds)
+{
+    static char *kwd_list[] = {"message", "category", "filename", "lineno",
+                                "module", "registry", "module_globals", 0};
+    PyObject *message;
+    PyObject *category;
+    PyObject *filename;
+    int lineno;
+    PyObject *module = NULL;
+    PyObject *registry = NULL;
+    PyObject *module_globals = NULL;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "OOOi|OOO:warn_explicit",
+                kwd_list, &message, &category, &filename, &lineno, &module,
+                &registry, &module_globals))
+        return NULL;
+
+    if (module_globals) {
+        static PyObject *get_source_name = NULL;
+        static PyObject *splitlines_name = NULL;
+        PyObject *loader;
+        PyObject *module_name;
+        PyObject *source;
+        PyObject *source_list;
+        PyObject *source_line;
+        PyObject *returned;
+
+        if (get_source_name == NULL) {
+            get_source_name = PyUnicode_InternFromString("get_source");
+            if (!get_source_name)
+                return NULL;
+        }
+        if (splitlines_name == NULL) {
+            splitlines_name = PyUnicode_InternFromString("splitlines");
+            if (!splitlines_name)
+                return NULL;
+        }
+
+        /* Check/get the requisite pieces needed for the loader. */
+        loader = PyDict_GetItemString(module_globals, "__loader__");
+        module_name = PyDict_GetItemString(module_globals, "__name__");
+
+        if (loader == NULL || module_name == NULL)
+            goto standard_call;
+
+        /* Make sure the loader implements the optional get_source() method. */
+        if (!PyObject_HasAttrString(loader, "get_source"))
+                goto standard_call;
+        /* Call get_source() to get the source code. */
+        source = PyObject_CallMethodObjArgs(loader, get_source_name,
+                                                module_name, NULL);
+        if (!source)
+            return NULL;
+        else if (source == Py_None) {
+            Py_DECREF(Py_None);
+            goto standard_call;
+        }
+
+        /* Split the source into lines. */
+        source_list = PyObject_CallMethodObjArgs(source, splitlines_name,
+                                                    NULL);
+        Py_DECREF(source);
+        if (!source_list)
+            return NULL;
+
+        /* Get the source line. */
+        source_line = PyList_GetItem(source_list, lineno-1);
+        if (!source_line) {
+            Py_DECREF(source_list);
+            return NULL;
+        }
+
+        /* Handle the warning. */
+        returned = warn_explicit(category, message, filename, lineno, module,
+                            registry, source_line);
+        Py_DECREF(source_list);
+        return returned;
+    }
+
+ standard_call:
+    return warn_explicit(category, message, filename, lineno, module,
+                                registry, NULL);
+}
+
+
+/* Function to issue a warning message; may raise an exception. */
+int
+PyErr_WarnEx(PyObject *category, const char *text, Py_ssize_t stack_level)
+{
+    PyObject *res;
+    PyObject *message = PyUnicode_FromString(text);
+    if (message == NULL)
+        return -1;
+
+    if (category == NULL)
+        category = PyExc_RuntimeWarning;
+
+    res = do_warn(message, category, stack_level);
+    Py_DECREF(message);
+    if (res == NULL)
+        return -1;
+    Py_DECREF(res);
+
+    return 0;
+}
+
+/* PyErr_Warn is only for backwards compatability and will be removed.
+   Use PyErr_WarnEx instead. */
+
+#undef PyErr_Warn
+
+PyAPI_FUNC(int)
+PyErr_Warn(PyObject *category, char *text)
+{
+    return PyErr_WarnEx(category, text, 1);
+}
+
+/* Warning with explicit origin */
+int
+PyErr_WarnExplicit(PyObject *category, const char *text,
+                   const char *filename_str, int lineno,
+                   const char *module_str, PyObject *registry)
+{
+    PyObject *res;
+    PyObject *message = PyUnicode_FromString(text);
+    PyObject *filename = PyUnicode_FromString(filename_str);
+    PyObject *module = NULL;
+    int ret = -1;
+
+    if (message == NULL || filename == NULL)
+        goto exit;
+    if (module_str != NULL) {
+        module = PyUnicode_FromString(module_str);
+            if (module == NULL)
+                goto exit;
+    }
+
+    if (category == NULL)
+        category = PyExc_RuntimeWarning;
+    res = warn_explicit(category, message, filename, lineno, module, registry,
+                        NULL);
+    if (res == NULL)
+        goto exit;
+    Py_DECREF(res);
+    ret = 0;
+
+ exit:
+    Py_XDECREF(message);
+    Py_XDECREF(module);
+    Py_XDECREF(filename);
+    return ret;
+}
+
+
+PyDoc_STRVAR(warn_doc,
+"Issue a warning, or maybe ignore it or raise an exception.");
+
+PyDoc_STRVAR(warn_explicit_doc,
+"Low-level inferface to warnings functionality.");
+
+static PyMethodDef warnings_functions[] = {
+    {"warn", (PyCFunction)warnings_warn, METH_VARARGS | METH_KEYWORDS,
+        warn_doc},
+    {"warn_explicit", (PyCFunction)warnings_warn_explicit,
+        METH_VARARGS | METH_KEYWORDS, warn_explicit_doc},
+    // XXX(brett.cannon): add showwarning?
+    // XXX(brett.cannon): Reasonable to add formatwarning?
+    {NULL, NULL}	        /* sentinel */
+};
+
+
+static PyObject *
+create_filter(PyObject *category, const char *action)
+{
+    static PyObject *ignore_str = NULL;
+    static PyObject *error_str = NULL;
+    static PyObject *default_str = NULL;
+    PyObject *action_obj = NULL;
+    PyObject *lineno, *result;
+
+    if (!strcmp(action, "ignore")) {
+        if (ignore_str == NULL) {
+            ignore_str = PyUnicode_InternFromString("ignore");
+            if (ignore_str == NULL)
+                return NULL;
+        }
+        action_obj = ignore_str;
+    }
+    else if (!strcmp(action, "error")) {
+        if (error_str == NULL) {
+            error_str = PyUnicode_InternFromString("error");
+            if (error_str == NULL)
+                return NULL;
+        }
+        action_obj = error_str;
+    }
+    else if (!strcmp(action, "default")) {
+        if (default_str == NULL) {
+            default_str = PyUnicode_InternFromString("default");
+            if (default_str == NULL)
+                return NULL;
+        }
+        action_obj = default_str;
+    }
+    else {
+        Py_FatalError("unknown action");
+    }
+
+    /* This assumes the line number is zero for now. */
+    lineno = PyLong_FromLong(0);
+    if (lineno == NULL)
+        return NULL;
+    result = PyTuple_Pack(5, action_obj, Py_None, category, Py_None, lineno);
+    Py_DECREF(lineno);
+    return result;
+}
+
+static PyObject *
+init_filters(void)
+{
+    PyObject *filters = PyList_New(3);
+    const char *bytes_action;
+    if (filters == NULL)
+        return NULL;
+
+    PyList_SET_ITEM(filters, 0,
+                    create_filter(PyExc_PendingDeprecationWarning, "ignore"));
+    PyList_SET_ITEM(filters, 1, create_filter(PyExc_ImportWarning, "ignore"));
+    if (Py_BytesWarningFlag > 1)
+        bytes_action = "error";
+    else if (Py_BytesWarningFlag)
+        bytes_action = "default";
+    else
+        bytes_action = "ignore";
+    PyList_SET_ITEM(filters, 2, create_filter(PyExc_BytesWarning,
+                    bytes_action));
+
+    if (PyList_GET_ITEM(filters, 0) == NULL ||
+        PyList_GET_ITEM(filters, 1) == NULL ||
+        PyList_GET_ITEM(filters, 2) == NULL) {
+        Py_DECREF(filters);
+        return NULL;
+    }
+
+    return filters;
+}
+
+
+PyMODINIT_FUNC
+_PyWarnings_Init(void)
+{
+    PyObject *m, *default_action;
+
+    m = Py_InitModule3(MODULE_NAME, warnings_functions, warnings__doc__);
+    if (m == NULL)
+        return;
+
+    _filters = init_filters();
+    if (_filters == NULL)
+        return;
+    Py_INCREF(_filters);
+    if (PyModule_AddObject(m, "filters", _filters) < 0)
+        return;
+
+    _once_registry = PyDict_New();
+    if (_once_registry == NULL)
+        return;
+    Py_INCREF(_once_registry);
+    if (PyModule_AddObject(m, "once_registry", _once_registry) < 0)
+        return;
+
+    default_action = PyUnicode_InternFromString("default");
+    if (default_action == NULL)
+        return;
+    if (PyModule_AddObject(m, DEFAULT_ACTION_NAME, default_action) < 0)
+        return;
+}