Simplify, don't have duplicate definitions.

`match = prefixmatch`

Author: gpshead

Lib/re/__init__.py

@@ -167,11 +167,8 @@ def prefixmatch(pattern, string, flags=0):
     a Match object, or None if no match was found."""
     return _compile(pattern, flags).prefixmatch(string)
 
-def match(pattern, string, flags=0):
-    """The original name for prefixmatch.  Equivalent behavior.
-    Try to apply the pattern at the start of the string, returning
-    a Match object, or None if no match was found."""
-    return _compile(pattern, flags).prefixmatch(string)
+# Our original less explicitly clear about the behavior name for prefixmatch.
+match = prefixmatch
 
 def fullmatch(pattern, string, flags=0):
     """Try to apply the pattern to all of the string, returning

Lib/test/test_inspect/test_inspect.py

@@ -5812,7 +5812,10 @@ def test_pwd_module_has_signatures(self):
 
     def test_re_module_has_signatures(self):
         import re
-        methods_no_signature = {'Match': {'group'}}
+        methods_no_signature = {
+                'Match': {'group'},
+                'Pattern': {'match'},  # It is now an alias for prefixmatch
+        }
         self._test_module_has_signatures(re,
                 methods_no_signature=methods_no_signature,
                 good_exceptions={'error', 'PatternError'})

Modules/_sre/clinic/sre.c.h

@@ -811,32 +811,6 @@ _sre_SRE_Pattern_prefixmatch_impl(PatternObject *self, PyTypeObject *cls,
     return match;
 }
 
-/*[clinic input]
-_sre.SRE_Pattern.match
-
-    cls: defining_class
-    /
-    string: object
-    pos: Py_ssize_t = 0
-    endpos: Py_ssize_t(c_default="PY_SSIZE_T_MAX") = sys.maxsize
-
-Matches zero or more characters at the beginning of the string.
-
-This is the legacy method name. Modern Python also provides it under the name
-'prefixmatch' to allow code to be explicitly clear about the intended behavior.
-
-[clinic start generated code]*/
-
-static PyObject *
-_sre_SRE_Pattern_match_impl(PatternObject *self, PyTypeObject *cls,
-                            PyObject *string, Py_ssize_t pos,
-                            Py_ssize_t endpos)
-/*[clinic end generated code: output=ec6208ea58a0cca0 input=7541a63c722fcfdf]*/
-{
-    /* TODO - https://github.com/python/cpython/issues/86519 - If we ever
-     * want a PendingDeprecationWarning here, wait until year >=2030. */
-    return _sre_SRE_Pattern_prefixmatch_impl(self, cls, string, pos, endpos);
-}
 
 /*[clinic input]
 _sre.SRE_Pattern.fullmatch
@@ -2929,23 +2903,6 @@ _sre_SRE_Scanner_prefixmatch_impl(ScannerObject *self, PyTypeObject *cls)
     return match;
 }
 
-/*[clinic input]
-_sre.SRE_Scanner.match
-
-    cls: defining_class
-    /
-
-[clinic start generated code]*/
-
-static PyObject *
-_sre_SRE_Scanner_match_impl(ScannerObject *self, PyTypeObject *cls)
-/*[clinic end generated code: output=6e22c149dc0f0325 input=b5146e1f30278cb7]*/
-{
-    /* TODO(https://bugs.python.org/issue42353): Plan if we EVER want to
-     * issue a PendingDeprecationWarning here. */
-    return _sre_SRE_Scanner_prefixmatch_impl(self, cls);
-}
-
 
 /*[clinic input]
 _sre.SRE_Scanner.search
@@ -3206,7 +3163,7 @@ pattern_richcompare(PyObject *lefto, PyObject *righto, int op)
 
 static PyMethodDef pattern_methods[] = {
     _SRE_SRE_PATTERN_PREFIXMATCH_METHODDEF
-    _SRE_SRE_PATTERN_MATCH_METHODDEF
+    {"match", NULL},  /* filled in by sre_exec() */
     _SRE_SRE_PATTERN_FULLMATCH_METHODDEF
     _SRE_SRE_PATTERN_SEARCH_METHODDEF
     _SRE_SRE_PATTERN_SUB_METHODDEF
@@ -3334,7 +3291,7 @@ static PyType_Spec match_spec = {
 
 static PyMethodDef scanner_methods[] = {
     _SRE_SRE_SCANNER_PREFIXMATCH_METHODDEF
-    _SRE_SRE_SCANNER_MATCH_METHODDEF
+    {"match", NULL},  /* filled in by sre_exec() */
     _SRE_SRE_SCANNER_SEARCH_METHODDEF
     {NULL, NULL}
 };
@@ -3438,11 +3395,40 @@ do {                                                                \
         }                                                 \
 } while (0)
 
+
+static void
+copy_prefixmatch_method_def_to_match(PyMethodDef *method_defs)
+{
+    /* We could implement logic to scan the null filled sentry
+     * terminated list for the two method names.  But we're a
+     * bunch of static structs.  We just guarantee their position
+     * and flag deviation from this via debug build assertions.
+     */
+    assert(method_defs);
+    PyMethodDef *prefixmatch_md = &method_defs[0];
+    assert(prefixmatch_md->ml_name != NULL);
+    assert(strcmp(prefixmatch_md->ml_name, "prefixmatch") == 0);
+
+    PyMethodDef *match_md = &method_defs[1];
+    assert(match_md->ml_name != NULL);
+    assert(strcmp(match_md->ml_name, "match") == 0);
+    /* If the public stable C API struct ever changed (!) and
+     * somehow wound up with unexpected layout and alignment
+     * constraints, fix the memcpy below. */
+    assert(offsetof(PyMethodDef, ml_meth) == sizeof(char *));
+    memcpy(&match_md->ml_meth, &prefixmatch_md->ml_meth,
+           sizeof(PyMethodDef) - offsetof(PyMethodDef, ml_meth));
+}
+
+
 static int
 sre_exec(PyObject *m)
 {
     _sremodulestate *state;
 
+    copy_prefixmatch_method_def_to_match(pattern_methods);
+    copy_prefixmatch_method_def_to_match(scanner_methods);
+
     /* Create heap types */
     state = get_sre_module_state(m);
     CREATE_TYPE(m, state->Pattern_Type, &pattern_spec);