CPython needs C99

Author: encukou

Lib/test/datetimetester.py

@@ -1807,7 +1807,7 @@ def test_bool(self):
         self.assertTrue(self.theclass.min)
         self.assertTrue(self.theclass.max)
 
-    def test_strftime_y2k(self):
+    def check_strftime_y2k(self, specifier):
         # Test that years less than 1000 are 0-padded; note that the beginning
         # of an ISO 8601 year may fall in an ISO week of the year before, and
         # therefore needs an offset of -1 when formatting with '%G'.
@@ -1821,22 +1821,28 @@ def test_strftime_y2k(self):
             (1000, 0),
             (1970, 0),
         )
-        specifiers = 'YG'
-        if _time.strftime('%F', (1900, 1, 1, 0, 0, 0, 0, 1, 0)) == '1900-01-01':
-            specifiers += 'FC'
         for year, g_offset in dataset:
-            for specifier in specifiers:
-                with self.subTest(year=year, specifier=specifier):
-                    d = self.theclass(year, 1, 1)
-                    if specifier == 'G':
-                        year += g_offset
-                    if specifier == 'C':
-                        expected = f"{year // 100:02d}"
-                    else:
-                        expected = f"{year:04d}"
-                        if specifier == 'F':
-                            expected += f"-01-01"
-                    self.assertEqual(d.strftime(f"%{specifier}"), expected)
+            with self.subTest(year=year, specifier=specifier):
+                d = self.theclass(year, 1, 1)
+                if specifier == 'G':
+                    year += g_offset
+                if specifier == 'C':
+                    expected = f"{year // 100:02d}"
+                else:
+                    expected = f"{year:04d}"
+                    if specifier == 'F':
+                        expected += f"-01-01"
+                self.assertEqual(d.strftime(f"%{specifier}"), expected)
+
+    def test_strftime_y2k(self):
+        self.check_strftime_y2k('Y')
+        self.check_strftime_y2k('G')
+
+    def test_strftime_y2k_c99(self):
+        # CPython requires C11; specifiers new in C99 must work.
+        # (Other implementations may want to disable this test.)
+        self.check_strftime_y2k('F')
+        self.check_strftime_y2k('C')
 
     def test_replace(self):
         cls = self.theclass

Modules/_datetimemodule.c

@@ -1781,24 +1781,6 @@ normalize_century(void)
     return cache;
 }
 
-/* Check whether C99-specific strftime specifiers are supported. */
-inline static int
-strftime_c99_support(void)
-{
-    static int cache = -1;
-    if (cache < 0) {
-        char full_date[11];
-        struct tm date = {
-            .tm_year = 0,
-            .tm_mon = 0,
-            .tm_mday = 1
-        };
-        cache = (strftime(full_date, sizeof(full_date), "%F", &date) &&
-                 strcmp(full_date, "1900-01-01") == 0);
-    }
-    return cache;
-}
-
 static PyObject *
 make_somezreplacement(PyObject *object, char *sep, PyObject *tzinfoarg)
 {
@@ -1970,8 +1952,8 @@ wrap_strftime(PyObject *object, PyObject *format, PyObject *timetuple,
             }
             replacement = freplacement;
         }
-        else if (normalize_century() && (ch == 'Y' || ch == 'G' ||
-                 (strftime_c99_support() && (ch == 'F' || ch == 'C'))))
+        else if (normalize_century()
+                 && (ch == 'Y' || ch == 'G' || ch == 'F' || ch == 'C'))
         {
             /* 0-pad year with century as necessary */
             PyObject *item = PySequence_GetItem(timetuple, 0);

Tools/c-analyzer/cpython/ignored.tsv

@@ -227,7 +227,6 @@ Modules/_datetimemodule.c	parse_hh_mm_ss_ff	correction	-
 Modules/_datetimemodule.c	time_isoformat	specs	-
 Modules/_datetimemodule.c	-	capi_types	-
 Modules/_datetimemodule.c	normalize_century	cache	-
-Modules/_datetimemodule.c	strftime_c99_support	cache	-
 Modules/_decimal/_decimal.c	-	cond_map_template	-
 Modules/_decimal/_decimal.c	-	dec_signal_string	-
 Modules/_decimal/_decimal.c	-	dflt_ctx	-