gh-122272: Guarantee specifiers %F and %C for datetime.strftime to be 0-padded (GH-122436)

1 files changed, 28 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 9daace7..3c1dc1c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -6703,6 +6703,34 @@ then
   [Define if year with century should be normalized for strftime.])
 fi
 
+AC_CACHE_CHECK([whether C99-specific strftime specifiers are supported], [ac_cv_strftime_c99_support], [
+AC_RUN_IFELSE([AC_LANG_SOURCE([[
+#include <time.h>
+#include <string.h>
+
+int main(void)
+{
+  char full_date[11];
+  struct tm date = {
+    .tm_year = 0,
+    .tm_mon = 0,
+    .tm_mday = 1
+  };
+  if (strftime(full_date, sizeof(full_date), "%F", &date) && !strcmp(full_date, "1900-01-01")) {
+    return 0;
+  }
+  return 1;
+}
+]])],
+[ac_cv_strftime_c99_support=yes],
+[ac_cv_strftime_c99_support=no],
+[ac_cv_strftime_c99_support=no])])
+if test "$ac_cv_strftime_c99_support" = yes
+then
+  AC_DEFINE([Py_STRFTIME_C99_SUPPORT], [1],
+  [Define if C99-specific strftime specifiers are supported.])
+fi
+
 dnl check for ncursesw/ncurses and panelw/panel
 dnl NOTE: old curses is not detected.
 dnl have_curses=[no, yes]