Handle panic in case of unsupported format in chrono

itsankitkp · itsankitkp · commit d4c2fd3b2531 · 2023-01-31T20:58:53.000+05:30
Chrono panics in case of unsupported formats, this patch handles such
cases and returns supplied format as a result.
diff --git a/Lib/test/test_time.py b/Lib/test/test_time.py
@@ -157,7 +157,8 @@ def test_sleep(self):
         self.assertRaises(ValueError, time.sleep, -1)
         time.sleep(1.2)
 
-    @unittest.skip("TODO: RUSTPYTHON, thread 'main' panicked at 'a Display implementation returned an error unexpectedly: Error'")
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
     def test_strftime(self):
         tt = time.gmtime(self.t)
         for directive in ('a', 'A', 'b', 'B', 'c', 'd', 'H', 'I',
diff --git a/extra_tests/snippets/stdlib_datetime.py b/extra_tests/snippets/stdlib_datetime.py
@@ -131,6 +131,10 @@ def __init__(self, offset, name):
 assert_raises(NotImplementedError, ne.utcoffset, dt)
 assert_raises(NotImplementedError, ne.dst, dt)
 
+# unsupport format in strptime should returns arg itself
+# XXX this fails because it runs in python not rustpython
+assert_equal(_time.strftime("%4Y"), "%4Y")
+
 # XXX: bug #1302
 # def test_normal(self):
 #fo = FixedOffset(3, "Three")
diff --git a/vm/src/stdlib/time.rs b/vm/src/stdlib/time.rs
@@ -207,8 +207,18 @@ mod time {
 
     #[pyfunction]
     fn strftime(format: PyStrRef, t: OptionalArg<PyStructTime>, vm: &VirtualMachine) -> PyResult {
+        use std::fmt::Write;
+
         let instant = t.naive_or_local(vm)?;
-        let formatted_time = instant.format(format.as_str()).to_string();
+        let mut formatted_time = String::new();
+
+        /*
+         * chrono doesn't support all formats and it
+         * raises an error if unsupported format is supplied.
+         * If error happens, we set result as input arg.
+         */
+        write!(&mut formatted_time, "{}", instant.format(format.as_str()))
+            .unwrap_or_else(|_| formatted_time = format.to_string());
         Ok(vm.ctx.new_str(formatted_time).into())
     }
 
