Avoid assert failure when NULL EC is expected

After 5680c38c75aeb5cbd219aafa8eb48c315f287d97, postponed job APIs now
expect to be called on native threads not managed by Ruby and handles
getting a NULL execution context. However, in debug builds the change
runs into an assertion failure with GET_EC() which asserts that EC is
non-NULL. Avoid the assertion failure by passing `false` for `expect_ec`
instead as the intention is to handle when there is no EC.

Add a test from John Crepezzi and John Hawthorn to exercise this
situation.

See GH-4108
See GH-5094

[Bug #17573]

Co-authored-by: John Hawthorn <john@hawthorn.email>
Co-authored-by: John Crepezzi <john.crepezzi@gmail.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/ext/-test-/postponed_job/postponed_job.c b/ext/-test-/postponed_job/postponed_job.c
index d8684d475a..fa57bef6f5 100644
--- a/ext/-test-/postponed_job/postponed_job.c
+++ b/ext/-test-/postponed_job/postponed_job.c
@@ -58,6 +58,34 @@ pjob_call_direct(VALUE self, VALUE obj)
     return self;
 }
 
+#ifdef HAVE_PTHREAD_H
+#include <pthread.h>
+
+static void *
+pjob_register_in_c_thread_i(void *obj)
+{
+    rb_postponed_job_register_one(0, pjob_one_callback, (void *)obj);
+    rb_postponed_job_register_one(0, pjob_one_callback, (void *)obj);
+    rb_postponed_job_register_one(0, pjob_one_callback, (void *)obj);
+    return NULL;
+}
+
+static VALUE
+pjob_register_in_c_thread(VALUE self, VALUE obj)
+{
+    pthread_t thread;
+    if (pthread_create(&thread, NULL, pjob_register_in_c_thread_i, (void *)obj)) {
+        return Qfalse;
+    }
+
+    if (pthread_join(thread, NULL)) {
+        return Qfalse;
+    }
+
+    return Qtrue;
+}
+#endif
+
 void
 Init_postponed_job(VALUE self)
 {
@@ -65,5 +93,8 @@ Init_postponed_job(VALUE self)
     rb_define_module_function(mBug, "postponed_job_register", pjob_register, 1);
     rb_define_module_function(mBug, "postponed_job_register_one", pjob_register_one, 1);
     rb_define_module_function(mBug, "postponed_job_call_direct", pjob_call_direct, 1);
+#ifdef HAVE_PTHREAD_H
+    rb_define_module_function(mBug, "postponed_job_register_in_c_thread", pjob_register_in_c_thread, 1);
+#endif
 }