Print Ruby exception in test utils

4 files changed, 15 insertions, 2 deletions

diff --git a/yjit/bindgen/src/main.rs b/yjit/bindgen/src/main.rs
index df675304e8..b9f3651e0e 100644
--- a/yjit/bindgen/src/main.rs
+++ b/yjit/bindgen/src/main.rs
@@ -359,6 +359,7 @@ fn main() {
         .allowlist_function("rb_yjit_invokeblock_sp_pops")
         .allowlist_function("rb_yjit_set_exception_return")
         .allowlist_function("rb_yjit_str_concat_codepoint")
+        .allowlist_function("rb_zjit_print_exception")
         .allowlist_type("robject_offsets")
         .allowlist_type("rstring_offsets")
 
diff --git a/zjit.c b/zjit.c
index af11ac2949..21c257cd32 100644
--- a/zjit.c
+++ b/zjit.c
@@ -681,5 +681,14 @@ rb_iseq_set_zjit_payload(const rb_iseq_t *iseq, void *payload)
 // Primitives used by zjit.rb
 VALUE rb_zjit_assert_compiles(rb_execution_context_t *ec, VALUE self);
 
+void
+rb_zjit_print_exception(void)
+{
+    VALUE exception = rb_errinfo();
+    rb_set_errinfo(Qnil);
+    assert(RTEST(exception));
+    rb_warn("Ruby error: %"PRIsVALUE"", rb_funcall(exception, rb_intern("full_message"), 0));
+}
+
 // Preprocessed zjit.rb generated during build
 #include "zjit.rbinc"
diff --git a/zjit/src/cruby.rs b/zjit/src/cruby.rs
index dff8d301d6..c0093dd284 100644
--- a/zjit/src/cruby.rs
+++ b/zjit/src/cruby.rs
@@ -939,8 +939,10 @@ pub mod test_utils {
 
         let mut state: c_int = 0;
         unsafe { super::rb_protect(Some(callback_wrapper), VALUE((&mut data) as *mut _ as usize), &mut state) };
-        // TODO(alan): there should be a way to print the exception instead of swallowing it
-        assert_eq!(0, state, "Exceptional unwind in callback. Ruby exception?");
+        if state != 0 {
+            unsafe { rb_zjit_print_exception(); }
+            assert_eq!(0, state, "Exceptional unwind in callback. Ruby exception?");
+        }
 
         result.expect("Callback did not set result")
     }
diff --git a/zjit/src/cruby_bindings.inc.rs b/zjit/src/cruby_bindings.inc.rs
index 6c5a7c82bf..01da0bff47 100644
--- a/zjit/src/cruby_bindings.inc.rs
+++ b/zjit/src/cruby_bindings.inc.rs
@@ -1023,4 +1023,5 @@ unsafe extern "C" {
     pub fn rb_RCLASS_ORIGIN(c: VALUE) -> VALUE;
     pub fn rb_iseq_get_zjit_payload(iseq: *const rb_iseq_t) -> *mut ::std::os::raw::c_void;
     pub fn rb_iseq_set_zjit_payload(iseq: *const rb_iseq_t, payload: *mut ::std::os::raw::c_void);
+    pub fn rb_zjit_print_exception();
 }