`ensure` section is not executed if the function exits via a return in a proc

[suetanvil]

In the following function:

def outer
  puts "open"
  proc{ return 42 }.call
ensure
  puts "close"
end

the ensure block is not executed in this case, as it is with CRuby and JRuby.

Replacing the proc with just return 42 behaves as expected. So does exiting via a block argument, like this:

def inner(&block)
  puts "open"
  return block.call
ensure
  puts "close"
end

def outer
  inner { return 42 }
end

outer()

[dearblue]

Thank you for the report.
The cause that comes to mind is #5060, so I checked and it is not reproduced in mruby 2.1.2, but it is reproduced in mruby 3.0 and later. 🙀
I will fix it.

[dearblue]

A working branch with the RBreak tag organized does not seem to cause any problems. Please wait a moment while I try to summarize.

The cause of the problem was that we did not do the necessary processing.
I will post a patch here just to fix it, if it is urgently needed.
I think it can be applied to mruby 3.0.0 or later by changing the form a little.

diff --git a/src/vm.c b/src/vm.c
index b504fdcc9..10a817e7a 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -1065,10 +1065,11 @@ mrb_yield_cont(mrb_state *mrb, mrb_value b, mrb_value self, mrb_int argc, const
   f(RBREAK_TAG_BREAK_UPPER, 1) \
   f(RBREAK_TAG_BREAK_INTARGET, 2) \
   f(RBREAK_TAG_RETURN_BLOCK, 3) \
-  f(RBREAK_TAG_RETURN, 4) \
-  f(RBREAK_TAG_RETURN_TOPLEVEL, 5) \
-  f(RBREAK_TAG_JUMP, 6) \
-  f(RBREAK_TAG_STOP, 7)
+  f(RBREAK_TAG_RETURN_BLOCK_INTARGET, 4) \
+  f(RBREAK_TAG_RETURN, 5) \
+  f(RBREAK_TAG_RETURN_TOPLEVEL, 6) \
+  f(RBREAK_TAG_JUMP, 7) \
+  f(RBREAK_TAG_STOP, 8)

 #define RBREAK_TAG_DEFINE(tag, i) tag = i,
 enum {
@@ -1076,7 +1077,7 @@ enum {
 };
 #undef RBREAK_TAG_DEFINE

-#define RBREAK_TAG_BIT          3
+#define RBREAK_TAG_BIT          4
 #define RBREAK_TAG_BIT_OFF      8
 #define RBREAK_TAG_MASK         (~(~UINT32_C(0) << RBREAK_TAG_BIT))

@@ -2294,6 +2295,14 @@ RETRY_TRY_BLOCK:
               pc = ci->pc;
             }
             proc = ci->proc;
+            CHECKPOINT_RESTORE(RBREAK_TAG_RETURN_BLOCK_INTARGET) {
+              cibase = mrb->c->cibase;
+              dst = top_proc(mrb, proc);
+            }
+            CHECKPOINT_MAIN(RBREAK_TAG_RETURN_BLOCK_INTARGET) {
+              UNWIND_ENSURE(mrb, ci, pc, RBREAK_TAG_RETURN_BLOCK_INTARGET, proc, v);
+            }
+            CHECKPOINT_END(RBREAK_TAG_RETURN_BLOCK_INTARGET);
             mrb->exc = NULL; /* clear break object */
             break;
           }

[suetanvil]

Thank you for the patch, but it is easy enough to work around. I submitted the issue so that you would be aware of it.