Applied in changeset trunk|r59183.

fix return in toplevel rescue/ensure

• compile.c (iseq_compile_each0): throw TAG_RETURN at return in
  toplevel rescue/ensure to adjust VM stack properly.
  [ruby-core:81777] [Bug ]

• vm_insnhelper.c (vm_throw_start): allow return in toplevel
  rescue/ensure.

Seems incomplete.

% ./miniruby -ve 'begin raise ensure return end and self'
ruby 2.5.0dev (2017-06-27 trunk 59183) [x86_64-darwin15]
-- raw disasm--------
 [none]
 0000 trace                1                                           (   1)
 <L001>
 0002 putself                                                          (   1)
 0003 opt_send_without_block <callinfo:raise, 0>, <call cache>         (   1)
 0006 pop                                                              (   1)
 <L002>
 adjust: [label: -1]
 0007 putnil                                                           (   1)
 0008 leave                                                            (   1)
 <L003>
 0009 pop                                                              (   1)
 0010 dup                                                              (   1)
 0011 branchunless         <L000>                                      (   1)
*0013 pop                                                              (   1)
 0014 putself                                                          (   1)
 <L000>
 0015 leave                                                            (   1)
---------------------
-e:1: argument stack underflow (-1)
Traceback (most recent call last):
-e: compile error (SyntaxError)
[1]    48279 exit 1     ./miniruby -ve 'begin raise ensure return end and self'

Applied in changeset trunk|r59184.

fix return in toplevel ensure

• compile.c (iseq_compile_each0): adjust stack after return in
  toplevel ensure, when the value is used.
  [ruby-core:81777] [Bug ]

ruby_2_4 r59493 merged revision(s) 59183,59184.