show warning for unused block

With verbopse mode (-w), the interpreter shows a warning if
a block is passed to a method which does not use the given block.

Warning on:

* the invoked method is written in C
* the invoked method is not `initialize`
* not invoked with `super`
* the first time on the call-site with the invoked method
  (`obj.foo{}` will be warned once if `foo` is same method)

[Feature #15554]

`Primitive.attr! :use_block` is introduced to declare that primitive
functions (written in C) will use passed block.

For minitest, test needs some tweak, so use
https://github.com/minitest/minitest/commit/ea9caafc0754b1d6236a490d59e624b53209734a
for `test-bundled-gems`.

1 files changed, 1 insertions, 0 deletions

diff --git a/vm_core.h b/vm_core.h
index 2a9d5f906f..57d90b343f 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -418,6 +418,7 @@ struct rb_iseq_constant_body {
             unsigned int ruby2_keywords: 1;
             unsigned int anon_rest: 1;
             unsigned int anon_kwrest: 1;
+            unsigned int use_block: 1;
         } flags;
 
         unsigned int size;