From: ko1@...
Date: 2015-08-03T08:20:59+00:00
Subject: [ruby-core:70229] [Ruby trunk - Bug #11409] {instance, module}_eval(&:foo) segfaults since r51243.

Issue #11409 has been updated by Koichi Sasada.


> It's true that changing that Qnil to Qfalse is the "cleaner" fix this time around, but I think using RTEST() to check for both is slightly more future-proof. I've submitted a pull request which takes the latter approach, in addition to adding a couple of tests to ensure something like this will be caught in future. I shall take no offense if your much greater familiarity with YARV tells you that using Qfalse there is the better solution.

I changed data structures around these part to have NULL (== Qfalse). If not, then it should be a bug. Using RTEST() hides these bugs.

I will check your test and introduce to our tests.
I will also add some assertions in codes to check Qnil.

Thaks,
Koichi

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Bug #11409: {instance,module}_eval(&:foo) segfaults since r51243.
https://bugs.ruby-lang.org/issues/11409#change-53657

* Author: D.E. Akers
* Status: Assigned
* Priority: Normal
* Assignee: Koichi Sasada
* ruby -v: ruby 2.3.0dev (2015-08-02 trunk 51469) [x86_64-linux]
* Backport: 
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The segfault only occurs when the argument is a `#to_proc`'d Symbol, and the receiver needn't actually respond to the named method.

This bug was introduced in [a rather large patch](http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=51243), and should almost certainly be fixed in one of the files modified therein. That said, I've discovered that removing the call to `rb_block_clear_env_self()` in `sym_to_proc()` prevents the segfault, as does setting `env->env[0]` to `Qfalse` rather than `Qnil` in `rb_block_clear_env_self()`. Neither of those is a proper fix, of course, but I hope this information may be of use to somebody more intimately familiar with Ruby's internals.



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