Issue #15937 has been updated by luke-gru (Luke Gruber).


This is fixed if in `rb_str_init`, you return `str` right after existing check of `(orig == str)`, but then capacity won't change.

----------------------------------------
Bug #15937: Segmentation fault when String#initialize given same string with capacity field
https://bugs.ruby-lang.org/issues/15937#change-78686

* Author: luke-gru (Luke Gruber)
* Status: Closed
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
Reproduction steps:

string buffer corruption:
```ruby
s = "mystring"
s.__send__(:initialize, s, capacity: 1000)
puts s
```

segfault:

```ruby
s = "mystring that can't be embedded because it's too long and therefore must be allocated"
s.__send__(:initialize, s, capacity: 1000)
```

Thanks for your time :)



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