From: merch-redmine@...
Date: 2021-08-10T23:00:13+00:00
Subject: [ruby-dev:51093] [Ruby master Bug#12540] test failures when SHARABLE_MIDDLE_SUBSTRING=1

Issue #12540 has been updated by jeremyevans0 (Jeremy Evans).


I think this was caused by commit:a707ab4bc8a29241440f56696098efa2f7f3ff45, which removed the term filling if SHARABLE_MIDDLE_SUBSTRING was enabled. I submitted a pull request that basically reverts that commit: https://github.com/ruby/ruby/pull/4731.  I think the term filling can still be done safely, because the places where it was used already call `str_modify_keep_cr`, which should ensure they are dealing with a unique memory buffer.

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Bug #12540: test failures when SHARABLE_MIDDLE_SUBSTRING=1
https://bugs.ruby-lang.org/issues/12540#change-93226

* Author: znz (Kazuhiro NISHIYAMA)
* Status: Open
* Priority: Normal
* ruby -v: ruby 2.4.0dev (2016-07-02 trunk 55562) [x86_64-linux]
* Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN
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SHARABLE_MIDDLE_SUBSTRING=1 でビルドすると Test_StringCStr#test_wchar_lstrip!,Test_StringCStr#test_wchar_rstrip! が失敗します。

~~~
[16604/16757] Test_StringCStr#test_wchar_lstrip! = 0.00 s
  3) Failure:
Test_StringCStr#test_wchar_lstrip! [/home/vagrant/ruby/test/-ext-/string/test_cstr.rb:81]:
Expected {#<Encoding:UTF-16BE>=>"a",
 #<Encoding:UTF-16LE>=>"a",
 #<Encoding:UTF-32BE>=>"a",
 #<Encoding:UTF-32LE>=>"a"} to be empty.

[16606/16757] Test_StringCStr#test_wchar_rstrip! = 0.00 s
  4) Failure:
Test_StringCStr#test_wchar_rstrip! [/home/vagrant/ruby/test/-ext-/string/test_cstr.rb:85]:
Expected {#<Encoding:UTF-16BE>=>" ",
 #<Encoding:UTF-16LE>=>" ",
 #<Encoding:UTF-32BE>=>" ",
 #<Encoding:UTF-32LE>=>" "} to be empty.
~~~

原因を調べてみたところ、lstrip!,rstrip! だけ !SHARABLE_MIDDLE_SUBSTRING で TERM_FILL をくくっているからのようでした。

調べていて思ったのですが、個別に TERM_FILL を呼ぶかどうかを分岐するよりも、 SHARABLE_MIDDLE_SUBSTRING の値によって TERM_FILL 自体の定義を変更するようにした方が良いのではないでしょうか?



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