[ruby-core:121054] [Ruby master Bug#21139] Prism and parse.y parses `it = it` differently

[ruby-core:121054] [Ruby master Bug#21139] Prism and parse.y parses `it = it` differently

[tompng (tomoya ishida) via ruby-core]

Issue #21139 has been reported by tompng (tomoya ishida).

----------------------------------------
Bug #21139: Prism and parse.y parses `it = it` differently
https://bugs.ruby-lang.org/issues/21139

* Author: tompng (tomoya ishida)
* Status: Assigned
* Assignee: prism
* ruby -v: ruby 3.5.0dev (2025-02-14T16:49:52Z master ee181d1bb7) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
~~~
# ruby --parser=parse.y -e "42.tap { it = it; p it }"
nil
# ruby --parser=prism -e "42.tap { it = it; p it }"
42
~~~




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[ruby-core:121061] [Ruby master Bug#21139] Prism and parse.y parses `it = it` differently

[matz (Yukihiro Matsumoto) via ruby-core]

Issue #21139 has been updated by matz (Yukihiro Matsumoto).


Assignment to `it` should be prohibited in the long run. Temporarily, I vote for Prism behavior.

Matz.

By the way, how can I clear assignee of the issue on Redmine?

----------------------------------------
Bug #21139: Prism and parse.y parses `it = it` differently
https://bugs.ruby-lang.org/issues/21139#change-111974

* Author: tompng (tomoya ishida)
* Status: Assigned
* Assignee: prism
* ruby -v: ruby 3.5.0dev (2025-02-14T16:49:52Z master ee181d1bb7) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
~~~
# ruby --parser=parse.y -e "42.tap { it = it; p it }"
nil
# ruby --parser=prism -e "42.tap { it = it; p it }"
42
~~~




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[ruby-core:121063] [Ruby master Bug#21139] Prism and parse.y parses `it = it` differently

[nobu (Nobuyoshi Nakada) via ruby-core]

Issue #21139 has been updated by nobu (Nobuyoshi Nakada).


matz (Yukihiro Matsumoto) wrote in #note-1:
> Assignment to `it` should be prohibited in the long run. Temporarily, I vote for Prism behavior.

1. Currently, `it` is an ordinary local variable if assigned syntactically.
2. And a local variable is `nil` before assigned, even in its RHS, at the runtime.

The behavior in parse.y obeys above principles.

Do you want to change the rule 1, make `it` always special?

----------------------------------------
Bug #21139: Prism and parse.y parses `it = it` differently
https://bugs.ruby-lang.org/issues/21139#change-111976

* Author: tompng (tomoya ishida)
* Status: Assigned
* Assignee: prism
* ruby -v: ruby 3.5.0dev (2025-02-14T16:49:52Z master ee181d1bb7) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
~~~
# ruby --parser=parse.y -e "42.tap { it = it; p it }"
nil
# ruby --parser=prism -e "42.tap { it = it; p it }"
42
~~~




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[ruby-core:121270] [Ruby master Bug#21139] Prism and parse.y parses `it = it` differently

[alanwu (Alan Wu) via ruby-core]

Issue #21139 has been updated by alanwu (Alan Wu).

File clipboard-202503081702-idzz2.png added
Status changed from Assigned to Open
Assignee deleted (prism)

matz (Yukihiro Matsumoto) wrote in #note-1:
> By the way, how can I clear assignee of the issue on Redmine?

The null option in the menu is the very first one and is rendered with a tiny height to make it hard to mouse over. It's easier to pick it with arrow keys.
Maybe the UX could be improved by tweaking some settings? CC @hsbt 

![](clipboard-202503081702-idzz2.png)
 



----------------------------------------
Bug #21139: Prism and parse.y parses `it = it` differently
https://bugs.ruby-lang.org/issues/21139#change-112226

* Author: tompng (tomoya ishida)
* Status: Open
* ruby -v: ruby 3.5.0dev (2025-02-14T16:49:52Z master ee181d1bb7) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
~~~
# ruby --parser=parse.y -e "42.tap { it = it; p it }"
nil
# ruby --parser=prism -e "42.tap { it = it; p it }"
42
~~~


---Files--------------------------------
clipboard-202503081702-idzz2.png (22.6 KB)


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[ruby-core:121338] [Ruby master Bug#21139] Prism and parse.y parses `it = it` differently

[matz (Yukihiro Matsumoto) via ruby-core]

Issue #21139 has been updated by matz (Yukihiro Matsumoto).


I said I prefer Prism behavior to `parse.y`. But It was due to my misunderstanding. `it = it` should initialize the local variable named `it` and the value should be `nil`, just like other `x = x` assignment in Ruby.
In the future, all assignment to `it` could be prohibited, maybe.

Matz.


----------------------------------------
Bug #21139: Prism and parse.y parses `it = it` differently
https://bugs.ruby-lang.org/issues/21139#change-112308

* Author: tompng (tomoya ishida)
* Status: Open
* ruby -v: ruby 3.5.0dev (2025-02-14T16:49:52Z master ee181d1bb7) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
~~~
# ruby --parser=parse.y -e "42.tap { it = it; p it }"
nil
# ruby --parser=prism -e "42.tap { it = it; p it }"
42
~~~


---Files--------------------------------
clipboard-202503081702-idzz2.png (22.6 KB)


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[ruby-core:121343] [Ruby master Bug#21139] Prism and parse.y parses `it = it` differently

[kddnewton (Kevin Newton) via ruby-core]

Issue #21139 has been updated by kddnewton (Kevin Newton).

Assignee set to prism

----------------------------------------
Bug #21139: Prism and parse.y parses `it = it` differently
https://bugs.ruby-lang.org/issues/21139#change-112315

* Author: tompng (tomoya ishida)
* Status: Open
* Assignee: prism
* ruby -v: ruby 3.5.0dev (2025-02-14T16:49:52Z master ee181d1bb7) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
~~~
# ruby --parser=parse.y -e "42.tap { it = it; p it }"
nil
# ruby --parser=prism -e "42.tap { it = it; p it }"
42
~~~


---Files--------------------------------
clipboard-202503081702-idzz2.png (22.6 KB)


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