[ruby-core:120618] [Ruby master Bug#21029] Prism behavior for `defined? (;x)` differs

[ruby-core:120618] [Ruby master Bug#21029] Prism behavior for `defined? (;x)` differs

[qnighy (Masaki Hara) via ruby-core]

Issue #21029 has been reported by qnighy (Masaki Hara).

----------------------------------------
Bug #21029: Prism behavior for `defined? (;x)` differs
https://bugs.ruby-lang.org/issues/21029

* Author: qnighy (Masaki Hara)
* Status: Open
* ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Prism has a different behavior for `(;expr)` when used in `defined?` predicate:

```console
% ./miniruby --parser=prism -e "p defined? (;x)"
nil
% ./miniruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

Although not a significant difference, aligning either of them with the other would be better.



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[ruby-core:120624] [Ruby master Bug#21029] Prism behavior for `defined? (;x)` differs

[kddnewton (Kevin Newton) via ruby-core]

Issue #21029 has been updated by kddnewton (Kevin Newton).

Assignee set to prism

----------------------------------------
Bug #21029: Prism behavior for `defined? (;x)` differs
https://bugs.ruby-lang.org/issues/21029#change-111454

* Author: qnighy (Masaki Hara)
* Status: Open
* Assignee: prism
* ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Prism has a different behavior for `(;expr)` when used in `defined?` predicate:

```console
% ./miniruby --parser=prism -e "p defined? (;x)"
nil
% ./miniruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

Although not a significant difference, aligning either of them with the other would be better.



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[ruby-core:120673] [Ruby master Bug#21029] Prism behavior for `defined? (;x)` differs

[kddnewton (Kevin Newton) via ruby-core]

Issue #21029 has been updated by kddnewton (Kevin Newton).


I think we should change `parse.y` to match this behavior. I will ask around.

----------------------------------------
Bug #21029: Prism behavior for `defined? (;x)` differs
https://bugs.ruby-lang.org/issues/21029#change-111497

* Author: qnighy (Masaki Hara)
* Status: Open
* Assignee: prism
* ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Prism has a different behavior for `(;expr)` when used in `defined?` predicate:

```console
% ./miniruby --parser=prism -e "p defined? (;x)"
nil
% ./miniruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

Although not a significant difference, aligning either of them with the other would be better.



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[ruby-core:120966] [Ruby master Bug#21029] Prism behavior for `defined? (;x)` differs

[matz (Yukihiro Matsumoto) via ruby-core]

Issue #21029 has been updated by matz (Yukihiro Matsumoto).


I think compound expressions (expressions (including empty) concatenated by semicolons) should be “expression” as `parse.y`.
It makes `defined?` simpler. I know the current `defined?` behavior recursively check for defined-ness (e.g., method parameters), I don't think we need that complexity here.

Matz.

----------------------------------------
Bug #21029: Prism behavior for `defined? (;x)` differs
https://bugs.ruby-lang.org/issues/21029#change-111865

* Author: qnighy (Masaki Hara)
* Status: Assigned
* Assignee: prism
* ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Prism has a different behavior for `(;expr)` when used in `defined?` predicate:

```console
% ./miniruby --parser=prism -e "p defined? (;x)"
nil
% ./miniruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

Although not a significant difference, aligning either of them with the other would be better.



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[ruby-core:120968] [Ruby master Bug#21029] Prism behavior for `defined? (;x)` differs

[qnighy (Masaki Hara) via ruby-core]

Issue #21029 has been updated by qnighy (Masaki Hara).


> I think compound expressions (expressions (including empty) concatenated by semicolons) should be “expression” as `parse.y`.

Interestingly enough though:

```
% ruby --parser=prism -e "p defined? (x;)"
nil
% ruby --parser=parse.y -e "p defined? (x;)"
nil

% ruby --parser=prism -e "p defined? (;x)"
nil
% ruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

----------------------------------------
Bug #21029: Prism behavior for `defined? (;x)` differs
https://bugs.ruby-lang.org/issues/21029#change-111867

* Author: qnighy (Masaki Hara)
* Status: Assigned
* Assignee: prism
* ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Prism has a different behavior for `(;expr)` when used in `defined?` predicate:

```console
% ./miniruby --parser=prism -e "p defined? (;x)"
nil
% ./miniruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

Although not a significant difference, aligning either of them with the other would be better.



-- 
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[ruby-core:120988] [Ruby master Bug#21029] Prism behavior for `defined? (;x)` differs

[kddnewton (Kevin Newton) via ruby-core]

Issue #21029 has been updated by kddnewton (Kevin Newton).


@matz for what it's worth, it makes it much more complicated in the Prism compiler because we don't have empty statements. So it's not a recursive situation at the moment, it's just a single statement.

As @qnighy points out, should this be "expression" for when there is a trailing `;`?

----------------------------------------
Bug #21029: Prism behavior for `defined? (;x)` differs
https://bugs.ruby-lang.org/issues/21029#change-111892

* Author: qnighy (Masaki Hara)
* Status: Assigned
* Assignee: prism
* ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Prism has a different behavior for `(;expr)` when used in `defined?` predicate:

```console
% ./miniruby --parser=prism -e "p defined? (;x)"
nil
% ./miniruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

Although not a significant difference, aligning either of them with the other would be better.



-- 
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[ruby-core:121329] [Ruby master Bug#21029] Prism behavior for `defined? (;x)` differs

[mame (Yusuke Endoh) via ruby-core]

Issue #21029 has been updated by mame (Yusuke Endoh).


Discussed at the dev meeting.

kddnewton (Kevin Newton) wrote in #note-6:
> As @qnighy points out, should this be "expression" for when there is a trailing `;`?

@matz said "yes"; `defined? (x;)` should also return `"expression"`.

----------------------------------------
Bug #21029: Prism behavior for `defined? (;x)` differs
https://bugs.ruby-lang.org/issues/21029#change-112296

* Author: qnighy (Masaki Hara)
* Status: Assigned
* Assignee: prism
* ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Prism has a different behavior for `(;expr)` when used in `defined?` predicate:

```console
% ./miniruby --parser=prism -e "p defined? (;x)"
nil
% ./miniruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

Although not a significant difference, aligning either of them with the other would be better.



-- 
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[ruby-core:121401] [Ruby Bug#21029] Prism behavior for `defined? (;x)` differs

[kddnewton (Kevin Newton) via ruby-core]

Issue #21029 has been updated by kddnewton (Kevin Newton).


I have updated Prism with https://github.com/ruby/ruby/commit/adaaa7878ebee62888bf3547d14c1db4938da88a, but the added test fails for `parse.y`. I haven't had a chance to look at it yet, but maybe someone else with more familiarity could.

----------------------------------------
Bug #21029: Prism behavior for `defined? (;x)` differs
https://bugs.ruby-lang.org/issues/21029#change-112376

* Author: qnighy (Masaki Hara)
* Status: Assigned
* Assignee: prism
* ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Prism has a different behavior for `(;expr)` when used in `defined?` predicate:

```console
% ./miniruby --parser=prism -e "p defined? (;x)"
nil
% ./miniruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

Although not a significant difference, aligning either of them with the other would be better.



-- 
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[ruby-core:121402] [Ruby Bug#21029] Prism behavior for `defined? (;x)` differs

[kddnewton (Kevin Newton) via ruby-core]

Issue #21029 has been updated by kddnewton (Kevin Newton).

Assignee deleted (prism)

----------------------------------------
Bug #21029: Prism behavior for `defined? (;x)` differs
https://bugs.ruby-lang.org/issues/21029#change-112377

* Author: qnighy (Masaki Hara)
* Status: Assigned
* ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Prism has a different behavior for `(;expr)` when used in `defined?` predicate:

```console
% ./miniruby --parser=prism -e "p defined? (;x)"
nil
% ./miniruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

Although not a significant difference, aligning either of them with the other would be better.



-- 
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[ruby-core:122679] [Ruby Bug#21029] Prism behavior for `defined? (;x)` differs

[S_H_ (Shun Hiraoka) via ruby-core]

Issue #21029 has been updated by S_H_ (Shun Hiraoka).


I've fixed that defined? (x;) returns an expression when using parse.y.

https://github.com/ruby/ruby/pull/13821

However, I have a little skeptical about whether this change is a good idea. If any other good suggestions, I would appreciate it if you could comment.

----------------------------------------
Bug #21029: Prism behavior for `defined? (;x)` differs
https://bugs.ruby-lang.org/issues/21029#change-113959

* Author: qnighy (Masaki Hara)
* Status: Closed
* ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Prism has a different behavior for `(;expr)` when used in `defined?` predicate:

```console
% ./miniruby --parser=prism -e "p defined? (;x)"
nil
% ./miniruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

Although not a significant difference, aligning either of them with the other would be better.



-- 
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[ruby-core:122680] [Ruby Bug#21029] Prism behavior for `defined? (;x)` differs

[kddnewton (Kevin Newton) via ruby-core]

Issue #21029 has been updated by kddnewton (Kevin Newton).


@S_H_ I agree, I think the overhead is not worth it in this case and we should pretend the `;` do not exist on both cases.

----------------------------------------
Bug #21029: Prism behavior for `defined? (;x)` differs
https://bugs.ruby-lang.org/issues/21029#change-113960

* Author: qnighy (Masaki Hara)
* Status: Closed
* ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Prism has a different behavior for `(;expr)` when used in `defined?` predicate:

```console
% ./miniruby --parser=prism -e "p defined? (;x)"
nil
% ./miniruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

Although not a significant difference, aligning either of them with the other would be better.



-- 
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[ruby-core:122741] [Ruby Bug#21029] Prism behavior for `defined? (;x)` differs

[S_H_ (Shun Hiraoka) via ruby-core]

Issue #21029 has been updated by S_H_ (Shun Hiraoka).



I agree that consistent behavior between both cases would be ideal.  
Given the current structure of `parse.y`, wrapping with `NODE_BLOCK` seems like the most straightforward approach to make both `defined?(;x)` and `defined?(x;)` return `"expression"`.

With my current changes, both forms now generate the same AST nodes, which I believe improves consistency across the board.

Also, I want to clarify my earlier comment about being "skeptical" — I was specifically referring to adding new parameters to the `parser_params` struct, not to the `NODE_BLOCK` wrapping approach itself. Sorry for any confusion caused.

Right now, the `defined?(x;)` test is failing on `parse.y`, which makes it hard to assess whether changes to `universal_parser.c` or other components are affecting the `parse.y` behavior. This adds friction when trying to work on parser-related modifications.

From a maintenance standpoint, I believe fixing this failing test would help ensure that future `parse.y` changes can be validated more reliably.  
Would you be open to keeping this change in order to maintain test consistency?


----------------------------------------
Bug #21029: Prism behavior for `defined? (;x)` differs
https://bugs.ruby-lang.org/issues/21029#change-114022

* Author: qnighy (Masaki Hara)
* Status: Closed
* ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Prism has a different behavior for `(;expr)` when used in `defined?` predicate:

```console
% ./miniruby --parser=prism -e "p defined? (;x)"
nil
% ./miniruby --parser=parse.y -e "p defined? (;x)"
"expression"
```

Although not a significant difference, aligning either of them with the other would be better.



-- 
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