[ruby-core:105566] [Ruby master Bug#18242] Parser makes multiple assignment sad in confusing way

[ruby-core:105566] [Ruby master Bug#18242] Parser makes multiple assignment sad in confusing way

[danh337 (Dan Higgins)]

Issue #18242 has been reported by danh337 (Dan Higgins).

----------------------------------------
Bug #18242: Parser makes multiple assignment sad in confusing way
https://bugs.ruby-lang.org/issues/18242

* Author: danh337 (Dan Higgins)
* Status: Open
* Priority: Normal
* ruby -v: ruby 3.0.2p107 (2021-07-07 revision 0db68f0233) [x86_64-linux]
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
----------------------------------------
Example:
``` ruby
a, b = 2, 1     if 1 < 2     # Works
a, b = [2, 1]   if 1 < 2     # Works
(a, b) = 2, 1   if 1 < 2     # Works
(a, b) = [2, 1] if 1 < 2     # Works
(a, b = [2, 1]) if 1 < 2     # Works
a, b = 2, 1     unless 2 < 1 # Works
a, b = [2, 1]   unless 2 < 1 # Works
(a, b) = 2, 1   unless 2 < 1 # Works
(a, b) = [2, 1] unless 2 < 1 # Works
(a, b = [2, 1]) unless 2 < 1 # Works
1 < 2   and a, b = 2, 1      # SyntaxError
1 < 2   and a, b = [2, 1]    # SyntaxError
1 < 2   and (a, b) = 2, 1    # SyntaxError
1 < 2   and (a, b) = [2, 1]  # SyntaxError
(1 < 2) and a, b = 2, 1      # SyntaxError
(1 < 2) and a, b = [2, 1]    # SyntaxError
(1 < 2) and (a, b) = 2, 1    # SyntaxError
(1 < 2) and (a, b) = [2, 1]  # SyntaxError
1 < 2   and (a, b = 2, 1)    # Works
1 < 2   and (a, b = [2, 1])  # Works
2 < 1   or a, b = 2, 1       # SyntaxError
2 < 1   or a, b = [2, 1]     # SyntaxError
2 < 1   or (a, b) = 2, 1     # SyntaxError
2 < 1   or (a, b) = [2, 1]   # SyntaxError
(2 < 1) or a, b = 2, 1       # SyntaxError
(2 < 1) or a, b = [2, 1]     # SyntaxError
(2 < 1) or (a, b) = 2, 1     # SyntaxError
(2 < 1) or (a, b) = [2, 1]   # SyntaxError
2 < 1   or (a, b = 2, 1)     # Works
2 < 1   or (a, b = [2, 1])   # Works
```
Based on the precedence rules I've been able to find, all of these should work.

Believe it or not, there are cases where using `and` or `or` in a stanza of lines is much more readable.

Should the parser allow all of these? See attached driver script to reproduce this output.

---Files--------------------------------
driver.rb (1.17 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:105571] [Ruby master Feature#18242] Parser makes multiple assignment sad in confusing way

[jeremyevans0 (Jeremy Evans)]

Issue #18242 has been updated by jeremyevans0 (Jeremy Evans).

Backport deleted (2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN)
ruby -v deleted (ruby 3.0.2p107 (2021-07-07 revision 0db68f0233) [x86_64-linux])
Tracker changed from Bug to Feature
File and-or-masgn-18242.diff added

The parser is currently not setup to handle this, so I don't think it is a bug.  You would have to add new parser rules to allow it, so I would consider this a feature request and not a bug.  Attached is a patch that implements the necessary parser rules, without causing any conflicts.  However, the patch doesn't include the parts needed to make ripper work, as I couldn't figure that out.  @nobu, any chance you could add the necessary code to make ripper work?

----------------------------------------
Feature #18242: Parser makes multiple assignment sad in confusing way
https://bugs.ruby-lang.org/issues/18242#change-94028

* Author: danh337 (Dan H)
* Status: Open
* Priority: Normal
----------------------------------------
Example:
``` ruby
a, b = 2, 1     if 1 < 2     # Works
a, b = [2, 1]   if 1 < 2     # Works
(a, b) = 2, 1   if 1 < 2     # Works
(a, b) = [2, 1] if 1 < 2     # Works
(a, b = [2, 1]) if 1 < 2     # Works
a, b = 2, 1     unless 2 < 1 # Works
a, b = [2, 1]   unless 2 < 1 # Works
(a, b) = 2, 1   unless 2 < 1 # Works
(a, b) = [2, 1] unless 2 < 1 # Works
(a, b = [2, 1]) unless 2 < 1 # Works
1 < 2   and a, b = 2, 1      # SyntaxError
1 < 2   and a, b = [2, 1]    # SyntaxError
1 < 2   and (a, b) = 2, 1    # SyntaxError
1 < 2   and (a, b) = [2, 1]  # SyntaxError
(1 < 2) and a, b = 2, 1      # SyntaxError
(1 < 2) and a, b = [2, 1]    # SyntaxError
(1 < 2) and (a, b) = 2, 1    # SyntaxError
(1 < 2) and (a, b) = [2, 1]  # SyntaxError
1 < 2   and (a, b = 2, 1)    # Works
1 < 2   and (a, b = [2, 1])  # Works
2 < 1   or a, b = 2, 1       # SyntaxError
2 < 1   or a, b = [2, 1]     # SyntaxError
2 < 1   or (a, b) = 2, 1     # SyntaxError
2 < 1   or (a, b) = [2, 1]   # SyntaxError
(2 < 1) or a, b = 2, 1       # SyntaxError
(2 < 1) or a, b = [2, 1]     # SyntaxError
(2 < 1) or (a, b) = 2, 1     # SyntaxError
(2 < 1) or (a, b) = [2, 1]   # SyntaxError
2 < 1   or (a, b = 2, 1)     # Works
2 < 1   or (a, b = [2, 1])   # Works
```
Based on the precedence rules I've been able to find, all of these should work.

Believe it or not, there are cases where using `and` or `or` in a stanza of lines is much more readable.

Should the parser allow all of these? See attached driver script to reproduce this output.

---Files--------------------------------
driver.rb (1.17 KB)
and-or-masgn-18242.diff (963 Bytes)


-- 
https://bugs.ruby-lang.org/

[ruby-core:105581] [Ruby master Feature#18242] Parser makes multiple assignment sad in confusing way

[danh337 (Dan H)]

Issue #18242 has been updated by danh337 (Dan H).


jeremyevans0 (Jeremy Evans) wrote in #note-1:
> [...] Attached is a patch that implements the necessary parser rules, without causing any conflicts.  However, the patch doesn't include the parts needed to make ripper work, as I couldn't figure that out.  @nobu, any chance you could add the necessary code to make ripper work?

@jeremyevans0 you rock. Thanks sir.

----------------------------------------
Feature #18242: Parser makes multiple assignment sad in confusing way
https://bugs.ruby-lang.org/issues/18242#change-94050

* Author: danh337 (Dan H)
* Status: Open
* Priority: Normal
----------------------------------------
Example:
``` ruby
a, b = 2, 1     if 1 < 2     # Works
a, b = [2, 1]   if 1 < 2     # Works
(a, b) = 2, 1   if 1 < 2     # Works
(a, b) = [2, 1] if 1 < 2     # Works
(a, b = [2, 1]) if 1 < 2     # Works
a, b = 2, 1     unless 2 < 1 # Works
a, b = [2, 1]   unless 2 < 1 # Works
(a, b) = 2, 1   unless 2 < 1 # Works
(a, b) = [2, 1] unless 2 < 1 # Works
(a, b = [2, 1]) unless 2 < 1 # Works
1 < 2   and a, b = 2, 1      # SyntaxError
1 < 2   and a, b = [2, 1]    # SyntaxError
1 < 2   and (a, b) = 2, 1    # SyntaxError
1 < 2   and (a, b) = [2, 1]  # SyntaxError
(1 < 2) and a, b = 2, 1      # SyntaxError
(1 < 2) and a, b = [2, 1]    # SyntaxError
(1 < 2) and (a, b) = 2, 1    # SyntaxError
(1 < 2) and (a, b) = [2, 1]  # SyntaxError
1 < 2   and (a, b = 2, 1)    # Works
1 < 2   and (a, b = [2, 1])  # Works
2 < 1   or a, b = 2, 1       # SyntaxError
2 < 1   or a, b = [2, 1]     # SyntaxError
2 < 1   or (a, b) = 2, 1     # SyntaxError
2 < 1   or (a, b) = [2, 1]   # SyntaxError
(2 < 1) or a, b = 2, 1       # SyntaxError
(2 < 1) or a, b = [2, 1]     # SyntaxError
(2 < 1) or (a, b) = 2, 1     # SyntaxError
(2 < 1) or (a, b) = [2, 1]   # SyntaxError
2 < 1   or (a, b = 2, 1)     # Works
2 < 1   or (a, b = [2, 1])   # Works
```
Based on the precedence rules I've been able to find, all of these should work.

Believe it or not, there are cases where using `and` or `or` in a stanza of lines is much more readable.

Should the parser allow all of these? See attached driver script to reproduce this output.

---Files--------------------------------
driver.rb (1.17 KB)
and-or-masgn-18242.diff (963 Bytes)


-- 
https://bugs.ruby-lang.org/

[ruby-core:105592] [Ruby master Feature#18242] Parser makes multiple assignment sad in confusing way

[nobu (Nobuyoshi Nakada)]

Issue #18242 has been updated by nobu (Nobuyoshi Nakada).


That patch seems not including `1 < 2 and a = 1, 2`.

https://github.com/ruby/ruby/pull/4945

----------------------------------------
Feature #18242: Parser makes multiple assignment sad in confusing way
https://bugs.ruby-lang.org/issues/18242#change-94061

* Author: danh337 (Dan H)
* Status: Open
* Priority: Normal
----------------------------------------
Example:
``` ruby
a, b = 2, 1     if 1 < 2     # Works
a, b = [2, 1]   if 1 < 2     # Works
(a, b) = 2, 1   if 1 < 2     # Works
(a, b) = [2, 1] if 1 < 2     # Works
(a, b = [2, 1]) if 1 < 2     # Works
a, b = 2, 1     unless 2 < 1 # Works
a, b = [2, 1]   unless 2 < 1 # Works
(a, b) = 2, 1   unless 2 < 1 # Works
(a, b) = [2, 1] unless 2 < 1 # Works
(a, b = [2, 1]) unless 2 < 1 # Works
1 < 2   and a, b = 2, 1      # SyntaxError
1 < 2   and a, b = [2, 1]    # SyntaxError
1 < 2   and (a, b) = 2, 1    # SyntaxError
1 < 2   and (a, b) = [2, 1]  # SyntaxError
(1 < 2) and a, b = 2, 1      # SyntaxError
(1 < 2) and a, b = [2, 1]    # SyntaxError
(1 < 2) and (a, b) = 2, 1    # SyntaxError
(1 < 2) and (a, b) = [2, 1]  # SyntaxError
1 < 2   and (a, b = 2, 1)    # Works
1 < 2   and (a, b = [2, 1])  # Works
2 < 1   or a, b = 2, 1       # SyntaxError
2 < 1   or a, b = [2, 1]     # SyntaxError
2 < 1   or (a, b) = 2, 1     # SyntaxError
2 < 1   or (a, b) = [2, 1]   # SyntaxError
(2 < 1) or a, b = 2, 1       # SyntaxError
(2 < 1) or a, b = [2, 1]     # SyntaxError
(2 < 1) or (a, b) = 2, 1     # SyntaxError
(2 < 1) or (a, b) = [2, 1]   # SyntaxError
2 < 1   or (a, b = 2, 1)     # Works
2 < 1   or (a, b = [2, 1])   # Works
```
Based on the precedence rules I've been able to find, all of these should work.

Believe it or not, there are cases where using `and` or `or` in a stanza of lines is much more readable.

Should the parser allow all of these? See attached driver script to reproduce this output.

---Files--------------------------------
driver.rb (1.17 KB)
and-or-masgn-18242.diff (963 Bytes)


-- 
https://bugs.ruby-lang.org/

[ruby-core:105608] [Ruby master Feature#18242] Parser makes multiple assignment sad in confusing way

[danh337 (Dan H)]

Issue #18242 has been updated by danh337 (Dan H).


nobu (Nobuyoshi Nakada) wrote in #note-3:
> That patch seems not including `1 < 2 and a = 1, 2`.
> 
> https://github.com/ruby/ruby/pull/4945

Thank you @nobu !

----------------------------------------
Feature #18242: Parser makes multiple assignment sad in confusing way
https://bugs.ruby-lang.org/issues/18242#change-94090

* Author: danh337 (Dan H)
* Status: Open
* Priority: Normal
----------------------------------------
Example:
``` ruby
a, b = 2, 1     if 1 < 2     # Works
a, b = [2, 1]   if 1 < 2     # Works
(a, b) = 2, 1   if 1 < 2     # Works
(a, b) = [2, 1] if 1 < 2     # Works
(a, b = [2, 1]) if 1 < 2     # Works
a, b = 2, 1     unless 2 < 1 # Works
a, b = [2, 1]   unless 2 < 1 # Works
(a, b) = 2, 1   unless 2 < 1 # Works
(a, b) = [2, 1] unless 2 < 1 # Works
(a, b = [2, 1]) unless 2 < 1 # Works
1 < 2   and a, b = 2, 1      # SyntaxError
1 < 2   and a, b = [2, 1]    # SyntaxError
1 < 2   and (a, b) = 2, 1    # SyntaxError
1 < 2   and (a, b) = [2, 1]  # SyntaxError
(1 < 2) and a, b = 2, 1      # SyntaxError
(1 < 2) and a, b = [2, 1]    # SyntaxError
(1 < 2) and (a, b) = 2, 1    # SyntaxError
(1 < 2) and (a, b) = [2, 1]  # SyntaxError
1 < 2   and (a, b = 2, 1)    # Works
1 < 2   and (a, b = [2, 1])  # Works
2 < 1   or a, b = 2, 1       # SyntaxError
2 < 1   or a, b = [2, 1]     # SyntaxError
2 < 1   or (a, b) = 2, 1     # SyntaxError
2 < 1   or (a, b) = [2, 1]   # SyntaxError
(2 < 1) or a, b = 2, 1       # SyntaxError
(2 < 1) or a, b = [2, 1]     # SyntaxError
(2 < 1) or (a, b) = 2, 1     # SyntaxError
(2 < 1) or (a, b) = [2, 1]   # SyntaxError
2 < 1   or (a, b = 2, 1)     # Works
2 < 1   or (a, b = [2, 1])   # Works
```
Based on the precedence rules I've been able to find, all of these should work.

Believe it or not, there are cases where using `and` or `or` in a stanza of lines is much more readable.

Should the parser allow all of these? See attached driver script to reproduce this output.

---Files--------------------------------
driver.rb (1.17 KB)
and-or-masgn-18242.diff (963 Bytes)


-- 
https://bugs.ruby-lang.org/

[ruby-core:105609] [Ruby master Feature#18242] Parser makes multiple assignment sad in confusing way

[danh337 (Dan H)]

Issue #18242 has been updated by danh337 (Dan H).


@nobu I built your PR branch and confirmed that this new parsing works great with the `driver.rb` attached.

Will this patch have to wait for the 3.1.0 release? Sorry I'm not sure how the whole patching and backporting processes work. (But I'm pretty sure it can get complicated.) If these were syntax errors in the past, should the patch be safe for stable versions too?

----------------------------------------
Feature #18242: Parser makes multiple assignment sad in confusing way
https://bugs.ruby-lang.org/issues/18242#change-94097

* Author: danh337 (Dan H)
* Status: Open
* Priority: Normal
----------------------------------------
Example:
``` ruby
a, b = 2, 1     if 1 < 2     # Works
a, b = [2, 1]   if 1 < 2     # Works
(a, b) = 2, 1   if 1 < 2     # Works
(a, b) = [2, 1] if 1 < 2     # Works
(a, b = [2, 1]) if 1 < 2     # Works
a, b = 2, 1     unless 2 < 1 # Works
a, b = [2, 1]   unless 2 < 1 # Works
(a, b) = 2, 1   unless 2 < 1 # Works
(a, b) = [2, 1] unless 2 < 1 # Works
(a, b = [2, 1]) unless 2 < 1 # Works
1 < 2   and a, b = 2, 1      # SyntaxError
1 < 2   and a, b = [2, 1]    # SyntaxError
1 < 2   and (a, b) = 2, 1    # SyntaxError
1 < 2   and (a, b) = [2, 1]  # SyntaxError
(1 < 2) and a, b = 2, 1      # SyntaxError
(1 < 2) and a, b = [2, 1]    # SyntaxError
(1 < 2) and (a, b) = 2, 1    # SyntaxError
(1 < 2) and (a, b) = [2, 1]  # SyntaxError
1 < 2   and (a, b = 2, 1)    # Works
1 < 2   and (a, b = [2, 1])  # Works
2 < 1   or a, b = 2, 1       # SyntaxError
2 < 1   or a, b = [2, 1]     # SyntaxError
2 < 1   or (a, b) = 2, 1     # SyntaxError
2 < 1   or (a, b) = [2, 1]   # SyntaxError
(2 < 1) or a, b = 2, 1       # SyntaxError
(2 < 1) or a, b = [2, 1]     # SyntaxError
(2 < 1) or (a, b) = 2, 1     # SyntaxError
(2 < 1) or (a, b) = [2, 1]   # SyntaxError
2 < 1   or (a, b = 2, 1)     # Works
2 < 1   or (a, b = [2, 1])   # Works
```
Based on the precedence rules I've been able to find, all of these should work.

Believe it or not, there are cases where using `and` or `or` in a stanza of lines is much more readable.

Should the parser allow all of these? See attached driver script to reproduce this output.

---Files--------------------------------
driver.rb (1.17 KB)
and-or-masgn-18242.diff (963 Bytes)


-- 
https://bugs.ruby-lang.org/

[ruby-core:105610] [Ruby master Feature#18242] Parser makes multiple assignment sad in confusing way

[danh337 (Dan H)]

Issue #18242 has been updated by danh337 (Dan H).

File driver.rb added

Attached is an improved driver. Again, every test case works with nobu's branch.

----------------------------------------
Feature #18242: Parser makes multiple assignment sad in confusing way
https://bugs.ruby-lang.org/issues/18242#change-94098

* Author: danh337 (Dan H)
* Status: Open
* Priority: Normal
----------------------------------------
Example:
``` ruby
a, b = 2, 1     if 1 < 2     # Works
a, b = [2, 1]   if 1 < 2     # Works
(a, b) = 2, 1   if 1 < 2     # Works
(a, b) = [2, 1] if 1 < 2     # Works
(a, b = [2, 1]) if 1 < 2     # Works
a, b = 2, 1     unless 2 < 1 # Works
a, b = [2, 1]   unless 2 < 1 # Works
(a, b) = 2, 1   unless 2 < 1 # Works
(a, b) = [2, 1] unless 2 < 1 # Works
(a, b = [2, 1]) unless 2 < 1 # Works
1 < 2   and a, b = 2, 1      # SyntaxError
1 < 2   and a, b = [2, 1]    # SyntaxError
1 < 2   and (a, b) = 2, 1    # SyntaxError
1 < 2   and (a, b) = [2, 1]  # SyntaxError
(1 < 2) and a, b = 2, 1      # SyntaxError
(1 < 2) and a, b = [2, 1]    # SyntaxError
(1 < 2) and (a, b) = 2, 1    # SyntaxError
(1 < 2) and (a, b) = [2, 1]  # SyntaxError
1 < 2   and (a, b = 2, 1)    # Works
1 < 2   and (a, b = [2, 1])  # Works
2 < 1   or a, b = 2, 1       # SyntaxError
2 < 1   or a, b = [2, 1]     # SyntaxError
2 < 1   or (a, b) = 2, 1     # SyntaxError
2 < 1   or (a, b) = [2, 1]   # SyntaxError
(2 < 1) or a, b = 2, 1       # SyntaxError
(2 < 1) or a, b = [2, 1]     # SyntaxError
(2 < 1) or (a, b) = 2, 1     # SyntaxError
(2 < 1) or (a, b) = [2, 1]   # SyntaxError
2 < 1   or (a, b = 2, 1)     # Works
2 < 1   or (a, b = [2, 1])   # Works
```
Based on the precedence rules I've been able to find, all of these should work.

Believe it or not, there are cases where using `and` or `or` in a stanza of lines is much more readable.

Should the parser allow all of these? See attached driver script to reproduce this output.

---Files--------------------------------
driver.rb (1.17 KB)
and-or-masgn-18242.diff (963 Bytes)
driver.rb (2.1 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:105615] [Ruby master Feature#18242] Parser makes multiple assignment sad in confusing way

[nobu (Nobuyoshi Nakada)]

Issue #18242 has been updated by nobu (Nobuyoshi Nakada).


I agree with @jeremyevans0 on that this is not a bug.
Feature requests need the approval by Matz to merge.

----------------------------------------
Feature #18242: Parser makes multiple assignment sad in confusing way
https://bugs.ruby-lang.org/issues/18242#change-94104

* Author: danh337 (Dan H)
* Status: Open
* Priority: Normal
----------------------------------------
Example:
``` ruby
a, b = 2, 1     if 1 < 2     # Works
a, b = [2, 1]   if 1 < 2     # Works
(a, b) = 2, 1   if 1 < 2     # Works
(a, b) = [2, 1] if 1 < 2     # Works
(a, b = [2, 1]) if 1 < 2     # Works
a, b = 2, 1     unless 2 < 1 # Works
a, b = [2, 1]   unless 2 < 1 # Works
(a, b) = 2, 1   unless 2 < 1 # Works
(a, b) = [2, 1] unless 2 < 1 # Works
(a, b = [2, 1]) unless 2 < 1 # Works
1 < 2   and a, b = 2, 1      # SyntaxError
1 < 2   and a, b = [2, 1]    # SyntaxError
1 < 2   and (a, b) = 2, 1    # SyntaxError
1 < 2   and (a, b) = [2, 1]  # SyntaxError
(1 < 2) and a, b = 2, 1      # SyntaxError
(1 < 2) and a, b = [2, 1]    # SyntaxError
(1 < 2) and (a, b) = 2, 1    # SyntaxError
(1 < 2) and (a, b) = [2, 1]  # SyntaxError
1 < 2   and (a, b = 2, 1)    # Works
1 < 2   and (a, b = [2, 1])  # Works
2 < 1   or a, b = 2, 1       # SyntaxError
2 < 1   or a, b = [2, 1]     # SyntaxError
2 < 1   or (a, b) = 2, 1     # SyntaxError
2 < 1   or (a, b) = [2, 1]   # SyntaxError
(2 < 1) or a, b = 2, 1       # SyntaxError
(2 < 1) or a, b = [2, 1]     # SyntaxError
(2 < 1) or (a, b) = 2, 1     # SyntaxError
(2 < 1) or (a, b) = [2, 1]   # SyntaxError
2 < 1   or (a, b = 2, 1)     # Works
2 < 1   or (a, b = [2, 1])   # Works
```
Based on the precedence rules I've been able to find, all of these should work.

Believe it or not, there are cases where using `and` or `or` in a stanza of lines is much more readable.

Should the parser allow all of these? See attached driver script to reproduce this output.

---Files--------------------------------
driver.rb (1.17 KB)
and-or-masgn-18242.diff (963 Bytes)
driver.rb (2.1 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:119530] [Ruby master Feature#18242] Parser makes multiple assignment sad in confusing way

[danh337 (Dan H) via ruby-core]

Issue #18242 has been updated by danh337 (Dan H).


These `and` & `or` operators are good things. They are much more readable for one-liners in some cases.

@matz @nobu I know you are super busy, but is there any way to move this forward?

----------------------------------------
Feature #18242: Parser makes multiple assignment sad in confusing way
https://bugs.ruby-lang.org/issues/18242#change-110144

* Author: danh337 (Dan H)
* Status: Open
----------------------------------------
Example:
``` ruby
a, b = 2, 1     if 1 < 2     # Works
a, b = [2, 1]   if 1 < 2     # Works
(a, b) = 2, 1   if 1 < 2     # Works
(a, b) = [2, 1] if 1 < 2     # Works
(a, b = [2, 1]) if 1 < 2     # Works
a, b = 2, 1     unless 2 < 1 # Works
a, b = [2, 1]   unless 2 < 1 # Works
(a, b) = 2, 1   unless 2 < 1 # Works
(a, b) = [2, 1] unless 2 < 1 # Works
(a, b = [2, 1]) unless 2 < 1 # Works
1 < 2   and a, b = 2, 1      # SyntaxError
1 < 2   and a, b = [2, 1]    # SyntaxError
1 < 2   and (a, b) = 2, 1    # SyntaxError
1 < 2   and (a, b) = [2, 1]  # SyntaxError
(1 < 2) and a, b = 2, 1      # SyntaxError
(1 < 2) and a, b = [2, 1]    # SyntaxError
(1 < 2) and (a, b) = 2, 1    # SyntaxError
(1 < 2) and (a, b) = [2, 1]  # SyntaxError
1 < 2   and (a, b = 2, 1)    # Works
1 < 2   and (a, b = [2, 1])  # Works
2 < 1   or a, b = 2, 1       # SyntaxError
2 < 1   or a, b = [2, 1]     # SyntaxError
2 < 1   or (a, b) = 2, 1     # SyntaxError
2 < 1   or (a, b) = [2, 1]   # SyntaxError
(2 < 1) or a, b = 2, 1       # SyntaxError
(2 < 1) or a, b = [2, 1]     # SyntaxError
(2 < 1) or (a, b) = 2, 1     # SyntaxError
(2 < 1) or (a, b) = [2, 1]   # SyntaxError
2 < 1   or (a, b = 2, 1)     # Works
2 < 1   or (a, b = [2, 1])   # Works
```
Based on the precedence rules I've been able to find, all of these should work.

Believe it or not, there are cases where using `and` or `or` in a stanza of lines is much more readable.

Should the parser allow all of these? See attached driver script to reproduce this output.

---Files--------------------------------
driver.rb (1.17 KB)
and-or-masgn-18242.diff (963 Bytes)
driver.rb (2.1 KB)


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