[ruby-core:112158] [Ruby master Bug#19392] Endless method vs and/or

Issue #19392 has been updated by nobu (Nobuyoshi Nakada).


zverok (Victor Shepelev) wrote in #note-4:
> Moreover:
> * One-line method definitions aren't any expressions.

It depends on how you define "expressions".
At least in Ruby's terms, any method definition can be an argument of other method calls.

```ruby
public def test1(x) = x = 5
public def test2(x)
  x = 5
end
```

In the above examples, both methods return the method ID and the result will be passed to the method `public`.
To utilize this, `def` returns the ID since 2.3.


----------------------------------------
Bug #19392: Endless method vs and/or
https://bugs.ruby-lang.org/issues/19392#change-101594

* Author: zverok (Victor Shepelev)
* Status: Open
* Priority: Normal
* Backport: 2.7: DONTNEED, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
[Discovered](https://twitter.com/lucianghinda/status/1617783952353406977) by Lucian Ghinda: 

```ruby
def test = puts("foo") and puts("bar")
# prints "bar" immediately
test
# prints "foo"
```

It seems that it is a parser error, right?..
```ruby
RubyVM::AbstractSyntaxTree.parse('def test = puts("foo") and puts("bar")')
#  => 
# (SCOPE@1:0-1:38                                                         
#  tbl: []                                                                
#  args: nil                                                              
#  body:                                                                  
#    (AND@1:0-1:38                                                        
#       (DEFN@1:0-1:22                                                    
#        mid: :test                                                       
#        body:                                                            
#          (SCOPE@1:0-1:22                                                
#           tbl: []                                                       
#           args:                                                         
#             (ARGS@1:0-1:8 pre_num: 0 pre_init: nil opt: nil first_post: nil post_num: 0 post_init: nil rest: nil kw: nil kwrest: nil block: nil)
#           body: (FCALL@1:11-1:22 :puts (LIST@1:16-1:21 (STR@1:16-1:21 "foo") nil))))
#       (FCALL@1:27-1:38 :puts (LIST@1:32-1:37 (STR@1:32-1:37 "bar") nil)))) 
```

E.g. it is parsed as 
```ruby
(def test = puts("foo")) and (puts("bar"))
```
...which is hardly intentional or have any practical use. The rightly parsed code in this case _can_ have practical use, like
```ruby
def write(data) = File.write(@filename, data) == data.size or raise "Something went wrong"
```



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