From: "Hanmac (Hans Mackowiak) via ruby-core" <ruby-core@...>
Date: 2023-04-06T07:23:29+00:00
Subject: [ruby-core:113148] [Ruby master Bug#19583] Unary minus inconsistency when used with variables and literals

Issue #19583 has been updated by Hanmac (Hans Mackowiak).


`-2` is a literal
`- 2` is a function call of `-@`

and -@ doesn't have preference over function call, see this:

```ruby
a = 2
v = -a.to_s
p v #=> 2
```


----------------------------------------
Bug #19583: Unary minus inconsistency when used with variables and literals
https://bugs.ruby-lang.org/issues/19583#change-102683

* Author: hurricup (Alexandr Evstigneev)
* Status: Open
* Priority: Normal
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
This feels a bit inconsistent and I could not find an explanation.

This is fine and `-` has higher precedence than `.`
```
-2.upto 0 do |arg|
puts arg
end
```

But this is not working, won't even compile (requires parens):
```
var = 2
-var.upto 0 do |arg|
puts arg
end
```

I presume that in the first example there is no unary minus operation, just negative literal. 

Ok, according to this - my assumption is correct. The question is - why?
```
def some
  puts -2
  a = 42
  puts -a
end

puts RubyVM::InstructionSequence.of(method :some).disasm
```



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