[ruby-core:93187] [Ruby trunk Bug#15928] Constant declaration does not conform to JIS 3017:2013
From:
mame@...
Date:
2019-06-16 14:37:06 UTC
List:
ruby-core #93187
Issue #15928 has been updated by mame (Yusuke Endoh).
IMO, for `expr::C = lhs`, it should first evaluate `expr` and then do `lhs` because `expr` is left to `lhs`. But I'm unsure whether it should raise a TypeError when `expr` is not a Module. My personal expectation is that `lhs` is evaluated and then a TypeError is raised.
Anyway, the change will bring incompatibility. We need to consider whether it is worth fixing at the cost of incompatibility issues.
----------------------------------------
Bug #15928: Constant declaration does not conform to JIS 3017:2013
https://bugs.ruby-lang.org/issues/15928#change-78627
* Author: yugui (Yuki Sonoda)
* Status: Open
* Priority: Normal
* Assignee:
* Target version:
* ruby -v: ruby 2.7.0dev (2019-06-16T14:01:46Z master d4929f5185) [x86_64-darwin18]
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
The order of evaluation in constant declaration does not conform to JIS 3017:2013 11.4.2.2.3.
# Problem
Suppose that we are evaluating the following program.
```
expr::C = lhs
```
The standard seems to be requiring the following evaluation order:
1. expr
* raise a TypeError if the value is not a kind of Module
2. lhs
3. rb_const_set(expr, :C, lhs)
However, the actual implementation evaluates in the following order
1. lhs
2. expr
3. rb_const_set(expr, :C, lhs)
* raise a TypeError if the expr is not a kind of Module
# How to reproduce
The next program does not raise "recv" but raises "value"
```
raise("recv")::C = raise("value")
```
The next program does not raise a TypeError but raises a RuntimeError
```
A = 1
A::C = raise("value")
```
# Question
* Is this interpretation of the standard correct?
* If it is, Should we change the current behavior?
* If we shouldn't, does it mean an issue in the standard?
c.f.
* https://twitter.com/n0kada/status/1140234416175763456
--
https://bugs.ruby-lang.org/
Unsubscribe: <mailto:[email protected]?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>