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Bug #15928

Updated by nobu (Nobuyoshi Nakada) over 1 year ago

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. 

 ```ruby ``` 
 expr::C = rhs lhs 
 ``` 

 The standard seems to be requiring the following evaluation order: 

 1. expr 
   * raise a `TypeError` TypeError if the value is not a kind of `Module` Module 
 2. rhs lhs 
 3. `rb_const_set(expr, rb_const_set(expr, :C, rhs)` lhs) 

 However, the actual implementation evaluates in the following order 

 1. rhs lhs 
 2. expr 
 3. `rb_const_set(expr, rb_const_set(expr, :C, lhs)` lhs) 
   * raise a `TypeError` TypeError if the expr is not a kind of `Module` 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` TypeError but raises a `RuntimeError` 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

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