[jira] [Comment Edited] (GROOVY-8293) Instanceof inference does work on fields

["Alexey Afanasiev (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/GROOVY-8293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16136609#comment-16136609 ] 

Alexey Afanasiev edited comment on GROOVY-8293 at 8/22/17 10:29 AM:
--------------------------------------------------------------------

_if (str instanceof String)_ should means nothing for compiler in case of field access. It could be easily rewritten in another thread. It's strange for single threaded app too, example:
{code}
import groovy.transform.CompileStatic

@CompileStatic
class Foo {
    Object str = "str"
    def bar() {
        if (str instanceof String) {
            method()
            str.toUpperCase() // here should be compile error
        }
    }
   def method() {
       str = new Object()
   }
}
{code}
Should code above be compiled?


If you say "You're telling it that the type is a String". In code bellow i have assignment, is it not the same? Should this code be compiled(it doesn't compile now)?
{code}
import groovy.transform.CompileStatic

@CompileStatic
class Foo {
    Object str = "str"
    def bar() {
        str = "some str"
        str.toUpperCase() 
    }
}
{code}

My point is compiler couldn't do any type inference correct on fields. At least, there is inconsistency in applying some rules, and ignoring others.


was (Author: alexey afanasiev):
_if (str instanceof String)_ should means nothing for compiler in case of field access. It could be easily rewritten in another thread. It's strange for single threaded app too, example:
{code}
import groovy.transform.CompileStatic

@CompileStatic
class Foo {
    Object str = "str"
    def bar() {
        if (str instanceof String) {
            method()
            str.toUpperCase() // here should be compile error
        }
    }
   def method() {
       str = new Object()
   }
}
{code}
Should code above be compiled?


If you say "You're telling it that the type is a String". In code bellow i have assignment, is it not the same? Should this code be compiled(it doesn't compile now)?
{code}
import groovy.transform.CompileStatic

@CompileStatic
class Foo {
    Object str = "str"
    def bar() {
        str = "some str"
        str.toUpperCase() 
    }
}
{code}

My point is compiler couldn't do any type inference correct on fields. At least, there is inconsistency in applying some rules, and ignoring anothers.

> Instanceof inference does work on fields
> ----------------------------------------
>
>                 Key: GROOVY-8293
>                 URL: https://issues.apache.org/jira/browse/GROOVY-8293
>             Project: Groovy
>          Issue Type: Bug
>          Components: Static compilation, Static Type Checker
>    Affects Versions: 2.4.12
>            Reporter: Alexey Afanasiev
>
> This code should not compile:
> {code}
> import groovy.transform.CompileStatic
> @CompileStatic
> class Foo {
>     Object str = "str"
>     def bar() {
>         if (str instanceof String) {
>             str.toUpperCase() // here should be compile error
>         }
>     }
> }
> {code}
> Documentation http://docs.groovy-lang.org/next/html/documentation/core-semantics.html#type-inference states: 
> _it does not perform any kind of type inference on fields, always falling back to the declared type of a field_



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