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https://issues.apache.org/jira/browse/GROOVY-12603?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Scott Murphy Heiberg updated GROOVY-12603:
------------------------------------------
Description:
{code:groovy}
trait T {
private int x = 1
def m() { [1].each { x++ }; [1].each { x += 2 }; x }
}
class C implements T {}
new C().m()
{code}
Actual: m() returns 1 because both updates are lost. With @CompileStatic on the
trait, the += throws GroovyCastException: Cannot cast object '3' with class
'java.lang.Integer' to class 'T'. For a static field, or inside a lambda,
@CompileStatic fails at compile time instead ("Cannot access method: T__x$get()
of class: java.lang.Object", or an ASM instruction selection error). The same
applies to public and static fields, x--, ++x, and the other compound operators.
Expected: x += 2 and the other compound operators update the field, as they do
in a trait method body. x++, x--, ++x and --x are rejected at compile time with
"Postfix/Prefix expressions on trait fields/properties are not supported in
traits", as they are in a trait method body.
Cause: the trait transformation rewrites x op= y into x = x op y and rejects
prefix and postfix operations on trait fields, but that rewriter never visited
closure or lambda bodies. The field reference inside the closure was turned
into a field-helper getter call, and the operator was applied to the call
result.
Seen in 4.0.33, 5.0.8 and 6.0.0.
PR: https://github.com/apache/groovy/pull/3130
was:
{code:groovy}
trait T {
private int x = 1
def m() { [1].each { x++ }; [1].each { x += 2 }; x }
}
class C implements T {}
new C().m()
{code}
Actual: m() returns 1 because both updates are lost. With @CompileStatic on the
trait, the += throws GroovyCastException: Cannot cast object '3' with class
'java.lang.Integer' to class 'T'. For a static field, or inside a lambda,
@CompileStatic fails at compile time instead ("Cannot access method: T__x$get()
of class: java.lang.Object", or an ASM instruction selection error). The same
applies to public and static fields, x--, ++x, and the other compound operators.
Expected: x += 2 and the other compound operators update the field, as they do
in a trait method body. x++, x--, ++x and --x are rejected at compile time with
"Postfix/Prefix expressions on trait fields/properties are not supported in
traits", as they are in a trait method body.
Cause: the trait transformation rewrites x op= y into x = x op y and rejects
prefix and postfix operations on trait fields, but that rewriter never visited
closure or lambda bodies. The field reference inside the closure was turned
into a field-helper getter call, and the operator was applied to the call
result.
Seen in 4.0.33, 5.0.8 and 6.0.0.
> Compound assignment, increment or decrement of a trait field inside a closure
> or lambda loses the update or fails
> -----------------------------------------------------------------------------------------------------------------
>
> Key: GROOVY-12603
> URL: https://issues.apache.org/jira/browse/GROOVY-12603
> Project: Groovy
> Issue Type: Bug
> Affects Versions: 4.0.33, 5.0.8, 6.0.0
> Reporter: Scott Murphy Heiberg
> Priority: Major
>
> {code:groovy}
> trait T {
> private int x = 1
> def m() { [1].each { x++ }; [1].each { x += 2 }; x }
> }
> class C implements T {}
> new C().m()
> {code}
> Actual: m() returns 1 because both updates are lost. With @CompileStatic on
> the trait, the += throws GroovyCastException: Cannot cast object '3' with
> class 'java.lang.Integer' to class 'T'. For a static field, or inside a
> lambda, @CompileStatic fails at compile time instead ("Cannot access method:
> T__x$get() of class: java.lang.Object", or an ASM instruction selection
> error). The same applies to public and static fields, x--, ++x, and the other
> compound operators.
> Expected: x += 2 and the other compound operators update the field, as they
> do in a trait method body. x++, x--, ++x and --x are rejected at compile time
> with "Postfix/Prefix expressions on trait fields/properties are not supported
> in traits", as they are in a trait method body.
> Cause: the trait transformation rewrites x op= y into x = x op y and rejects
> prefix and postfix operations on trait fields, but that rewriter never
> visited closure or lambda bodies. The field reference inside the closure was
> turned into a field-helper getter call, and the operator was applied to the
> call result.
> Seen in 4.0.33, 5.0.8 and 6.0.0.
> PR: https://github.com/apache/groovy/pull/3130
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