[GROOVY-10320] Generics failed to compile with Groovy 3.0.9 when overriding plus operator

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.9
• Fix Version/s: 4.0.0-beta-1, 3.0.10
• Component/s: Compiler
• Labels: generics
• Environment: $ uname -a ; Linux auo4ever 5.14.13-desktop-1.mga9 #1 SMP Sun Oct 17 09:53:03 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux ; $ java -fullversion ; openjdk full version "11.0.6+9-jvmci-19.3-b07"

Language

groovy

• Assignee: Eric Milles
• Reporter: Adrien Guichard
• Created: 19/Oct/21 16:07
• Updated: 03/Feb/22 22:34
• Resolved: 19/Oct/21 19:12

Description

When compiling with Groovy 3.0.9 the following test-case, I get an error:

$ ./gradlew assemble
[ . . . ]
startup failed:
.../generics-testcase/src/main/groovy/test/GenericsTestCase.groovy: 37: [Static type checking] - Cannot call LC#plus(T) with arguments [LC] 
 @ line 37, column 22.
                   else lineContent += it
                        ^

1 error
[ . . . ]

No errors with previous Groovy compiler.

package test

import groovy.transform.CompileStatic

@CompileStatic
class GenericsTestCase {
    interface ILineContent<T extends ILineContent> {
        T plus(T lineContent)
    }

    @CompileStatic
    private static class LineContent implements ILineContent<LineContent> {
        final BigDecimal sales

        LineContent(final BigDecimal commission) {
            this.sales = sales
        }

        LineContent() {
            this.sales = 0.0
        }

        @Override
        LineContent plus(LineContent lineContent) {
            if (!lineContent) return this
            else new LineContent((sales ?: 0.0) + (lineContent.sales ?: 0.0))
        }
    }

    private static class ClassThatCauseCompilationError<LC extends ILineContent> {
        List<LC> someLines

        LC getTotal() {
            LC lineContent = null
            for (LC it in someLines) {
                if (!lineContent) lineContent = it
                else lineContent += it
            }
            lineContent as LC
        }
    }
}

 

I attached to this report the Gradle test-case to switch quickly between Groovy compiler releases.

 

Thanks for your support,
Adrien