[GROOVY-11154] Script subclasses cannot have constructors with arguments

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 4.0.7
• Component/s: Compiler
• Flags: Patch
• Assignee: Unassigned
• Reporter: jonny
• Created: 14/Aug/23 20:00
• Updated: 21/Aug/23 08:05

Description

Prior to the fix for GROOVY-9857, subclasses of Script could have constructor arguments and still be used (with a little help from InheritConstructors and DefaultGroovyMethods#newInstance).

For example, the following script executes find in Groovy 3.x, but fails after Groovy 4.0.7:

import groovy.transform.InheritConstructors
import org.codehaus.groovy.ast.AnnotationNode
import org.codehaus.groovy.ast.ClassNode
import org.codehaus.groovy.classgen.GeneratorContext
import org.codehaus.groovy.control.CompilationFailedException
import org.codehaus.groovy.control.CompilePhase
import org.codehaus.groovy.control.CompilerConfiguration
import org.codehaus.groovy.control.SourceUnit
import org.codehaus.groovy.control.customizers.CompilationCustomizer
import org.codehaus.groovy.runtime.DefaultGroovyMethods

abstract class NamedScript extends Script {
    NamedScript(String name) {
    }
}

def compilerConfig = new CompilerConfiguration()
compilerConfig.setScriptBaseClass(NamedScript.class.getName())

compilerConfig.addCompilationCustomizers(new CompilationCustomizer(CompilePhase.CONVERSION) {
    @Override
    void call(SourceUnit source, GeneratorContext context, ClassNode classNode) throws CompilationFailedException {
        classNode.addAnnotation(new AnnotationNode(new ClassNode(InheritConstructors.class)))
    }
})

def classLoader = new GroovyClassLoader(new GroovyClassLoader(), compilerConfig)

def parsedClass = classLoader.parseClass('println "Foo"')

DefaultGroovyMethods.newInstance(parsedClass, "dummy").run()

The error returned is:

Implicit super constructor NamedScript() is undefined for generated constructor. Must define an explicit constructor.

Ratpack relies on this behavior for its custom text template renderer.
See how script objects are instantiated in the ScriptEngine#create method.

I talked this out in the Groovy community Slack with blackdrag (see thread), who suggested that we should skip the check for constructors for Script subclasses as a bugfix in Groovy 4, with a potentially breaking change in Groovy 5 to make constructor generation for Script subclasses happen in the same place as any other class.

Issue Links

• is related to: GROOVY-4706 remove special script logic for creating a class node
• is related to: GROOVY-8096 setScriptBaseClass with Java base class breaks @Field initialization from Binding due to generated call to wrong constructor
• is related to: GROOVY-9857 Immutable generates invalid super constructor call