[GROOVY-10955] @Builder doesn't work on records

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.0.10
• Assignee: Paul King
• Reporter: Paul King
• Created: 28/Feb/23 15:38
• Updated: 13/Mar/23 12:15
• Resolved: 08/Mar/23 12:13

Description

For this code:

import groovy.transform.builder.*
@Builder
record Developer(Integer id, String first, String last, String email, List<String> skills) { }
Developer.builder().id(2).build()

The code fails in the build method. It is meant to create a new Developer but instead creates a DeveloperBuilder instance and then throws a cast exception:

org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object 'Developer$DeveloperBuilder@5ef26266' with class 'Developer$DeveloperBuilder' to class 'Developer'
        ...
	at Developer$DeveloperBuilder.build(ConsoleScript25)

I wasn't necessarily expecting it to work. It could be made to work or we could explicitly disable it for records.

Similarly, this code fails:

@Builder(builderStrategy=InitializerStrategy)
record Developer(Integer id, String first, String last, String email, List<String> skills) { }
Developer.createInitializer().id(2).build()

with this more obscure error:

java.lang.ArrayIndexOutOfBoundsException: Internal compiler error while compiling ConsoleScript26
Method: org.codehaus.groovy.ast.MethodNode@7cd420f9[Developer$DeveloperInitializer id(java.lang.Integer) from Developer$DeveloperInitializer]
Line -1, expecting casting to Developer$DeveloperInitializer<groovy.transform.builder.InitializerStrategy$SET, T1, T2, T3, T4> but operand stack is empty
        ...
	at org.codehaus.groovy.classgen.asm.OperandStack.doConvertAndCast(OperandStack.java:340)
	at org.codehaus.groovy.classgen.asm.StatementWriter.writeReturn(StatementWriter.java:593)
	at org.codehaus.groovy.classgen.AsmClassGenerator.visitReturnStatement(AsmClassGenerator.java:822)
...

I would probably just used the named args style rather than a builder, e.g.:

var dev1 = new Developer(id: 1, first: 'Dan', last: 'Vega', email: '[e-mail]', skills: ['Java', 'Spring'])
assert dev1.with{ [id, first, last, email, skills] } ==
//  [1, 'Dan', 'Vega', '[e-mail]', ['Java', 'Spring']]

But we should either support or disable one or more of the @Builder strategies.

Builder can also be written on constructors. That does work for the default strategy but again not for the InitializerStrategy. Here is a working example:

import groovy.transform.builder.*
record Developer(Integer id, String first, String last, String email, List<String> skills) {
    @Builder
    Developer(Integer id, String full, String email, List<String> skills) {
        this(id, full.split(' ')[0], full.split(' ')[1], email, skills)
    }
}

var dev1 = new Developer(id: 1, first: 'Dan', last: 'Vega', email: '[e-mail]', skills: ['Java', 'Spring'])

assert dev1.with{ [id, first, last, email, skills] } ==
  [1, 'Dan', 'Vega', '[e-mail]', ['Java', 'Spring']]

var dev2 = Developer.builder().id(2).full('Paul King').email('[e-mail]').skills(['Java', 'Groovy']).build()

assert dev2.with{ [id, first, last, email, skills] } ==
  [2, 'Paul', 'King', '[e-mail]', ['Java', 'Groovy']]

Issue Links

• links to: GitHub Pull Request #1868