James Daugherty created GROOVY-12552:
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Summary: STC: property access calls an interface's accessor
instead of the property's own when the property's class is in the same
compilation unit
Key: GROOVY-12552
URL: https://issues.apache.org/jira/browse/GROOVY-12552
Project: Groovy
Issue Type: Bug
Components: Static Type Checker
Affects Versions: 5.1.3
Reporter: James Daugherty
When an interface declares the setter and getter of a property that a class
implements as a Groovy property, static compilation calls the interface's
methods with {{invokeinterface}} when the class is compiled together with the
caller, and the class's own accessors with {{invokevirtual}} when the class is
already compiled. The behaviour at run time is the same, but the same source
compiles to a different class file depending on what else is compiled. Groovy
4.0.33 calls the class's accessors in both cases.
{code:groovy}
interface Named {
void setName(String name)
String getName()
}
abstract class Base implements Named {
String name
}
class Impl extends Base {}
@groovy.transform.CompileStatic
class Svc {
String rename() {
Base base = new Impl()
base.name = 'x' // invokeinterface Named.setName when Base is in
the unit, invokevirtual Impl.setName when it is compiled
base.setName('y')
base.getName()
}
}
{code}
In a real application the interface is often a library one, such as Spring's
{{BeanNameAware}} implemented by a {{beanName}} property.
Reproduced with 5.1.3 and master. A reproducer with a groovyc script and an
incremental Gradle build:
https://github.com/jdaugherty/groovy-property-accessor-interface-method
*Cause*
A property of a class in the compilation unit does not have its accessors yet
when static type checking runs. {{StaticTypeCheckingVisitor.findMethod}} adds a
synthetic accessor for the property when every method found is abstract
(GROOVY-10922), but after the interface's method.
{{StaticTypeCheckingSupport.removeCovariantsAndInterfaceEquivalents}} only
drops an interface method that comes after the method of a class implementing
it, so the interface method stays and is chosen. A compiled class lists its
real accessor first, and the interface method is dropped.
*Proposed fix*
Add the synthetic accessor first, where a compiled class has its accessor, so
that it is preferred over the interface method the same way.
Found while making incremental builds of a Grails application produce the same
classes as a full build; see also GROOVY-12550 and GROOVY-12544.
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