[GROOVY-9968] @TypeChecked Error: Members of Iterable<T extends Foo> are Foo, not Object

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.7
• Fix Version/s: 3.0.8, 4.0.0-alpha-3, 2.5.17
• Component/s: Compiler
• Environment: Windows 10 ; jdk-11.0.10.9-hotspot ; IntelliJ 2020.3.2
• Assignee: Eric Milles
• Reporter: mgroovy
• Created: 05/Mar/21 16:49
• Updated: 19/Dec/22 14:38
• Resolved: 07/Mar/21 02:37

Description

Problem
Trying to build the sample test code below fails with:

Groovyc: [Static type checking] - No such property: name for class: java.lang.Object
Groovyc: Expected parameter of type java.lang.Object but got simple.groovy.bugs.groovy3.gb_2021_03_05.iterable_t_extends.Foo
Groovyc: [Static type checking] - No such property: name for class: java.lang.Object

If we do not explicitly give the member type of the IterableTExtendsFoo iterable, Groovy assumes that the type is Object, even though it has been defined as being a subclass of Foo in the definition of IterableTExtendsFoo<T extends Foo>.

Expected

• Code should compile.
• If Groovy could not deduce that IterableTExtendsFoo has been initialized with a List<T extends Foo>, then it should reject the line where the IterableTExtendsFoo ctor is called.
• Note: Works as expected in Groovy 2.5.x (at least up to 2.5.14)

Sample Code

import groovy.transform.TypeChecked
import org.junit.Ignore
import org.junit.Test

@TypeChecked
class Groovy3_Iterable_T_extends_Bug {
	@Test
	@Ignore
	void 'Groovy 3-0-7 Members of Iterable T extends Foo are Foo'() {
		// Compiler should reject the following line if the ctor arg would not of type List<T extends Foo>
		final iterableTExtendsFoo = new IterableTExtendsFoo([new Foo('Sli'),new Foo('Msha'),new Foo('Dy'),])
		//final iterableTExtendsFoo = new IterableTExtendsFoo<Foo>([new Foo('Sli'),new Foo('Msha'),new Foo('Dy'),]) // Explicitly giving the iterable member type makes the code compile
		println iterableTExtendsFoo.collect { "Hi, my name is: $it.name" }
		println iterableTExtendsFoo.collect { Foo f -> "name=$f.name" }
	}
}

@Canonical class Foo { String name }

@Canonical
class IterableTExtendsFoo<T extends Foo> implements Iterable<T> {
	List<T> foos
	@Override Iterator<T> iterator() { foos.iterator() }
}

Issue Links

• relates to: GROOVY-10619 STC: fix support for unbounded wildcard references to self-bounded type parameters