[GROOVY-9726] Compile error needed for illegal field modifier combination

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.5, 2.5.13
• Fix Version/s: 4.0.0-alpha-1, 3.0.6, 2.5.16
• Labels: ClassFormatError
• Assignee: Paul King
• Reporter: Paul King
• Created: 08/Sep/20 00:21
• Updated: 22/May/22 15:59
• Resolved: 09/Sep/20 08:01

Description

The JLS (recent versions at least) states:

It is a compile-time error if a final variable is also declared volatile.

Compiling this class:

public class Foo {
    final volatile String foo = "bar";
}

in Java gives the following compilation error:

error: illegal combination of modifiers: final and volatile

Groovy currently passes compilation but then gives the following error at runtime when trying to create an instance of such a class:

java.lang.ClassFormatError: Illegal field modifiers in class Foo: 0x52

Groovy should also have a compilation error for this case.