[GROOVY-6263] Accessing private methods from public ones using categories and inheritance causes MissingMethodException

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.8.9, 2.0.8, 2.1.6, 2.4.0-rc-1
• Fix Version/s: 2.5.0-alpha-1
• Component/s: groovy-runtime
• Labels: breaking
• Assignee: Jochen Theodorou
• Reporter: Dinko Srkoc
• Created: 16/Jul/13 11:05
• Updated: 02/May/17 02:03
• Resolved: 19/Mar/15 05:43

Description

Private methods cannot be accessed from public ones when categories are used, and inheritance is involved.

Consider this code:

class A {
    private foo(a) { 1 }
    def baz() { foo() }
}

class B extends A {}

class C {}

use(C) {
    new B().baz()
}

Calling baz() fails with the MissingMethodException. Here is the error message and the partial stacktrace:

groovy.lang.MissingMethodException: No signature of method: B.foo() is applicable for argument types: () values: []
Possible solutions: baz(), any(), find(), use([Ljava.lang.Object;), find(groovy.lang.Closure), is(java.lang.Object)
	at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:55)
	at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:78)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:49)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:133)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:137)
	at A.baz(ConsoleScript0:3)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
	at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1085)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:909)
	at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:39)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:112)
	at ConsoleScript0$_run_closure1.doCall(ConsoleScript0:11)
	at ConsoleScript0$_run_closure1.doCall(ConsoleScript0)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
	at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
	at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:272)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:909)
	at groovy.lang.Closure.call(Closure.java:411)
	at groovy.lang.Closure.call(Closure.java:405)
	at org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.use(GroovyCategorySupport.java:109)
	at org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.access$400(GroovyCategorySupport.java:65)
	at org.codehaus.groovy.runtime.GroovyCategorySupport.use(GroovyCategorySupport.java:249)
	at org.codehaus.groovy.runtime.DefaultGroovyMethods.use(DefaultGroovyMethods.java:385)
	at org.codehaus.groovy.runtime.dgm$594.invoke(Unknown Source)
	at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoMetaMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:313)
	at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:52)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:49)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:133)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:145)
	at ConsoleScript0.run(ConsoleScript0:10)
...

Without using categories, everything is fine:

//use(C) {
    assert new B().baz() == 1
//}

as is without inheritance:

use(C) {
    assert new A().baz() == 1
}

Not using private modifier also helps:

class A {
    protected foo(a) { 1 }
    def baz() { foo() }
}

class B extends A {}

class C {}

use(C) {
    assert new B().baz() == 1
}