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Bug 362285

Summary:	[xbase][types] problem with type inference of closure return type
Product:	[Modeling] TMF	Reporter:	Knut Wannheden <knut.wannheden>
Component:	Xtext	Assignee:	Project Inbox <tmf.xtext-inbox>
Status:	CLOSED FIXED	QA Contact:
Severity:	normal
Priority:	P3	Flags:	knut.wannheden: kepler+
Version:	2.1.0
Target Milestone:	M6
Hardware:	PC
OS:	Mac OS X - Carbon (unsup.)
Whiteboard:

Description Knut Wannheden

2011-10-28 05:06:21 EDT

For the following Xtend2 file:

public class Foo<T> {
	def foo() {
		[T x|x].apply(null)
	}	
}

an error marker is generated for the closure body expression "x": "Incompatible implicit return type. Expected T but was Result". I don't think there should be an error marker in this case.

Workarounds. Change the code to read:

public class Foo<T> {
	def foo() {
		[T x|x as T].apply(null)
	}	
}

or:

public class Foo<T> {
	def T foo() {
		[T x|x].apply(null)
	}	
}

Comment 1 Knut Wannheden

2011-10-28 05:08:20 EDT

I was further surprised to find that the example works if the generic type is declared on the method instead:

public class Foo {
	def <T> foo() {
		[T x|x].apply(null)
	}
}

Comment 2 Knut Wannheden

2013-02-16 09:04:15 EST

This bug has been fixed in Xtend 2.4.