Tue, 14 May 2013 11:11:09 -0700
8012556: Implement lambda methods on interfaces as static
8006140: Javac NPE compiling Lambda expression on initialization expression of static field in interface
Summary: Lambdas occurring in static contexts or those not needing instance information should be generated into static methods. This has long been the case for classes. However, as a work-around to the lack of support for statics on interfaces, interface lambda methods have been generated into default methods. For lambdas in interface static contexts (fields and static methods) this causes an NPE in javac because there is no 'this'. MethodHandles now support static methods on interfaces. This changeset allows lambda methods to be generated as static interface methods. An existing bug in Hotspot (8013875) is exposed in a test when the "-esa" flag is used. This test and another test that already exposed this bug have been marked with @ignore.
Reviewed-by: mcimadamore
1 /*
2 * @test /nodynamiccopyright/
3 * @bug 8009131
4 * @summary Overload: javac should discard methods that lead to errors in lambdas with implicit parameter types
5 * @compile/fail/ref=TargetType66.out -XDrawDiagnostics TargetType66.java
6 */
7 class TargetType66 {
8 interface SAM1 {
9 void m(String s);
10 }
12 interface SAM2 {
13 void m(Integer s);
14 }
16 void g(SAM1 s1) { }
17 void g(SAM2 s2) { }
19 void test() {
20 g(x->{ String s = x; }); //g(SAM1)
21 g(x->{ Integer i = x; }); //g(SAM2)
22 g(x->{ Object o = x; }); //ambiguous
23 g(x->{ Character c = x; }); //error: inapplicable methods
24 g(x->{ Character c = ""; }); //error: incompatible types
25 }
26 }