FULL PRODUCT VERSION :
java version "1.8.0_40"
Java(TM) SE Runtime Environment (build 1.8.0_40-b26)
Java HotSpot(TM) 64-Bit Server VM (build 25.40-b25, mixed mode)

A DESCRIPTION OF THE PROBLEM :
The following works with 1.8.0_11 and the Eclipse Java compiler:

public class Bug {
public static void main(String[] args) {
foo(bar(true, b -> b ? 1 : 0));
}

public static void foo(int... baz) { }

public static <R, A> R bar(A arg, java.util.function.Function<A, R> f) {
return f.apply(arg);
}
}

1.8.0_40 error message:

Bug.java:3: error: incompatible types: inferred type does not conform to upper bound(s)
                foo(bar(true, b -> b ? 1 : 0));
                       ^
    inferred: Integer
    upper bound(s): int[],Object
Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output
1 error

REGRESSION. Last worked in version 8u11


REPRODUCIBILITY :
This bug can be reproduced always.