FULL PRODUCT VERSION :
java version "1.8.0_20"
Java(TM) SE Runtime Environment (build 1.8.0_20-b26)
Java HotSpot(TM) 64-Bit Server VM (build 25.20-b23, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Ubuntu 13.04 

A DESCRIPTION OF THE PROBLEM :
This is a bug report for re-opening https://bugs.openjdk.java.net/browse/JDK-8044546 that has been closed although the issue is obviously still not fixed in JDK 1.8.20.

The testcase I added to reproduce the issue was provided by Vicente Arturo Romero Zaldivar and can be found in the comments of the issue mentioned above.

REGRESSION.  Last worked in version 8u11

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Try to compile the following code:

abstract class Test {
    boolean foo() {
        return bar(true, a -> {});
    }

    abstract <T1> T1 bar(T1 t1, S<T1> s);
}

interface S<S1> {
    void baz(S1 s1);
} 

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Code should compile without any exceptions in the compiler
ACTUAL -
Compilation fails with a NPE in the compiler

ERROR MESSAGES/STACK TRACES THAT OCCUR :
An exception has occurred in the compiler (1.8.0_20). Please file a bug at the Java Developer Connection (http://java.sun.com/webapps/bugreport)  after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report.  Thank you.
java.lang.NullPointerException
        at com.sun.tools.javac.code.Types.isConvertible(Types.java:290)
        at com.sun.tools.javac.comp.Check.assertConvertible(Check.java:922)
        at com.sun.tools.javac.comp.Check.checkMethod(Check.java:876)
        at com.sun.tools.javac.comp.Attr.checkMethod(Attr.java:3838)
        at com.sun.tools.javac.comp.Attr.checkIdInternal(Attr.java:3615)
        at com.sun.tools.javac.comp.Attr.checkMethodIdInternal(Attr.java:3522)
        at com.sun.tools.javac.comp.Attr.checkMethodId(Attr.java:3501)
        at com.sun.tools.javac.comp.Attr.checkId(Attr.java:3488)
        at com.sun.tools.javac.comp.Attr.visitIdent(Attr.java:3237)
        at com.sun.tools.javac.tree.JCTree$JCIdent.accept(JCTree.java:2011)
        at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
        at com.sun.tools.javac.comp.Attr.visitApply(Attr.java:1843)
        at com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1465)
        at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
        at com.sun.tools.javac.comp.Attr.visitReturn(Attr.java:1704)
        at com.sun.tools.javac.tree.JCTree$JCReturn.accept(JCTree.java:1384)
        at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
        at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:676)
        at com.sun.tools.javac.comp.Attr.attribStats(Attr.java:692)
        at com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:1142)
        at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:909)
        at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
        at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:676)
        at com.sun.tools.javac.comp.Attr.visitMethodDef(Attr.java:1035)
        at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:778)
        at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
        at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:676)
        at com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:4342)
        at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4252)
        at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4181)
        at com.sun.tools.javac.comp.Attr.attrib(Attr.java:4156)
        at com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1248)
        at com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:901)
        at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:860)
        at com.sun.tools.javac.main.Main.compile(Main.java:523)
        at com.sun.tools.javac.main.Main.compile(Main.java:381)
        at com.sun.tools.javac.main.Main.compile(Main.java:370)
        at com.sun.tools.javac.main.Main.compile(Main.java:361)
        at com.sun.tools.javac.Main.compile(Main.java:56)
        at com.sun.tools.javac.Main.main(Main.java:42)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
abstract class Test {
    boolean foo() {
        return bar(true, a -> {});
    }

    abstract <T1> T1 bar(T1 t1, S<T1> s);
}

interface S<S1> {
    void baz(S1 s1);
} 
---------- END SOURCE ----------