This is related to JDK-8210483, JDK-8203679.

```
import java.util.Optional;
import java.util.stream.Stream;

abstract class T {

  abstract void f(long c); 

  interface I { 
    I g(String o); 
  }

  private void test(Stream<I> is, Optional<String> o) {
    f(  
        is.map(
                i -> {
                  o.ifPresent(i::g);
                  return null;
                })  
            .count());
  }
}
```

```
An exception has occurred in the compiler (12-ea). Please file a bug against the Java compiler via the Java bug reporting page (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com) for duplicates. Include your program and the following diagnostic in your report. Thank you.
java.lang.AssertionError
        at jdk.compiler/com.sun.tools.javac.util.Assert.error(Assert.java:155)
        at jdk.compiler/com.sun.tools.javac.util.Assert.check(Assert.java:46)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr$2$1.setOverloadKind(DeferredAttr.java:175)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.visitReference(ArgumentAttr.java:284)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMemberReference.accept(JCTree.java:2264)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.attribArg(ArgumentAttr.java:199)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:662)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribArgs(Attr.java:764)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitApply(Attr.java:2185)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1707)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:664)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribExpr(Attr.java:715)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitExec(Attr.java:1863)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1517)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:664)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:737)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStats(Attr.java:756)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:1307)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1026)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:664)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:737)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStats(Attr.java:756)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:1307)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1026)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:664)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr.attribSpeculative(DeferredAttr.java:501)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr.attribSpeculative(DeferredAttr.java:484)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr.attribSpeculativeLambda(DeferredAttr.java:459)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr$DeferredAttrNode$StructuralStuckChecker.canLambdaBodyCompleteNormally(DeferredAttr.java:903)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr$DeferredAttrNode$StructuralStuckChecker.visitLambda(DeferredAttr.java:881)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCLambda.accept(JCTree.java:1880)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr$DeferredAttrNode$StructuralStuckChecker.complete(DeferredAttr.java:835)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr$DeferredType.check(DeferredAttr.java:338)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr$DeferredAttrNode.process(DeferredAttr.java:782)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr$DeferredAttrContext.complete(DeferredAttr.java:629)
        at jdk.compiler/com.sun.tools.javac.comp.Infer.instantiateMethod(Infer.java:214)
        at jdk.compiler/com.sun.tools.javac.comp.Resolve.rawInstantiate(Resolve.java:603)
        at jdk.compiler/com.sun.tools.javac.comp.Resolve.selectBest(Resolve.java:1561)
        at jdk.compiler/com.sun.tools.javac.comp.Resolve.findMethodInScope(Resolve.java:1731)
```