This crash bisects to JDK-8262891: earlier versions accept this code as valid, after that commit it causes an NPE.

The Lint.augment stack trace is similar to JDK-8181464, where mcimadamore noted:

> this problem of javac crashing because of a 'null' Lint happens very frequently - and in cases where, if attribution could run its course, a regular error message would be displayed. So perhaps it's time we address this by having a 'dummy' Lint object which doesn't do anything instead of 'null' - that would let execution flow even in exceptional cases like this one.

Repro:

===
import java.util.Collection;
import java.util.function.Function;
import java.util.function.Supplier;

abstract class T {

  abstract <T> T r(Function<String, Supplier<T>> x);

  enum E {
    ONE
  }

  abstract <T> Supplier<T> f(Function<T, Supplier<T>> x);

  public void updateAcl(E e, Supplier<Void> v) {
    r(
        (String t) -> {
          switch (e) {
            case ONE:
              return f(
                  a -> {
                    Collection<String> m = null;
                    return v;
                  });
            default:
              return v;
          }
        });
  }
}
===

$ javac T.java
java.lang.NullPointerException: Cannot invoke "com.sun.tools.javac.code.Symbol.getDeclarationAttributes()" because "sym" is null
        at jdk.compiler/com.sun.tools.javac.code.Lint.augment(Lint.java:75)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AliveAnalyzer.visitVarDef(Flow.java:595)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:1028)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:445)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AliveAnalyzer.scanStat(Flow.java:505)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AliveAnalyzer.scanStats(Flow.java:513)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AliveAnalyzer.visitBlock(Flow.java:605)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1092)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:445)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AliveAnalyzer.scanStat(Flow.java:505)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AliveAnalyzer.visitLambda(Flow.java:879)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCLambda.accept(JCTree.java:1975)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:445)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:57)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AliveAnalyzer.visitApply(Flow.java:856)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1798)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:445)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AliveAnalyzer.visitReturn(Flow.java:845)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCReturn.accept(JCTree.java:1710)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:445)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:57)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.visitCase(TreeScanner.java:181)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCCase.accept(JCTree.java:1336)
        at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:445)
        at jdk.compiler/com.sun.tools.javac.comp.Flow$AliveAnalyzer.analyzeTree(Flow.java:907)
        at jdk.compiler/com.sun.tools.javac.comp.Flow.aliveAfter(Flow.java:274)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.handleSwitch(Attr.java:1794)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitSwitch(Attr.java:1580)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCSwitch.accept(JCTree.java:1295)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:668)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:742)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStats(Attr.java:761)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:1439)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1092)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:668)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:742)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStats(Attr.java:761)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:1439)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1092)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.visitTree(ArgumentAttr.java:207)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$Visitor.visitBlock(JCTree.java:3413)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1092)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.attribArg(ArgumentAttr.java:197)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:666)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr.attribSpeculative(DeferredAttr.java:500)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr.attribSpeculative(DeferredAttr.java:480)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr.attribSpeculative(DeferredAttr.java:467)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr.attribSpeculativeLambda(DeferredAttr.java:442)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.lambda$visitLambda$4(ArgumentAttr.java:301)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.processArg(ArgumentAttr.java:242)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.visitLambda(ArgumentAttr.java:299)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCLambda.accept(JCTree.java:1975)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.attribArg(ArgumentAttr.java:197)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:666)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribArgs(Attr.java:769)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitApply(Attr.java:2554)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1798)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:668)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribExpr(Attr.java:721)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitExec(Attr.java:2272)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1585)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:668)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:742)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStats(Attr.java:761)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:1439)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1092)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:668)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:742)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitMethodDef(Attr.java:1229)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:922)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:668)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:742)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:5478)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribClass(Attr.java:5369)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribClass(Attr.java:5200)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attrib(Attr.java:5145)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1317)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:946)
        at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:317)
        at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:176)
        at jdk.compiler/com.sun.tools.javac.Main.compile(Main.java:64)
        at jdk.compiler/com.sun.tools.javac.Main.main(Main.java:50)