Internal error with super method call

[ochafik]

The following code compiled with --language_in=ECMASCRIPT6_STRICT -O SIMPLE:

class Foo {
  m() {}
}
class Bar extends Foo {
  m() {
    super.m(); // `super['m']()` also crashes
  }
}

Crashes with the following trace:

INTERNAL COMPILER ERROR.
Please report this problem.

Unexpected variable arguments
  Node(NAME arguments): bug_closure.js:5:0
class Bar extends Foo {
  Parent(CALL): bug_closure.js:5:0
class Bar extends Foo {

    at com.google.javascript.jscomp.VarCheck.visit(VarCheck.java:202)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:609)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:603)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:603)
    at com.google.javascript.jscomp.NodeTraversal.traverseBlockScope(NodeTraversal.java:652)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:597)
    at com.google.javascript.jscomp.NodeTraversal.traverseFunction(NodeTraversal.java:643)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:595)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:603)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:603)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:603)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:603)
    at com.google.javascript.jscomp.NodeTraversal.traverseRoots(NodeTraversal.java:314)
    at com.google.javascript.jscomp.VarCheck.process(VarCheck.java:142)
    at com.google.javascript.jscomp.PhaseOptimizer$NamedPass.process(PhaseOptimizer.java:285)

[concavelenz]

The ES6 to ES6 complication is still experimental, please use --language_out=ECMASCRIPT5_STRICT for the time being.

[ochafik]

The ES6 to ES6 compilation is still experimental, please use --language_out=ECMASCRIPT5_STRICT for the time being.

Will do, thanks, but doesn't fix this crash unfortunately.

[MatrixFrog]

I'm actually seeing this for an even simpler case:

class Foo {}
class Bar extends Foo {}

Maybe something to do with one of the recent changes from NodeTraversal.traverse to NodeTraversal.traverseEs6

[MatrixFrog]

git bisect says 3043356 is to blame.

[MatrixFrog]

So it seems to be failing on the synthetic constructor that is inserted by the compiler, which looks like

class Bar extends Foo {
  constructor() {
    Foo.apply(this, arguments);
  }
}

But if you add that constructor explicitly then it doesn't fail. What's strange is, it's crashing in the second checkVars pass (the "sanity check" that happens at the end) not the one that was moved in 3043356.

[ochafik]

Yay, thanks guys!