Closure internal error on '[].slice.call(arguments)'

[juj]

From https://stackoverflow.com/a/960870 I randomly stumbled to using [].slice.call(arguments) to convert the old arguments object to an array (for use in scenarios where ES6 constructs are not allowed).

Though then got to see Closure compiler croak in that construct:

null
  Node(NAME arguments): C:/Users/clb/AppData/Local/Temp/emscripten_temp_9jd6b43i/a.out.jso1.js:158:31
      var args = [].slice.call(arguments);
  Parent(CALL): C:/Users/clb/AppData/Local/Temp/emscripten_temp_9jd6b43i/a.out.jso1.js:158:17
      var args = [].slice.call(arguments);

        at com.google.javascript.jscomp.Compiler.throwInternalError(Compiler.java:3282)
        at com.google.javascript.jscomp.NodeTraversal.throwUnexpectedException(NodeTraversal.java:516)
        at com.google.javascript.jscomp.NodeTraversal.traverse(NodeTraversal.java:536)
        at com.google.javascript.jscomp.NodeTraversal$Builder.traverse(NodeTraversal.java:472)
        at com.google.javascript.jscomp.NodeTraversal.traverse(NodeTraversal.java:542)
        at com.google.javascript.jscomp.OptimizeArgumentsArray.process(OptimizeArgumentsArray.java:98)
        at com.google.javascript.jscomp.PhaseOptimizer$NamedPass.process(PhaseOptimizer.java:240)
        at com.google.javascript.jscomp.PhaseOptimizer.process(PhaseOptimizer.java:179)
        at com.google.javascript.jscomp.Compiler.performTranspilationAndOptimizations(Compiler.java:2968)
        at com.google.javascript.jscomp.Compiler.lambda$stage2Passes$7(Compiler.java:1025)
        at com.google.javascript.jscomp.CompilerExecutor.lambda$runInCompilerThread$0(CompilerExecutor.java:100)
        at java.base@17.0.7/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at java.base@17.0.7/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
        at java.base@17.0.7/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
        at java.base@17.0.7/java.lang.Thread.run(Thread.java:833)
        at org.graalvm.nativeimage.builder/com.oracle.svm.core.thread.PlatformThreads.threadStartRoutine(PlatformThreads.java:775)
        at org.graalvm.nativeimage.builder/com.oracle.svm.core.windows.WindowsPlatformThreads.osThreadStartRoutine(WindowsPlatformThreads.java:178)
Caused by: java.lang.UnsupportedOperationException
        at com.google.common.collect.ImmutableCollection.add(ImmutableCollection.java:268)
        at com.google.javascript.jscomp.OptimizeArgumentsArray.visit(OptimizeArgumentsArray.java:141)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:961)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseFunction(NodeTraversal.java:1006)
        at com.google.javascript.jscomp.NodeTraversal.handleFunction(NodeTraversal.java:857)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:903)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:1134)
        at com.google.javascript.jscomp.NodeTraversal.handleScript(NodeTraversal.java:845)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:900)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverse(NodeTraversal.java:533)
        ... 14 more

[juj]

Hmm with further testing, it looks like the issue was not "just" [].slice.call(arguments), but the fact that it was enclosed in a () => {} lambda function. I.e. happens with

console.log("enabling remote stdio logging");
const origPrint = Module['print'];
const origPrintErr = Module['printErr'];

Module['print'] = () => {
  var args = Array.prototype.slice.call(arguments);
  origPrint && origPrint(args);
  reportStdoutToServer(args.join(' '));
};

Module['printErr'] = () => {
  var args = Array.prototype.slice.call(arguments);
  origPrintErr && origPrintErr([].slice.call(args));
  reportStderrToServer(args.join(' '));
};

Changing the () => {} to function() {} avoids the internal error.

[spkapust]

Hello,

I work on the Closure team and am looking into this issue. I haven't been able to reproduce the crash with the provided snippet which suggests it might depend on specific compilation flags or the surrounding scope structure.

Could you provide the following to help us pinpoint the issue:

1. A standalone reproduction file i.e. a single .js file containing code that triggers the crash.
2. The compiler flags used
3. The compiler version you're using

This will help us isolate whether the crash is triggered by the global scope, a specific module wrapper pattern, or a particular optimization pass configuration.

Thanks!

[juj]

Thanks for the post.

I now see that this error does not occur on the latest Closure Compiler. It only happens with the Closure Compiler version that the Emscripten project is using.

C:\emsdk\emscripten\main>C:\emsdk\emscripten\main\node_modules\.bin\google-closure-compiler.cmd aaa.js
java.lang.RuntimeException: INTERNAL COMPILER ERROR.
Please report this problem.

null
  Node(NAME arguments): aaa.js:6:40
  var args = Array.prototype.slice.call(arguments);
  Parent(CALL): aaa.js:6:13
  var args = Array.prototype.slice.call(arguments);

        at com.google.javascript.jscomp.Compiler.throwInternalError(Compiler.java:3282)
        at com.google.javascript.jscomp.NodeTraversal.throwUnexpectedException(NodeTraversal.java:516)
        at com.google.javascript.jscomp.NodeTraversal.traverse(NodeTraversal.java:536)
        at com.google.javascript.jscomp.NodeTraversal$Builder.traverse(NodeTraversal.java:472)
        at com.google.javascript.jscomp.NodeTraversal.traverse(NodeTraversal.java:542)
        at com.google.javascript.jscomp.OptimizeArgumentsArray.process(OptimizeArgumentsArray.java:98)
        at com.google.javascript.jscomp.PhaseOptimizer$NamedPass.process(PhaseOptimizer.java:240)
        at com.google.javascript.jscomp.PhaseOptimizer.process(PhaseOptimizer.java:179)
        at com.google.javascript.jscomp.Compiler.performTranspilationAndOptimizations(Compiler.java:2968)
        at com.google.javascript.jscomp.Compiler.lambda$stage2Passes$7(Compiler.java:1025)
        at com.google.javascript.jscomp.CompilerExecutor.lambda$runInCompilerThread$0(CompilerExecutor.java:100)
        at java.base@17.0.7/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at java.base@17.0.7/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
        at java.base@17.0.7/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
        at java.base@17.0.7/java.lang.Thread.run(Thread.java:833)
        at org.graalvm.nativeimage.builder/com.oracle.svm.core.thread.PlatformThreads.threadStartRoutine(PlatformThreads.java:775)
        at org.graalvm.nativeimage.builder/com.oracle.svm.core.windows.WindowsPlatformThreads.osThreadStartRoutine(WindowsPlatformThreads.java:178)
Caused by: java.lang.UnsupportedOperationException
        at com.google.common.collect.ImmutableCollection.add(ImmutableCollection.java:268)
        at com.google.javascript.jscomp.OptimizeArgumentsArray.visit(OptimizeArgumentsArray.java:141)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:961)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseFunction(NodeTraversal.java:1006)
        at com.google.javascript.jscomp.NodeTraversal.handleFunction(NodeTraversal.java:857)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:903)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:1134)
        at com.google.javascript.jscomp.NodeTraversal.handleScript(NodeTraversal.java:845)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:900)
        at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:951)
        at com.google.javascript.jscomp.NodeTraversal.traverse(NodeTraversal.java:533)
        ... 14 more

C:\emsdk\emscripten\main>C:\emsdk\emscripten\main\node_modules\.bin\google-closure-compiler.cmd --version
Closure Compiler (http://github.com/google/closure-compiler)
Version: v20240317

vs

C:\Users\clb\temp\node_modules\.bin>google-closure-compiler.cmd C:\emsdk\emscripten\main\aaa.js
console.log("enabling remote stdio logging");const origPrint=Module.print,origPrintErr=Module.printErr;Module.print=()=>{var a=Array.prototype.slice.call(arguments);origPrint&&origPrint(a);reportStdoutToServer(a.join(" "))};Module.printErr=()=>{var a=Array.prototype.slice.call(arguments);origPrintErr&&origPrintErr([].slice.call(a));reportStderrToServer(a.join(" "))};

C:\Users\clb\temp\node_modules\.bin>google-closure-compiler.cmd --version
Closure Compiler (http://github.com/google/closure-compiler)
Version: v20260106

So closing this as fixed.