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arciisine opened this issue Sep 15, 2016 · 8 comments
Closed

Unable to destructure let assignments #2012

arciisine opened this issue Sep 15, 2016 · 8 comments
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@Dominator008
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bug ES6

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@arciisine
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I'm working on compiling some generated code, and I seem to be running into an unexpected error when attempting to destructure an array using a let declaration. Changing the let to a var resolves the issue. It looks like the issue could be related to #1124.

The sample code:

(function() {
      'use strict';

      return function _gen82026814(_gen12526804, _gen51426798, _gen59126807) {
    var _gen43726760 = _gen59126807[0], _zzx8_exec = _gen59126807[1], k = _gen59126807[2], x = _gen59126807[3];
    var _gen33726797 = 0, _gen31026800 = null, _gen31926806 = _gen12526804.length;
    _gen21426802:
        for (var _gen71326803 = 0; _gen71326803 < _gen31926806; _gen71326803 += 1) {
            var _gen58026799 = _gen12526804[_gen71326803];
            let [ops_83626812, fn_98826813] = _gen58026799;
            _zzx8_exec(ops_83626812, '__key6326761', _gen43726760, [[
                    function _gen99626759(x, op, i) {
                        let j = (3 - i % 4 + 1) % 4;
                        x[j] = fn_98826813(x[j], x[(j + 1) % 4], x[(j + 2) % 4], x[(j + 3) % 4], k[op[0]], op[1], op[2]);
                        return x;
                    },
                    x
                ]], [
                fn_98826813,
                k
            ]);
            _gen33726797 += 1;
        }
    return {
        value: _gen31026800,
        assigned: []
    };
};
    })()

With running this with the closure compiler, I received the following error:

23: java.lang.RuntimeException: INTERNAL COMPILER ERROR.
Please report this problem.

Invalid attempt to remove node: VAR 9 [length: 699] [source_file: Input_0] of LABEL 8 [length: 13] [source_file: Input_0]
  Node(VAR): Input_0:9:8
        for (var _gen71326803 = 0; _gen71326803 < _gen31926806; _gen71326803 += 1) {
  Parent(LABEL): Input_0:8:4
    _gen21426802:

    at com.google.javascript.jscomp.NodeUtil.removeChild(NodeUtil.java:2680)
    at com.google.javascript.jscomp.UnreachableCodeElimination$EliminationPass.removeNode(UnreachableCodeElimination.java:262)
    at com.google.javascript.jscomp.UnreachableCodeElimination$EliminationPass.removeDeadExprStatementSafely(UnreachableCodeElimination.java:252)
    at com.google.javascript.jscomp.UnreachableCodeElimination$EliminationPass.visit(UnreachableCodeElimination.java:103)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:650)
    at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:722)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:646)
    at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:722)
    at com.google.javascript.jscomp.NodeTraversal.traverseBlockScope(NodeTraversal.java:737)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:644)
    at com.google.javascript.jscomp.NodeTraversal.traverse(NodeTraversal.java:332)
    at com.google.javascript.jscomp.NodeTraversal.traverseEs6(NodeTraversal.java:595)
    at com.google.javascript.jscomp.UnreachableCodeElimination$1.enterFunction(UnreachableCodeElimination.java:80)
    at com.google.javascript.jscomp.NodeTraversal$1.shouldTraverse(NodeTraversal.java:572)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:633)
    at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:722)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:646)
    at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:722)
    at com.google.javascript.jscomp.NodeTraversal.traverseBlockScope(NodeTraversal.java:737)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:644)
    at com.google.javascript.jscomp.NodeTraversal.traverseFunction(NodeTraversal.java:681)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:638)
    at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:722)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:646)
    at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:722)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:646)
    at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:722)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:646)
    at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:722)
    at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:646)
    at com.google.javascript.jscomp.NodeTraversal.traverse(NodeTraversal.java:332)
    at com.google.javascript.jscomp.NodeTraversal.traverseEs6(NodeTraversal.java:595)
    at com.google.javascript.jscomp.NodeTraversal.traverseChangedFunctions(NodeTraversal.java:567)
    at com.google.javascript.jscomp.UnreachableCodeElimination.process(UnreachableCodeElimination.java:65)
    at com.google.javascript.jscomp.PhaseOptimizer$NamedPass.process(PhaseOptimizer.java:285)
    at com.google.javascript.jscomp.PhaseOptimizer$Loop.process(PhaseOptimizer.java:458)
    at com.google.javascript.jscomp.PhaseOptimizer.process(PhaseOptimizer.java:217)
    at com.google.javascript.jscomp.Compiler.optimize(Compiler.java:2049)
    at com.google.javascript.jscomp.Compiler.compileInternal(Compiler.java:759)
    at com.google.javascript.jscomp.Compiler.access$000(Compiler.java:85)
    at com.google.javascript.jscomp.Compiler$2.call(Compiler.java:701)
    at com.google.javascript.jscomp.Compiler$2.call(Compiler.java:698)
    at com.google.javascript.jscomp.CompilerExecutor.runInCompilerThread(CompilerExecutor.java:118)
    at com.google.javascript.jscomp.Compiler.runInCompilerThread(Compiler.java:728)
    at com.google.javascript.jscomp.Compiler.compile(Compiler.java:698)
    at com.google.javascript.jscomp.Compiler.compile(Compiler.java:668)
    at com.google.javascript.jscomp.webservice.backend.CompilerInvokerImpl.compile(CompilerInvokerImpl.java:46)
    at com.google.javascript.jscomp.webservice.backend.ServerController.executeRequest(ServerController.java:178)
    at com.google.javascript.jscomp.webservice.backend.CompilationRequestHandler.serviceParsedRequest(CompilationRequestHandler.java:178)
    at com.google.javascript.jscomp.webservice.backend.CompilationRequestHandler.service(CompilationRequestHandler.java:160)
    at com.google.javascript.jscomp.webservice.frontend.CompilationServlet.doPost(CompilationServlet.java:83)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
    at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:125)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:37)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.JdbcMySqlConnectionCleanupFilter.doFilter(JdbcMySqlConnectionCleanupFilter.java:60)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:50)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:260)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
    at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:78)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:148)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:504)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:446)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:453)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:276)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:312)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:304)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:450)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:235)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalStateException: Invalid attempt to remove node: VAR 9 [length: 699] [source_file: Input_0] of LABEL 8 [length: 13] [source_file: Input_0]
    ... 85 more
@Dominator008
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Can you try removing the label _gen21426802: and see if that fixes the problem?

@arciisine
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Removing the label also resolved the issue. So it does appear to be the combination of the label and the let statement together.

@Dominator008 Dominator008 self-assigned this Sep 15, 2016
@brad4d
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brad4d commented Sep 15, 2016

I would guess that it works with 'var' because the UnreachableCodeElimination pass knows that 'var's are hoisted making it unsafe to remove them.

@Dominator008 do you think UnreachableCodeElimination is assuming that code after a label that is never mentioned is automatically unreachable?

@Dominator008
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Dominator008 commented Sep 15, 2016 •
edited
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@brad4d I think this might be a bug with Es6RewriteBlockScopedDeclarations.

@Dominator008
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@arciisine Did you use SIMPLE_OPTIMIZATIONS?

@arciisine
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For the above, yeah

@Dominator008
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@arciisine Cool thanks. I have a fix for this internally. It will be pushed out soon :)

@arciisine
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Awesome @Dominator008, looking forward to it.

alexeykomov pushed a commit to alexeykomov/closure-compiler that referenced this issue Feb 8, 2017
@Dominator008 @alexeykomov
Properly handle labeled loops in Es6RewriteBlockScopedDeclaration
11a528c 
Fixes google#2012 on GitHub.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=133411970
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@brad4d @arciisine @Dominator008