Acorn optimizer - Cannot read property 'type' of undefined

[georeith]

My build is failing with the following error:

building:DEBUG: running cleanup on shell code: JSDCE minifyWhitespace
/usr/local/emsdk/upstream/emscripten/tools/acorn-optimizer.js:91
    if (!(node.type in cs)) {
               ^

TypeError: Cannot read property 'type' of undefined
    at c (/usr/local/emsdk/upstream/emscripten/tools/acorn-optimizer.js:91:16)
    at /usr/local/emsdk/upstream/emscripten/tools/acorn-optimizer.js:395:11
    at Array.forEach (<anonymous>)
    at ObjectExpression (/usr/local/emsdk/upstream/emscripten/tools/acorn-optimizer.js:394:25)
    at c (/usr/local/emsdk/upstream/emscripten/tools/acorn-optimizer.js:96:20)
    at Object.VariableDeclarator (/usr/local/emsdk/upstream/emscripten/tools/acorn-optimizer.js:390:24)
    at c (/usr/local/emsdk/upstream/emscripten/tools/acorn-optimizer.js:96:20)
    at recursiveWalk (/usr/local/emsdk/upstream/emscripten/tools/acorn-optimizer.js:98:5)
    at /usr/local/emsdk/upstream/emscripten/tools/acorn-optimizer.js:93:9
    at maybeChild (/usr/local/emsdk/upstream/emscripten/tools/acorn-optimizer.js:51:7)
em++: error: '/usr/local/emsdk/node/12.18.1_64bit/bin/node /usr/local/emsdk/upstream/emscripten/tools/acorn-optimizer.js /tmp/emscripten_temp/dwr.wasm.js.pp.js JSDCE minifyWhitespace --closureFriendly' failed (1)
cache:DEBUG: PID 110 released multiprocess file lock to Emscripten cache at /usr/local/emsdk/upstream/emscripten/cache/wasm

Here's the command I'm running:

/usr/local/emsdk/upstream/emscripten/em++.py -Oz --closure 1 -DSK_RELEASE -DGR_GL_CHECK_ALLOC_WITH_GET_ERROR=0 -I third_party/skia -I third_party/skia/third_party/icu -I third_party/skia/third_party/externals/icu/source/common/ -I include -DSK_DISABLE_AAA -DSK_FORCE_8_BYTE_ALIGNMENT -lGL -DSK_SUPPORT_GPU=1 -DSK_GL -DSK_DISABLE_LEGACY_SHADERCONTEXT -s USE_WEBGL2=1 -std=c++17 --bind --pre-js src/js/pre.js --pre-js src/js/interface.js src/Canvas.cpp src/Rectangle.cpp src/RenderList.cpp src/RenderObject.cpp src/RenderObjectContainer.cpp src/Shape.cpp src/Text.cpp src/main.cpp /root/design-wasm-renderer/third_party/skia/out/lib/libskparagraph.a /root/design-wasm-renderer/third_party/skia/out/lib/libskshaper.a /root/design-wasm-renderer/third_party/skia/out/lib/libharfbuzz.a /root/design-wasm-renderer/third_party/skia/out/lib/libicu.a /root/design-wasm-renderer/third_party/skia/out/lib/libskia.a /root/design-wasm-renderer/third_party/skia/modules/canvaskit/fonts/NotoMono-Regular.ttf.cpp -s EXPORT_NAME='Module' -s ALLOW_MEMORY_GROWTH=1 -s INITIAL_MEMORY=128MB -s NO_EXIT_RUNTIME=1 -s STRICT=1 -s WASM=1 -s USE_BOOST_HEADERS=1 -s LLD_REPORT_UNDEFINED -s ASSERTIONS=1 -s SAFE_HEAP=1 -Wl,-error-limit=0 -o out/dwr.js

version: 2.0.7

[kripken]

This doesn't sound like a known issue, but we'd need a testcase to debug it @georeith

Or you can debug it on your side by seeing if it's something specific in your user-provided JS (check if removing a --pre-js for example makes a difference).

[georeith]

@kripken thanks for the pointer on where to start. I narrowed it down to this function in my --pre-js:

  DWR.Text.prototype.generateFontCache = function () {
    const fontCache = {};
    const _fontCache = this._generateFontCache();
    const _fontNames = _fontCache.keys();
    for (let i = 0; i < _fontCache.size(); i++) {
      const fontName = _fontNames.get(i);
      const _fontData = _fontCache.get(fontName);
      const glyphCache = {};
      const fontData = {
        ..._fontData,
        glyphs: glyphCache,
      };
      fontCache[fontName] = fontData;
      const _glyphCache = _fontData.glyphs;
      const _glyphIds = _glyphCache.keys();
      for (let j = 0; j < _glyphCache.size(); j++) {
        const glyphId = _glyphIds.get(j);
        glyphCache[glyphId] = _glyphCache.get(glyphId);
      }
    }

    return fontCache;
  };

Specifically the spread operation here:

const fontData = {
    ..._fontData,
    glyphs: glyphCache,
};

Replacing it with this removes the issue:

const fontData = Object.assign({}, _fontData, {
  glyphs: glyphCache,
});

[kripken]

Interesting, thanks for the update @georeith

It would be good to check if this is an issue in upstream acorn (if so we should update, or if not, file an issue). We do already pass ecmaVersion: 2020 so we should be using everything acorn supports.

[sbc100]

We did only recently switch to 2020 though... what version of emscripten are you using? (if you are using a git checkout, have you run npm install recently?)

[sbc100]

We did only recently switch to 2020 though... what version of emscripten are you using? (if you are using a git checkout, have you run npm install recently?)

Ignore this I see you are using 2.0.7 and the emsdk.

[sbc100]

@kripken looks like maybe a bug in our acorn-optimizer.js code which uses acorn, rather than an issue with acorn itself?

[kripken]

@sbc100 Worth investigating, yes. But the stack trace is on

    if (!(node.type in cs)) {

which suggests the node is undefined. That seems less likely to be a bug in our code.

[stale]

This issue has been automatically marked as stale because there has been no activity in the past year. It will be closed automatically if no further activity occurs in the next 30 days. Feel free to re-open at any time if this issue is still relevant.

[Ghabry]

I just had this issue in code starting with this line: Module = { ...Module,.

Applied the mentioned Object.assign workaround to make it compile

[pavelsavara]

The node looks like this

{
            "type": "SpreadElement",
            "start": 185894,
            "end": 185899,
            "argument": {
                "type": "Identifier",
                "start": 185897,
                "end": 185899,
                "name": "Va"
            }
        }

It fails in

ObjectExpression(node, c) {
        // ignore the property identifiers
        node.properties.forEach(function (node) {
          c(node.value);
        });
      },

because the node doesn't have value

It probably should be handled by hasSideEffects().