IndexError: list assignment index out of range in create_asm_consts_wasm

[akolybelnikov]

I'm getting the following error while trying to run a build:

Traceback (most recent call last):
            File "/usr/local/Cellar/emscripten/1.38.44/libexec/emcc.py", line 3560, in <module>
              sys.exit(run(sys.argv))
            File "/usr/local/Cellar/emscripten/1.38.44/libexec/emcc.py", line 2131, in run
              final = shared.Building.emscripten(final, target + '.mem', js_libraries)
            File "/usr/local/Cellar/emscripten/1.38.44/libexec/tools/shared.py", line 2158, in emscripten
              emscripten.run(infile, outfile, memfile, js_libraries)
            File "/usr/local/Cellar/emscripten/1.38.44/libexec/emscripten.py", line 2606, in run
              return temp_files.run_and_clean(lambda: emscripter(
            File "/usr/local/Cellar/emscripten/1.38.44/libexec/tools/tempfiles.py", line 105, in run_and_clean
              return func()
            File "/usr/local/Cellar/emscripten/1.38.44/libexec/emscripten.py", line 2607, in <lambda>
              infile, outfile_obj, memfile, libraries, shared.COMPILER_ENGINE, temp_files, shared.DEBUG)
            File "/usr/local/Cellar/emscripten/1.38.44/libexec/emscripten.py", line 2215, in emscript_wasm_backend
              asm_consts, asm_const_funcs = create_asm_consts_wasm(forwarded_json, metadata)
            File "/usr/local/Cellar/emscripten/1.38.44/libexec/emscripten.py", line 2347, in create_asm_consts_wasm
              asm_consts[int(k)] = const
          IndexError: list assignment index out of range

Here is my version info:

emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 1.38.44
clang version 9.0.0 (tags/RELEASE_900/final)
Target: x86_64-apple-darwin19.2.0
Thread model: posix
InstalledDir: /usr/local/opt/llvm/bin
shared:WARNING: LLVM version appears incorrect (seeing "9.0", expected "10.0")
shared:INFO: (Emscripten: Running sanity checks)

Also, I have no idea why it expects to see LLVM "10.0".

[tlively]

Did you install emscripten using emsdk? It looks like maybe you didn't due to the "LLVM version appears incorrect" warning. Since the LLVM wasm backend and Emscripten are co-developed, it is not expected that Emscripten will work with arbitrary LLVM versions. I strongly recommend installing via emsdk, but if you must assemble your own emscripten installation, then check for known-compatible versions of the various tools at https://chromium.googlesource.com/emscripten-releases/.

All upstream LLVM commits after the LLVM 9.0 branch point have version 10.0. Emscripten uses a tip-of-tree build of LLVM, so it expects one of these 10.0 builds.

[akolybelnikov]

I haven't installed emsdk manually, it's being installed by cargo web. The warning about the LLVM version is ok, as long as it remains a warning, but the error above interferes with the build.

[sbc100]

From the error message it looks like you are using the homebrew version of emscripten, so it could be a configuration issue.

Can you trying installing via the emsdk and see if you get the same results? If that works then I would recommend filing a bug with the homebrew package.

[sbc100]

Ok I took a deeper look. I does indeed look like a mismatch between the version of binaryen and version of emscripten that are being used together.

The following change to binaryen changed the output in a way that would make the above exception occur:
WebAssembly/binaryen#2408

This change to binaryen landed 2 months ago after the 1.39.1 release of emscripten. By comparison your version of emscripten is 4 months old. So it looks like the homebrew package is somehow misconfigured.

[sbc100]

Can you run the failing command with EMCC_DEBUG=1 so I can confirm my suspicion?

[tlively]

@akolybelnikov I filed a bug on cargo-web about updating their Emscripten support. For now I would use emsdk to install Emscripten manually as a workaround https://emscripten.org/docs/getting_started/downloads.html.

[akolybelnikov]

@sbc100 , here is the error with EMCC_DEBUG=1:

https://gist.github.com/akolybelnikov/6ba29273b16cc885d702de75fcebd6f8

[sbc100]

Yes, it looks like you /usr/local/opt/binaryen is too recent. Do you know where that comes from?

[akolybelnikov]

Honestly, no idea. I followed the docs here: https://github.com/koute/cargo-web and cargo installed Emscripten in the background, and that's what I have in .emscripten :

# Note: If you put paths relative to the home directory, do not forget
# os.path.expanduser

# Note: On Windows, remember to escape backslashes! I.e. LLVM='c:\llvm\'
# is not valid, but LLVM='c:\\llvm\\' and LLVM='c:/llvm/'
# are.

import os

# This is used by external projects in order to find emscripten.  It is not used
# by emscripten itself.
EMSCRIPTEN_ROOT = os.path.expanduser(os.getenv('EMSCRIPTEN', '/usr/local/Cellar/emscripten/1.38.44/libexec')) # directory

LLVM_ROOT = os.path.expanduser(os.getenv('LLVM', '/usr/local/opt/llvm/bin')) # directory
BINARYEN_ROOT = os.path.expanduser(os.getenv('BINARYEN', '/usr/local/opt/binaryen')) # if not set, we will use it from ports

# Add this if you have manually built the JS optimizer executable (in
# Emscripten/tools/optimizer) and want to run it from a custom location.
# Alternatively, you can set this as the environment variable
# EMSCRIPTEN_NATIVE_OPTIMIZER.
# EMSCRIPTEN_NATIVE_OPTIMIZER='/path/to/custom/optimizer(.exe)'

# See below for notes on which JS engine(s) you need
NODE_JS = os.path.expanduser(os.getenv('NODE', '/Users/akolybelnikov/.nvm/versions/node/v12.12.0/bin/node')) # executable
SPIDERMONKEY_ENGINE = [os.path.expanduser(os.getenv('SPIDERMONKEY', 'js'))] # executable
V8_ENGINE = os.path.expanduser(os.getenv('V8', 'd8')) # executable

JAVA = 'java' # executable

# CLOSURE_COMPILER = '..' # define this to not use the bundled version

################################################################################


# Pick the JS engine to use for running the compiler. This engine must exist, or
# nothing can be compiled.
#
# This should be left on node.js, as that is the VM we test running the
# compiler in. Other VMs may or may not work.

COMPILER_ENGINE = NODE_JS


# All JS engines to use when running the automatic tests. Not all the engines in
# this list must exist (if they don't, they will be skipped in the test runner).
#
# Recommendation: If you already have node installed, use that. If you can, also
#                 build spidermonkey from source as well to get more test
#                 coverage.

JS_ENGINES = [NODE_JS] # add this if you have spidermonkey installed too, SPIDERMONKEY_ENGINE]

# Other options
#
# FROZEN_CACHE = True # never clears the cache, and disallows building to the cache

[sbc100]

I would file a bug with cargo-web then. It clear the binaryen version is wrong here. If its ok with you we can close this bug?

[akolybelnikov]

Thank you all for the support!