JS build issues

[dcodeIO]

The binaryen.js bot is currently failing with

In file included from binaryen/src/shell-interface.h:28:
binaryen/src/wasm-interpreter.h:1783:28: error: 'auto' not allowed in lambda parameter
      auto fillLanes = [&](auto lanes, size_t laneBytes) {

Wondering if this has something to do with the bot still using fastcomp, or if it's something else?

[MaxGraey]

It also use Clang 5.0.0

[dcodeIO]

Yeah, it uses Clang 5 to compile LLVM/Emscripten (which works), but the error is from Emscripten compiling Binaryen.

[kripken]

I suspect this is related to the recent upgrade in Binaryen to use c++14 (and temporary c++17, which we reverted), cc @tlively

[sbc100]

Looks like you are building in ubuntu/trusty image which is really old now. There are two more recent ubuntu LTS images: xenial and bionic. Is there some way you can switch to one of those?

[dcodeIO]

Yeah, plan is to update the bot to use the Emscripten docker image eventually, though I think that the issue here is not necessarily related to the OS. The build script compiles and then uses Emscripten incoming, which then emits this error when trying to compile Binaryen.

[tlively]

auto in lambda parameters is the feature from C++14 that prompted us to upgrade from C++11. It looks like the bot is still using C++11. Perhaps you need to update here: https://github.com/AssemblyScript/binaryen.js/blob/master/scripts/build.js#L46.

[dcodeIO]

Thanks, that's probably it. Decided to switch to the Emscripten docker image meanwhile, which builds fine again using build-js.sh. Speaking of which, I guess this line in build-js.sh needs to be downgraded to C++14 as well?

[tlively]

Yep! Handled in #2360.

[dcodeIO]

Perfect! :)