Webpack build hangs when compiling specific scss code

[alexilyaev]

I've created a test repo to demonstrate the issue:
https://github.com/alexilyaev/webpack-sass-bug

I'm not sure if the problem is with sass-loader or there's something with the UglifyJsPlugin that's hanging the build.

Would appreciate some guidance to where to repost this issue.
And perhaps how to strip it down to test node-sass without all the Webpack stuff.

[saper]

This can be sass/node-sass#1048 which is also not easy to solve. I have prepared a workaround in sass/node-sass#1112 - if you install that, all scripts will timeout after 2000 ms and the errors will be shown.

[alexilyaev]

Well, if that will be merged, I guess it's ok.
How do I install specifically that?

[saper]

Well, if that will be merged, I guess it's ok.
How do I install specifically that?

Checkout node-sass from git

m> git clone https://github.com/sass/node-sass
Cloning into 'node-sass'...
remote: Counting objects: 8241, done.
remote: Total 8241 (delta 0), reused 0 (delta 0), pack-reused 8241
Receiving objects: 100% (8241/8241), 14.48 MiB | 3.00 MiB/s, done.
Resolving deltas: 100% (4129/4129), done.
Checking connectivity... done.
m> cd node-sass
m> git fetch origin pull/1112/head
remote: Counting objects: 33, done.
remote: Compressing objects: 100% (29/29), done.
remote: Total 33 (delta 14), reused 0 (delta 0), pack-reused 4
Unpacking objects: 100% (33/33), done.
From https://github.com/sass/node-sass

• branch refs/pull/1112/head -> FETCH_HEAD
  m> git merge FETCH_HEAD
  Updating 9a46415..dbedf5f
  Fast-forward
  binding.gyp | 1 +
  src/binding.cpp | 24 +++++++++++++++++--
  src/callback_bridge.h | 108 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------------
  src/custom_function_bridge.cpp | 3 +++
  src/custom_function_bridge.h | 1 +
  src/custom_importer_bridge.h | 1 +
  src/debug.cpp | 29 ++++++++++++++++++++++
  src/debug.h | 37 ++++++++++++++++++++++++++++
  src/sass_types/sass_value_wrapper.h | 63 +++++++++++++++++++++++++++++++++++++++++++++++-
  9 files changed, 240 insertions(+), 27 deletions(-)
  create mode 100644 src/debug.cpp
  create mode 100644 src/debug.h

then

npm install

and you need to compile the code yourself:

node script/build.js -f

The last step requires that you have python 2.x and a recent C++11 compiler installed.

[alexilyaev]

Ahm... I think I'll pass :-).

For now, I fixed my issue due to the wrong syntax in my scss code, but it will sure bite someone else.
Perhaps you can test it with my test-case repo above, and see if it actually throws the proper error after 2 seconds.

[saper]

Nope, this patch does not fix it. So it's still probably something else. With my patch applied even the original problem is relieved by the time out. Maybe it's not node-sass issue at all.

[saper]

Looking at the backtrace, this is definitely not a node-sass issue. Probably some callbacks got deadlocked in webpack.

[alexilyaev]

Should I repost somewhere?

[saper]

I don't know, this bug is probably the right place to discuss this further.

[dmitry]

I guess it's related to this file: https://github.com/webpack/webpack/blob/7c5da6580733301295b30beca1aa0eb41b6881bf/lib/optimize/UglifyJsPlugin.js

[dmitry]

Looks like the sourceMap option might be an issue.

[dmitry]

Without this block of code it runs:

        compilation.plugin("normal-module-loader", function(context) {
            context.minimize = true;
        });

[dmitry]

Looks like css-loader requests https://github.com/ben-eb/cssnano, and then it hangs.

[dmitry]

The core issue is in the https://github.com/ben-eb/postcss-minify-selectors. If I comment this processor everything works again.

[dmitry]

Finally, it's related to: https://github.com/postcss/postcss-selector-parser, please use https://github.com/postcss/postcss-selector-parser/tree/master/src/__tests__ for prooving your bug.