Defer throwing asset errors until after dependencies are handled. #2475

MattCheely · 2018-12-28T03:37:13Z

↪️ Pull Request

Previously submitted in #2468 and #2344 (sorry about the confusion)

This allows compiled langauges like Elm that handle their own dependency
compilation to set up watchers for dependencies so that hot-reload
continues to work due to errors in new depdenencies. Fixes #2147.

There are also a few tweaks to ElmAsset to make sure compilation errors
are thrown after dependency collection

💻 Examples

Main.elm:

module Main exposing (main)

import Html exposing (text)


main =
    text "Hello World"

Broken.elm:

module Broken exposing (anError)

{- This module causes a compiler error -}


anError : String
anError =
    2

🚨 Test instructions

Using the files above, start the parcel server, and navigate to localhost:1234.

Add a line in Main.elm to import Broken.elm:

import Broken

Notice that the build fails

Update Broken.elm by changing the value 2 to "foo".

In current parcel: no rebuild is triggered
In this branch: the error is resolved

✔️ PR Todo

I will try to create a test for this in the hmr integration tests, now that I am more familiar with the tests.

Added/updated unit tests for this change
Filled out test instructions (In case there aren't any unit tests)
Included links to related issues/PRs

This allows compiled langauges like Elm that handle their own dependency compilation to set up watchers for dependencies so that hot-reload continues to work due to errors in new depdenencies. Fixes parcel-bundler#2147.

I'm not entirely sure why this fix is necessary, but without it a compile error during a rebuild results in Parcel printing "Unknown error" instead of anything useful. Since we are intecepting the error though, we can also remove redundant stack information.

MattCheely · 2018-12-28T05:49:33Z

packages/core/parcel-bundler/src/assets/ElmAsset.js

+  generateErrorMessage(err) {
+    // For some reason, if not converted to a plain object,
+    // the error message is lost somewhere between Pipeline.js
+    // and Bundler.js.


This fixes an issue for Elm, but I probably also need to do something like this in Pipeline.js for other asset types that throw Errors. I'm not certain why this is necessary, but I suspect that there's an object copy somewhere in WorkerFarm that causes data to be lost if Pipeline.process returns an obejct containing an Error

This is fixed.

This prevents error data from being lost when Pipeline is run via `WorkerFarm`.

domenkozar · 2018-12-28T09:17:37Z

@MattCheely tests still seem to fail (although they were fixed yesterday).

MattCheely · 2018-12-28T14:35:27Z

@domenkozar Tests have been working for me locally for the most part, but I have noticed occasional timeouts on the hmr tests (mine and others), which seems to be part of the problem here. I don't have much insight into what's causing it, but there are a couple of things I can do to try simplifying the tests.

domenkozar · 2018-12-28T14:39:27Z

@DeMoorJasper is that a known issue?

DeMoorJasper · 2018-12-28T15:52:16Z

@domenkozar it only appears to be a consistent issue with this PR. But it’s a known issue that the tests are no longer stable.

_{Sent with GitHawk}

MattCheely · 2018-12-28T16:03:38Z

@DeMoorJasper I tidied up my hmr tests a bit and the last set of failures in the test run don't seem to be related to my changes. Let me know if there's something I should do to resolve that.

FWIW, one thing I have noticed is that I see hmr tests timeout more frequently when running them in isolation via: yarn run mocha --grep hmr. Usually it's the electron test that times out. When I run the full test suite, I don't think I've seen it fail, so there may be some cross-test interaction or subtle timing issues at play.

DeMoorJasper · 2018-12-28T17:58:52Z

@MattCheely Looks like you fixed it if I look at the CI results, not sure why the babel autoinstall is failing but that's probably another issue unrelated to this PR

domenkozar · 2018-12-31T12:28:30Z

I'd love to test this in my project, but couldn't find a way or documentation how to install parcel from a local folder.

MattCheely · 2018-12-31T12:50:47Z

@domenkozar to test in your project locally, run yarn build at the top of the parcel repo, then in packages/core/parcel-bundler run yarn link, which will make that folder available for linking in other projects. Then in the project you want to test with, run yarn link parcel-bundler, which will create a symlink from node_modules/parcel-bundler in that project to your local checkout.

Edit: Or are you running globally installed parcel from the command line, rather than as a local project dependency?

domenkozar · 2018-12-31T13:03:13Z

Thanks @MattCheely - it does fix the issue. I wonder if error messages are fixed though, I still see two of them:

Server running at http://localhost:12345 
🚨  /home/ielectric/dev/monorepo/frontend/src/Main.elm: Compilation failed
[================                                  ] - 1 / 3-- PARSE ERROR ----------------------------------------------------- src/Foo.elm

Something went wrong while parsing bar's definition.

4| bar = 
5| 
   ^
I was expecting to see the rest of bar's definition. Maybe you forgot some code?
Or maybe the body of `bar` needs to be indented?
Detected errors in 1 module.                                         

[================                                  ] - 1 / 3-- PARSE ERROR ----------------------------------------------------- src/Foo.elm

Something went wrong while parsing bar's definition.

4| bar =
5|
   ^
I was expecting to see the rest of bar's definition. Maybe you forgot some code?
Or maybe the body of `bar` needs to be indented?
Detected errors in 1 module.

    at ChildProcess.<anonymous> (/home/ielectric/dev/monorepo/frontend/node_modules/node-elm-compiler/index.js:149:27)
    at emitTwo (events.js:126:13)
    at ChildProcess.emit (events.js:214:7)
    at maybeClose (internal/child_process.js:925:16)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:209:5)

domenkozar · 2018-12-31T13:21:20Z

My thinking is that due to https://github.com/rtfeldman/node-elm-compiler/blob/master/src/index.ts#L126 we can't get elm not to report the error, so we could only tell parcel to skip it.

domenkozar · 2018-12-31T13:33:21Z

@MattCheely I think there was a typo, now it works correctly with:

diff --git a/packages/core/parcel-bundler/src/assets/ElmAsset.js b/packages/core/parcel-bundler/src/assets/ElmAsset.js
index 5a0f4cc..5f81ebc 100644
--- a/packages/core/parcel-bundler/src/assets/ElmAsset.js
+++ b/packages/core/parcel-bundler/src/assets/ElmAsset.js
@@ -135,7 +135,7 @@ class ElmAsset extends Asset {
   generateErrorMessage(err) {
     // The generated stack is not useful, but other code may
     // expect it and try to print it, so make it an empty string.
-    err.stack == '';
+    err.stack = '';
     return err;
   }
 }

domenkozar · 2018-12-31T13:43:11Z

Happy new year 🎉 thanks for all of the work with above patch it works great!

MattCheely · 2018-12-31T17:33:17Z

@domenkozar I will see if I can get that working again. It should be possible, at least for the parcel browser overlay. I probably accidentally reverted my previous fix when I was changing the way errors are handled in Pipeline. If I can get it fixed, I'll add a test for it so It doesn't accidentally regress again.

domenkozar · 2019-01-01T18:49:09Z

Do tests run in parallel? There are some elm corruption errors that are known issue if you mess around with cache or run things in parallel. elm/compiler#1845

Maybe doing rm -rf elm-stuff before each test could help (or separate working directories).

domenkozar · 2019-01-01T18:51:52Z

Ah actually that's probably an old annotation. https://dev.azure.com/devongovett/devongovett/_build/results?buildId=627 shows only the known transient error.

@DeMoorJasper can we merge this?

DeMoorJasper · 2019-01-02T20:57:42Z

@domenkozar unfortunately only Devon can merge PRs with failing tests.
Not sure if Azure DevOps can be configured to not block merging if tests fail as long as they're not stable

domenkozar · 2019-01-02T21:35:19Z

seems to pass now :)

domenkozar · 2019-01-03T13:29:58Z

Thank you! Now we wait for the Parcel 1.11.1 that will make Elm development with Parcel a breeze :)

domenkozar · 2019-01-09T14:14:50Z

@DeMoorJasper do you have an idea if Parcel bugfix release will happen anytime soon? So I either look into setting up using Parcel master or just wait for bugfix release. Thanks!

domenkozar · 2019-01-10T19:12:26Z

I uploaded parcel-bundler-fork to npm based on the current master to unblock my workflow. I plan to delete it as soon as 1.11.1 is out - thank you all again!

) * Defer throwing asset errors until after dependencies are handled. This allows compiled langauges like Elm that handle their own dependency compilation to set up watchers for dependencies so that hot-reload continues to work due to errors in new depdenencies. Fixes #2147. * Fix Elm error generation. I'm not entirely sure why this fix is necessary, but without it a compile error during a rebuild results in Parcel printing "Unknown error" instead of anything useful. Since we are intecepting the error though, we can also remove redundant stack information. * Add test for tracking dependencies on error * revert hmr-runtime changes * Transform all errors in Pipeline.process. This prevents error data from being lost when Pipeline is run via `WorkerFarm`. * Separate error-depenency test input from basic Elm tests. * Update ElmAsset.js

MattCheely added 2 commits December 27, 2018 22:04

Defer throwing asset errors until after dependencies are handled.

c36d1a7

This allows compiled langauges like Elm that handle their own dependency compilation to set up watchers for dependencies so that hot-reload continues to work due to errors in new depdenencies. Fixes parcel-bundler#2147.

Fix Elm error generation.

e7ba284

I'm not entirely sure why this fix is necessary, but without it a compile error during a rebuild results in Parcel printing "Unknown error" instead of anything useful. Since we are intecepting the error though, we can also remove redundant stack information.

MattCheely mentioned this pull request Dec 28, 2018

Defer throwing asset errors until after dependencies are handled. #2468

Closed

MattCheely added 2 commits December 28, 2018 00:02

Add test for tracking dependencies on error

1315f35

revert hmr-runtime changes

83335d1

MattCheely commented Dec 28, 2018

View reviewed changes

Transform all errors in Pipeline.process.

077f20e

This prevents error data from being lost when Pipeline is run via `WorkerFarm`.

Separate error-depenency test input from basic Elm tests.

a6b9358

DeMoorJasper added 2 commits December 31, 2018 16:17

Update ElmAsset.js

e1f027f

Merge branch 'master' into improve-dep-error-handling

0a2943a

Merge branch 'master' into improve-dep-error-handling

c808a4d

DeMoorJasper approved these changes Jan 3, 2019

View reviewed changes

DeMoorJasper merged commit c3d99de into parcel-bundler:master Jan 3, 2019

sklirg mentioned this pull request Jan 22, 2019

Elm: typechecking newly added imported file doesn't trigger reload #2147

Closed

domenkozar mentioned this pull request Sep 17, 2021

Elm + parcel serve unusable: File changes not detected after compilation error #6124

Closed

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Defer throwing asset errors until after dependencies are handled. #2475

Defer throwing asset errors until after dependencies are handled. #2475

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Defer throwing asset errors until after dependencies are handled. #2475

Defer throwing asset errors until after dependencies are handled. #2475

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MattCheely commented Dec 28, 2018 • edited Loading

↪️ Pull Request

💻 Examples

🚨 Test instructions

✔️ PR Todo

MattCheely Dec 28, 2018

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