PostCSS could generate wrong source map error

[mburger81]

Ionic version: (check one with "x")
(For Ionic 1.x issues, please use https://github.com/ionic-team/ionic-v1)
[ ] 2.x
[x] 3.x
[ ] 4.x

I'm submitting a ... (check one with "x")
[x] bug report
[ ] feature request

Please do not submit support requests or "How to" questions here. Instead, please use one of these channels: https://forum.ionicframework.com/ or http://ionicworldwide.herokuapp.com/

Current behavior:
If we build a new app using your blank starter or any other template building the android app we are running into this error

[16:52:18]  sass started ... 
Witout `from` option PostCSS could generate wrong source map or do not find Browserslist config. Set it to CSS file path or to `undefined` to prevent this warning
[16:52:19]  sass finished in 1.13 s 

Expected behavior:
The bug message should not be

Steps to reproduce:
Create a new blank app using
ionic start postcss
build the android app doing
ionic cordova build android

and you can see log with the warn or error message

[16:57:54]  sass started ... 
Witout `from` option PostCSS could generate wrong source map or do not find Browserslist config. Set it to CSS file path or to `undefined` to prevent this warning
[16:57:55]  sass finished in 793 ms 

Ionic info: (run ionic info from a terminal/cmd prompt and paste output below):

cli packages: (/usr/lib/node_modules)

    @ionic/cli-utils  : 1.19.0
    ionic (Ionic CLI) : 3.19.0

global packages:

    cordova (Cordova CLI) : 8.0.0 

local packages:

    @ionic/app-scripts : 3.1.6
    Cordova Platforms  : android 7.0.0
    Ionic Framework    : ionic-angular 3.9.2

System:

    Android SDK Tools : 26.1.1
    Node              : v8.9.4
    npm               : 5.6.0 
    OS                : Linux 4.13

Environment Variables:
    ANDROID_HOME : /abcdef/android/sdk

Misc:
    backend : legacy

[StefanRein]

As the warning says:

Without from option PostCSS could generate wrong source map or do not find Browserslist config. Set it to CSS file path or to undefined to prevent this warning

I added the field from and did set it to undefined and created a pull request.

https://github.com/StefanRein/ionic-app-scripts/blob/29873ae96611ae209ca4b065fd9940d6b7b96bda/src/sass.ts#L285

This resolves this warning. But I don't know if this has further consequences and the Ionic Team needs to fill in there a path to the generated css file or something like that.

@danbucholtz Could you review this please? Our automated builds are failing because of this.
(The "warning" is interpreted as an error..)

Edit: PostCSS uses ultimately console.warn, but this goes on node to the stderr pipe and our TeamFS fails.

stderr is used for warning or error output. Source

[StefanRein]

Until this is fixed, one possibility is to revert back some patches before the error was introduced:

npm i -D -E postcss@6.0.14

CHANGELOG.md of PostCSS

6.0.16
Fix warning text (by Michael Keller).
6.0.15
Add warning about missed from option on process().then() call.
Add IE 10 support.

https://github.com/postcss/postcss/blame/master/lib/lazy-result.es6#L192

In the: package.json of ionic-app-scripts
this "postcss": "^6.0.13" installs also the new patch 6.0.15, which has the new warning.

[thezakman]

was this fixed?

[StefanRein]

@thezakman Not yet. The issue is open. The warning still exists.

[AlbenJohn]

find sass.js file. under /node_modules/@ionic/app-scripts/dist/sass.js.
find var postcssOptions and add from: undefined,

Finally should be like this:
var postcssOptions = {
from: undefined,
to: path_1.basename(sassConfig.outFile),
map: autoPrefixerMapOptions
};

[StefanRein]

ionic-team/ionic-app-scripts#1364 (comment)

You should not modify any files in the node_modules directory. If you update packages, reinstall them, installing them in a new project, any modifications are gone.

Please use the suggestion above for now.

[hanifmazlan]

i solve problem using this ( thanx also to @AlbenJohn)
https://stackoverflow.com/a/48315414

[polfernandez]

Any fix on this?

[johnroper100]

While it is not breaking my builds, this warning appears for me as well. This is a one line quick fix, is there already a pull request for this?

[StefanRein]

@johnroper100 Yes and it was approved (it's linked above).

Edit: The map files are working correctly.

[JosepAlacid]

This warning still apears.