refactor(index): improve sourceMap warning message (options.sourceMap)

[teazean]

ℹ️ I've set options.sourceMap to false explicitly, but I still get warnings from dev console.

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• Bug (:label: Patch)
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• Breaking Change (:label: Major)

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[coveralls]

Coverage remained the same at 86.842% when pulling b2b65f9 on teazean:master into b9c1add on postcss:master.

[alexander-akait]

@teazean can you describe use case for this?

[teazean]

@evilebottnawi

When I was developing, I was confused by the warning tip。

Previous source map found, but options.sourceMap isn't set.

But I have already set sourceMap to false, I suspected some configuration is still wrong. It wasted a lot of time finding out why I got a warning.

I think warning tip should be more precise.

[alexander-akait]

@teazean this mean previous loader return source map, you should disable source map on all loaders, this message allow to track this problem (i.e. you previous loader generate source map but other loader after postcss don't get source map, you just spend build time on generate source maps but you don't use)

[teazean]

@evilebottnawi
yes, but maybe we can choose one from below which could be more precise:

1. change options.sourceMap isn't set to options.sourceMap is a falsy value
2. change if (!sourceMap to if (sourceMap === undefined

By the way, if I set options.sourceMap to false clearly, I will know what's the result, and then I think the warning tip is unnecessary.

[michael-ciniawsky]

@teazean This warning is mainly displayed if you have a previous source map (map, e.g from the sass-loader) and options.sourceMap = undefined || false || null in postcss-loader. If the following 2 configs still work

webpack.config,js

// 1
{
   test: /\.scss$/.
   use: [
      ...,
      { loader: 'postcss-loader', options: {} }, // warning
      { loader: 'sass-loader', options: { sourceMap: true } }
   ]
},
// 2
{
   test: /\.scss$/.
   use: [
      ...,
      { loader: 'postcss-loader', options: { sourceMap: false } }, // warning
      { loader: 'sass-loader', options: { sourceMap: true } } // if false/unset => no warning
   ]
}

but the main (your) issue is that currently explicitly setting sourceMap = false is a false negative that triggers the warning I will accept this PR. Otherwise I'm afraid have to declined it.

[michael-ciniawsky]

Please provide your current webpack.config.js aswell

[teazean]

@michael-ciniawsky Here is my warning tip.

And below is my webpack config for vue-loader options.

{
  "loaders": {
    "css": [
      "vue-style-loader",
      {
        "loader": "css-loader",
        "options": {
          "minimize": false,
          "sourceMap": false
        }
      },
      {
        "loader": "postcss-loader",
        "options": {
          "sourceMap": false
        }
      }
    ],
    "postcss": [
      "vue-style-loader",
      {
        "loader": "css-loader",
        "options": {
          "minimize": false,
          "sourceMap": false
        }
      },
      {
        "loader": "postcss-loader",
        "options": {
          "sourceMap": false
        }
      }
    ]
  },
  "transformToRequire": {
    "video": "src",
    "source": "src",
    "img": "src",
    "image": "xlink:href"
  }
}

The file compiled with warning is a Vue file with no style#lang configed

[teazean]

@michael-ciniawsky
I mean that the waring tip should not be displayed when postcss-loader#sourceMap is set to false explicitly.

Or we can change the tip, not using not set(I set the postcss-loader#sourceMap already, and why do I get a not set warning?).

[michael-ciniawsky]

@teazean If the vue-loader generates a source map this warning will still appear and rightfully so then, could you open an issue about this in vuejs/vue-loader aswell and verify if/why vue-loader adds a map of some kind here ?

[teazean]

@michael-ciniawsky
Can we just change the warning tip from options.sourceMap isn't set to options.sourceMap is a falsy value, since it actually cost a lot of time finding out why I get a warning options.sourceMap isn't set when I set options.sourceMap to false explicitly.

[Justineo]

undefined → isn't set
falsy value → is disabled

I think it's just a wording issue for the warning message.

[michael-ciniawsky]

I'm of course open to improve the warning message if it's misleading/confusing :)

[teazean]

@michael-ciniawsky
Updating warning is enough for my case. I'm closing this PR, and thanks for your explanation.👍

Looking forward to your warning improvement.

[teazean]

😞 Sorry for reopening this PR, and I will push the improved warning.

[coveralls]

Coverage remained the same at 86.842% when pulling a617b46 on teazean:master into b9c1add on postcss:master.