Empty file & gulp-sourcemaps never completes

[TuckerWhitehouse]

If I try to compile an empty less file and use gulp-sourcemaps, the task starts but never completes.

[stephenlacy]

Please add the following:

• gulpfile
• gulp, gulp-less, and gulp-sourcemap versions

[TuckerWhitehouse]

"gulp": "^3.8.10",
"gulp-less": "^2.0.1",
"gulp-load-plugins": "^0.8.0",
"gulp-sourcemaps": "^1.3.0"

var gulp = require('gulp');
var plugins = require('gulp-load-plugins')();

gulp.task('less', function () {
  gulp.src('public/**/*.less', { base: '.' })
    .pipe(plugins.sourcemaps.init())
    .pipe(plugins.less())
    .pipe(plugins.sourcemaps.write())
    .pipe(gulp.dest('.'));
});

Also tried without gulp-load-plugins, but it made no difference.

var gulp = require('gulp');
var less = require('gulp-less');
var sourcemaps = require('gulp-sourcemaps');

gulp.task('less', function () {
  gulp.src('public/**/*.less', { base: '.' })
    .pipe(sourcemaps.init())
    .pipe(less())
    .pipe(sourcemaps.write())
    .pipe(gulp.dest('.'));
});

[stephenlacy]

Can you add a example .less file?

[TuckerWhitehouse]

The issue presents itself when compiling an empty less file.

[TuckerWhitehouse]

I created a simple gist that I hope helps demonstrate the issue. I added an error listener and include the output from that in the gist.
https://gist.github.com/TuckerWhitehouse/9181bf9bb31b0fb40617

[HaNdTriX]

I am having the same issue.
Does any of you know a proper workaround?

[HaNdTriX]

For now I resoved the issue on empty files with gulp-clip-empty-files.

gulp.task('styles:dev', function() {
  return gulp.src(src)
    .pipe(watch(src))

    // Remove empty files from stream
    // To prevent sourcemaps less issue
    // https://github.com/plus3network/gulp-less/issues/122
    .pipe(clip())

    // Report errors but don't disconnect the stream
    .pipe(plumber())

    // Initialize sourcemaps
    .pipe(sourcemaps.init())

    // Compile less
    .pipe(less({
      plugins: [autoprefix]
    }))

    // Write out the sourcemaps
    .pipe(sourcemaps.write())

    // Finally, output the files to the build directory
    .pipe(gulp.dest(dest))

    // Notify Livereload
    .pipe(livereload());

});

But this doesn't work if the content of the file is an empty css rule:

body{

}

[yocontra]

@HaNdTriX Does the autoprefix plugin support sourcemaps? Try using gulp-autoprefixer instead. I had the same issue with gulp-stylus where some of the plugins were mangling sourcemaps

[HaNdTriX]

I am using less-plugin-autoprefix and it works fine.

The issue also exist without less plugins.

[yocontra]

@HaNdTriX I have received issues that say sourcemaps in less-plugin-autoprefix are broken/non-existant. Could you double check?

[TuckerWhitehouse]

The original issue I filed was without less-plugin-autoprefix, and the addition of less-plugin-autoprefix or gulp-autoprefix does not appear to have any impact.

[yocontra]

Can you try this in 2.0.3? I think it was an error reporting issue

[yocontra]

This got fixed in less/less.js#2439

[heikki]

Looks like it's broken different way now:

∴ gulp-less-test gulp less
[09:32:06] Using gulpfile ~/Desktop/gulp-less-test/gulpfile.js
[09:32:06] Starting 'less'...
[09:32:06] Finished 'less' after 8.65 ms

undefined:1
undefined
^
SyntaxError: Unexpected token u
    at Object.parse (native)
    at /Users/heikki/Desktop/gulp-less-test/node_modules/gulp-less/node_modules/accord/lib/adapters/less.js:48:32
    at /Users/heikki/Desktop/gulp-less-test/node_modules/gulp-less/node_modules/less/lib/less/render.js:35:17
    at /Users/heikki/Desktop/gulp-less-test/node_modules/gulp-less/node_modules/less/lib/less/parse.js:63:17
    at Object.finish [as _finish] (/Users/heikki/Desktop/gulp-less-test/node_modules/gulp-less/node_modules/less/lib/less/parser/parser.js:183:28)
    at Object.ImportVisitor._onSequencerEmpty (/Users/heikki/Desktop/gulp-less-test/node_modules/gulp-less/node_modules/less/lib/less/visitors/import-visitor.js:35:14)
    at ImportSequencer.tryRun (/Users/heikki/Desktop/gulp-less-test/node_modules/gulp-less/node_modules/less/lib/less/visitors/import-sequencer.js:50:14)
    at Object.ImportVisitor.run (/Users/heikki/Desktop/gulp-less-test/node_modules/gulp-less/node_modules/less/lib/less/visitors/import-visitor.js:29:25)
    at Object.Parser.parse (/Users/heikki/Desktop/gulp-less-test/node_modules/gulp-less/node_modules/less/lib/less/parser/parser.js:189:22)
    at Object.parse (/Users/heikki/Desktop/gulp-less-test/node_modules/gulp-less/node_modules/less/lib/less/parse.js:61:18)

{
  "dependencies": {
    "gulp": "^3.8.11",
    "gulp-less": "^3.0.0",
    "gulp-sourcemaps": "^1.3.0"
  }
}

var gulp = require('gulp');
var less = require('gulp-less');
var sourcemaps = require('gulp-sourcemaps');

gulp.task('less', function () {
  gulp.src('public/**/*.less', { base: '.' })
    .pipe(sourcemaps.init())
    .pipe(less())
    .pipe(sourcemaps.write())
    .pipe(gulp.dest('.'));
});

[yocontra]

@Jenius looks like an accord bug to me

[yocontra]

@Jenius https://github.com/jenius/accord/blob/master/lib/adapters/less.coffee#L24 is the culprit. Probably passing undefined to JSON.parse

@heikki if you add a guard for undefined around that JSON.parse call does it fix the problem?

[heikki]

@contra if (options.sourceMap && res.map) { on line above seems to make it pass.

[yocontra]

@heikki Maybe send a PR? Would get it fixed a lot quicker

[jescalan]

Thanks for the PR, fixed and shipped as accord@0.15.1