Combined with stylus produced wrong sourcemap

Hi! There is my config:

gulp.task('cssbuild', function () {
  gulp.src(paths.stylSrc)
    .pipe(sourcemaps.init())
    .pipe(stylus())
    .pipe(postcss([
         autoprefixer({ browsers: ['ie >= 9', 'last 2 versions'] }),
         csso()
     ]))
    .pipe(sourcemaps.write('.'))
    .pipe(gulp.dest(paths.output));
})

after that I get only partly work source map for example:

if I not use gulp-postcss or use ‘poststylus’ with autoprefixer inside (poststylus allow use postcss like stylus plugins) - everything works fine.

[w0rm]

So I investigated further, and it looks that the problem might be in the combination with postcss-csso, that is not a real postcss plugin, because it converts between different ASTs internally. Try using it as a gulp plugin gulp-csso, and include after postcss in your gulp pipeline.

Change this

var csso = require('postcss-csso');

.pipe(postcss([
         autoprefixer({browsers: ['ie >= 9', 'last 2 versions']}),
         csso()
     ]))

to this:

var csso = require('gulp-csso');

    .pipe(postcss([
         autoprefixer({browsers: ['ie >= 9', 'last 2 versions']})
     ]))
    .pipe(csso())

[ai]

cc @lahmatiy