Nested calc not resolved (with mixed units). about postcss-calc HOT 8 CLOSED

gulp.task('build-css', function () {
  return gulp.src([
    // npm resources
    'node_modules/minireset.css/minireset.css',
    'node_modules/open-color/open-color.css',
    'node_modules/flex-layout-attribute/css/flex-layout-attribute.css',
    'node_modules/modular-scale-css/modular-scale.css',
    // includes
    'resources/css/includes/*.css',
    // main files
    'resources/css/*.css',
    'resources/css/pages/*.css'
  ])
        // .pipe(sourcemaps.init())
        .pipe(plumber({errorHandler: notify.onError('Error: <%= error.message %>')}))
        .pipe(concat('app.css'))
        .pipe(size({
          'title': 'app.css before:',
          'pretty': true
        }))
        .pipe(postcss([
          require('postcss-import')(),
          require('postcss-will-change'),
          require('postcss-discard-comments'),
          require('cssnano')({
            // autoprefixer: false,
            discardComments: {
              removeAll: true
            }
            // zindex: false
          }),
          require('postcss-cssnext')({
            browsers: ['last 2 versions']
          }),
          require('postcss-color-function'),
          // require('postcss-calc-function').default(),
          require('postcss-calc')(),
          require('postcss-reporter')({
            plugins: [
              'postcss-color-function'
            ]
          })
        ]))
        .pipe(size({
          'title': 'app.css after:',
          'pretty': true
        }))
        .pipe(size({
          'title': 'app.css gzip:',
          'pretty': true,
          'gzip': true
        }))
        // .pipe(sourcemaps.write('/'))
        .pipe(gulp.dest('public/build/css'))
})

  --ms0   : var(--ms-base, 1em);
  --ms1   : calc(var(--ms-ratio, var(--golden)) * var(--ms0));
  --ms2   : calc(var(--ms-ratio, var(--golden)) * var(--ms1));