<===> input.scss
foo {
    color: call(missing, $a: b);
}

<===> error
DEPRECATION WARNING: Passing a string to call() is deprecated and will be illegal
in Sass 4.0. Use call(get-function("missing")) instead.

Error: Function missing doesn't support keyword arguments
        on line 2 of input.scss
  Use --trace for backtrace.

<===> error-libsass
DEPRECATION WARNING: Passing a string to call() is deprecated and will be illegal
in Sass 4.0. Use call(get-function("missing")) instead.

Error: Plain CSS function missing doesn't support keyword arguments
        on line 2:10 of inpit.scss, in function `call`
        from line 2:10 of input.scss
>>   color: call(missing, $a: b);
   ---------^

<===> error-dart-sass
DEPRECATION WARNING: Passing a string to call() is deprecated and will be illegal
in Dart Sass 2.0.0. Use call(get-function(missing)) instead.

  ,
2 |     color: call(missing, $a: b);
  |            ^^^^^^^^^^^^^^^^^^^^
  '
    input.scss 2:12  root stylesheet

Error: Plain CSS functions don't support keyword arguments.
  ,
2 |     color: call(missing, $a: b);
  |            ^^^^^^^^^^^^^^^^^^^^
  '
  input.scss 2:12  root stylesheet