<===> complex/input.scss
a b {
  a: b;
}
c {
  @extend a b;
}

<===> complex/error
Error: complex selectors may not be extended.
  ,
5 |   @extend a b;
  |           ^^^
  '
  input.scss 5:11  root stylesheet

<===> complex/error-libsass
Error: complex selectors may not be extended.
        on line 5:11 of input.scss
>>   @extend a b;

   ----------^

<===>
================================================================================
<===> compound/input.scss
a:hover {
  a: b;
}
b {
  @extend a:hover;
}

<===> compound/output-libsass.css
a:hover, b {
  a: b;
}

<===> compound/warning-libsass
WARNING on line 5, column 11 of /sass/spec/directives/extend/error/compound/input.scss:
Compound selectors may no longer be extended.
Consider `@extend a, :hover` instead.
See http://bit.ly/ExtendCompound for details.


<===> compound/error
Error: compound selectors may no longer be extended.
Consider `@extend a, :hover` instead.
See http://bit.ly/ExtendCompound for details.

  ,
5 |   @extend a:hover;
  |           ^^^^^^^
  '
  input.scss 5:11  root stylesheet