Problem with repeated selectors in output.

[kfalkiewicz]

Hi
Few days ago I found this interesting issue in sass - pre, and in stable version.
When I tried to change margin on few elements already styled I found that Sass compiles this rule:

article > header + .element,
article > header + .element + .element,
article > header + .element2,
article > header + .element2 + .element2 {
  margin-top: 10px;
}

to this:

article > header + .element,
article > header + .element + .element,
article > header + .element2,
article > header + .element,
article > header + .element2 + .element2,
article > header + .element + .element2,
article > header + .element2 + .element,
article > header + .element + .element {
  margin-top: 10px;
}

As you see, some selectors are repeated and some shouldn't even be created. Tried and repeated this thing on codepen.io also:
http://codepen.io/anon/pen/LFHcI

[lolmaus]

That's how extends work in Sass. See http://blackfalcon.roughdraft.io/4693231 for explanations.

My rule of thumb: never extend real selectors, only extend silent selectors.

[kfalkiewicz]

Ok thx, but why something like this happens when I do only this ?:
SCSS:

article > header + .element2,
article > header + .element2 + .element2 {
  margin-top: 10px;
}

CSS:

article > header + .element2,
article > header + .element,
article > header + .element2 + .element2,
article > header + .element + .element2,
article > header + .element2 + .element,
article > header + .element + .element {
  margin-top: 10px;
}

[lolmaus]

It does not.

[kfalkiewicz]

I mean, that when I extend .element2 class by .element class and write this selector it still create additional variations.

[lolmaus]

I gave you a link to an article that explains why it works this way.

[kfalkiewicz]

Ok so this isn't an error and I am only stupid :)