fix: prevent merging of :host(tag) and tag

[anikethsaha]

fixes #730
closes #731

[codecov-io]

Codecov Report

Merging #876 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #876      +/-   ##
==========================================
+ Coverage   97.33%   97.33%   +<.01%     
==========================================
  Files         118      118              
  Lines        3452     3455       +3     
  Branches     1035     1036       +1     
==========================================
+ Hits         3360     3363       +3     
  Misses         84       84              
  Partials        8        8

Impacted Files	Coverage Δ
packages/postcss-merge-rules/src/index.js	97.74% <100%> (+0.03%)	⬆️

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[anikethsaha]

increasing jest timeout to 30s to fix this and for future changes as well

[codecov-commenter]

Codecov Report

Merging #876 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #876   +/-   ##
=======================================
  Coverage   97.28%   97.28%           
=======================================
  Files         118      118           
  Lines        3458     3461    +3     
  Branches     1040     1041    +1     
=======================================
+ Hits         3364     3367    +3     
  Misses         86       86           
  Partials        8        8           

Impacted Files	Coverage Δ
packages/postcss-merge-rules/src/index.js	97.74% <100.00%> (+0.03%)	⬆️

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[alexander-akait]

I think it is safe to merge, but not for all cases, it is unsafe for browsers which not supported :host https://caniuse.com/#search=host%20selector, so we should use browserslist here to ensure we can merge it or not

[anikethsaha]

@evilebottnawi

I think this fix is not required as we are already checking the compatibility.
I could write a test for IE 11 env in browserlist, but I think caniuse-lite doesnt have the :host feature in their feature data and also tried running querying with :host, css-host , host-selector and host selector but it will through ReferenceError: Please provide a proper feature name. Cannot find css-host.

So I don't think there is a way as of now to test it with the compatibility.

We can keep an eye on this list and when they add css-host we can write a test for this issue.

What do you think

[anikethsaha]

Okay I guess host is in level 1 CSS Selector ?

And I think the caniuse-lite query for that is css-selection

[alexander-akait]

@anikethsaha 👍

[anikethsaha]

Closing this as this is already done. Just need to add test, I will add that later once got to know the query for level 1 selectors in caniuse-lite