Bug 210525

Summary: CSS :visited color taken on non-visited link when using CSS variables
Product: WebKit Reporter: Adam_Dierkens
Component: CSSAssignee: Nobody <webkit-unassigned>
Status: RESOLVED FIXED    
Severity: Major CC: beidson, darin, koivisto, sam, simon.fraser, twilco.o, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: Safari 13   
Hardware: Mac   
OS: macOS 10.14   
Attachments:
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Description Adam_Dierkens 2020-04-14 17:38:06 PDT 
When setting colors for anchor tags using css-vars, the visited color in a css-variable override is taken even if other anchor tags on the same page (that are not using css-vars) don't exhibit the same behavior.

https://jsfiddle.net/rf1njobm/3/

The first link on the page gets its styles from a --link-color-visited variable. An identical anchor tag (with the same href) that doesn't use a variable (only raw colors) doesn't appear to be visited.
Comment 1 Radar WebKit Bug Importer 2020-04-14 18:10:41 PDT 
<rdar://problem/61800412>
Comment 2 Tyler Wilcock 2020-09-04 11:27:32 PDT 
Created attachment 408005 [details]
Patch
Comment 3 Tyler Wilcock 2020-09-04 13:37:19 PDT 
Created attachment 408018 [details]
Patch
Comment 4 Darin Adler 2020-09-04 17:08:22 PDT 
Comment on attachment 408018 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=408018&action=review

> Source/WebCore/style/StyleBuilder.cpp:190
> +    auto originalLinkMatch = m_state.m_linkMatch;

This won’t do the right thing if the "return" below is done after changing m_state.m_linkMatch.

We have a class SetForScope designed for this kind of thing, that could make sure we get that right.
Comment 5 Tyler Wilcock 2020-09-04 18:06:30 PDT 
Created attachment 408059 [details]
Patch
Comment 6 Tyler Wilcock 2020-09-04 19:43:01 PDT 
TIL of SetForScope, thanks Darin!  I think I've fixed it -- can you take another look?
Comment 7 Darin Adler 2020-09-04 23:20:15 PDT 
Comment on attachment 408059 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=408059&action=review

> Source/WebCore/style/StyleBuilder.cpp:43
>  #include "StylePropertyShorthand.h"
>  
> +#include <wtf/SetForScope.h>

WebKit coding style does not leave a space between these making it two paragraphs. But fine to land like this for now.

> Source/WebCore/style/StyleBuilder.cpp:220
> +            SetForScope<SelectorChecker::LinkMatchMask> scopedLinkMatchMutation(m_state.m_linkMatch, index);

Oh, looks like there is a better way to write it:

    auto scopedLinkMatchMutation = SetForScope(m_state.m_linkMatch, index);

That way we don’t have to write out the type. But fine to land like this for now.
Comment 8 EWS 2020-09-04 23:43:41 PDT 
Committed r266656: <https://trac.webkit.org/changeset/266656>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 408059 [details].