For any @errors encountered in mixins or functions, use the call-site
(instead of the @error rule) as the span printed in the error message.
Closes#474
See sass/sass-spec#1494
In #827 I made configuration never be null, but this turns out to be
overkill: we still need a way for _loadModule() and _execute() to
distinguish between "use the existing configuration" (for @forward)
and "use no configuration" (for an unconfigured @use or
meta.load-module()). We now use null as a sentinel value there, while
still ensuring that _configuration is non-nullable.
Closes#854
We switched to *updating* selectors a while ago so that cloned rules
would continue to see updates in their selectors, but we were still
generating and tracking rules in the Extender. This caused skew
between what rules the extender knew about and what rules actually
existed in situations where rules were copied (such as when resolving
nested media queries).
There's no principled reason the extender needs to know about style
rules at all, so now it just tracks modifiable wrappers of selectors.
These are re-used even when style rules are cloned, so they're safe
from the skew problem.
Closes#843
We had been using null to represent an empty configuration, but that
caused problems when an empty map snuck its way in as well. Now we
always use maps, with a const empty map for the common case.
See sass/sass#2744
`AtRootRule.query` and `Declaration.value` can be null, so this should be checked before passing them on to `visitInterpolation` and `visitExpression`.
This avoids using maps and sets with custom equality, which are
moderately inefficient relative to built-in maps and sets on both Node
and the Dart VM. In order to make error messages continue to use the
original identifiers where possible, this updates some of them to rely
more heavily on their associated source spans for context.
The default implementation runs a type check, which was a performance
bottleneck when compiled to JS. There's no need for this type check in
practice, since we never pass a non-String value to the contains(),
containsKey(), or remove() methods (and if we do, it will throw a
TypeError in our tests).
