Print non-integer number at full precision in inspect mode

[ntkme]

• Closes Fuzzy equality requires precision of 11 while dart-sass only has precision of 10 sass#3953

sass/sass-spec#2067

[ntkme]

I did a GitHub search to find out where people are using or abusing meta.inspect. It turns out most of them are just abuses where it can be replaced with interpolation, list append, etc. In those cases this shouldn't really affect the behavior of the output.

It seems that the "legit" real world usage where this proposed change may have a small impact is: https://github.com/oddbird/true/blob/cfcd111acf0c168fd2f02cfa0c2a939dd199c189/sass/data/_details.scss#L127

@mirisuzanne @jgerigmeyer I think this change would actually make the "unpredictable" slightly better, but it would require change to the logic linked above. If you need to support both sass before and after this change, it can be implemented with a feature detection with meta.inspect(1.00000000001) == meta.inspect(1) to see if it supports high precision output for numbers in inspect mode or not.

@nex3 Any thoughts?

[nex3]

I'd like to hear what Miriam and Jonny have to say, but in principle I'm supportive of this. meta.inspect() output is generally expected to be more flexible across versions than other API surfaces; we've even got a warning to that effect in the documentation.

[jgerigmeyer]

Yeah, this logic makes sense to me. @mirisuzanne What do you think?

[mirisuzanne]

We're not using this for core functionality, and the specific level of precision is incidental to our purpose. But at some point it was common for people to be surprised when e.g. math.div(1,3) was not equal to a copy/pasted output of that equation, something like 0.3333333333. This code was just meant to warn that the Sass output of two values is equal, even though Sass doesn't consider the two values equal internally. So if you're expecting equality here, you might need to round the values.

But maybe string interpolation or some other method is better for comparing what Sass will actually output?

[nex3]

Yeah, string interpolation or "" + $value will both return the Sass serialization, where meta.inspect() will generally skew towards providing more information than can necessarily be represented by CSS (for example, it will also include complex units).