The if function is special: should be lazy.

[kaj]

The if function is special in that it's argument should be lazily evaluated. Bootstrap 5 (and probably other common scss code) relies on this.

I've tried running the cmd line on the new bootstrap 5 scss files but I get:

Error: $weight: Expected -20 to be within 0 and 100.
    ,
156 |   @return mix(white, $color, $weight);
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    '
    ../../Downloads/bootstrap-5.0.0/scss/_functions.scss 156:11  import
   ../../Downloads/bootstrap-5.0.0/scss/bootstrap-grid.scss 10:9  root stylesheet
    ,
166 |   @return if($weight > 0, shade-color($color, $weight), tint-color($color, -$weight));
    |                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    '
    ../../Downloads/bootstrap-5.0.0/scss/_functions.scss 166:57  import
    ../../Downloads/bootstrap-5.0.0/scss/bootstrap-grid.scss 10:9  root stylesheet
    ,
291 | $link-hover-color:                        shift-color($link-color, $link-shade-percentage) !default;
    |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    '
    ../../Downloads/bootstrap-5.0.0/scss/_variables.scss 291:43  import
    ../../Downloads/bootstrap-5.0.0/scss/bootstrap-grid.scss 11:9  root stylesheet

The JS implementation (using dart-sass) from their package.json seem to compile it without errors. Now according to their docs mix should be a value in between 0-100 so the error should be legit.
It would useful to vendor a few common Sass libraries and compile them as additional tests. It also gives an idea of which missing feature is commonly used.

Originally posted by @Keats in #3 (comment)

What happens in the bootstrap compiling error above is that both arguments to the if on line 166 is evaluated (even though only the $if-true one is needed) and evaluating the $if-else value causes an error.

[kaj]

Note: One down, n to go. The issue with the if function is resolved, but rsass still cant handle bootstrap.

[Keats]

@kaj I'm running into this again on master with bootstrap 5.0.1

(venv) ~/C/p/rsass (master|…) [2] $ ./target/debug/rsass ~/Downloads/bootstrap-5.0.1/scss/bootstrap.scss
Error: $weight: Expected -20 to be within 0 and 100.
    ,
156 |   @return mix(white, $color, $weight);
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    '
    /Users/vincentprouillet/Downloads/bootstrap-5.0.1/scss/_functions.scss 156:11  import
    /Users/vincentprouillet/Downloads/bootstrap-5.0.1/scss/bootstrap.scss 10:9  root stylesheet
    ,
166 |   @return if($weight > 0, shade-color($color, $weight), tint-color($color, -$weight));
    |                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    '
    /Users/vincentprouillet/Downloads/bootstrap-5.0.1/scss/_functions.scss 166:57  import
    /Users/vincentprouillet/Downloads/bootstrap-5.0.1/scss/bootstrap.scss 10:9  root stylesheet
    ,
291 | $link-hover-color:                        shift-color($link-color, $link-shade-percentage) !default;
    |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    '
    /Users/vincentprouillet/Downloads/bootstrap-5.0.1/scss/_variables.scss 291:43  import
    /Users/vincentprouillet/Downloads/bootstrap-5.0.1/scss/bootstrap.scss 11:9  root stylesheet

[kaj]

Strange, I seem to get a different error. Are you sure your ./target/debug/rsass is up to date? Note that a cargo build won't update it unless you have --features=commandline as an argument.

[Keats]

Sorry I forgot about the flag :(