These were discovered by LibSass and Sass Spec. As the LibSass team closes in on parity Sass' small inconsistencies make Sass Spec angry at us. Below are some of the one currently hurting us. I'd PR a fix myself but there it's not clear which is right way to go.
Too many arguments.
This was mistake on my behalf.
Deprecations warnings
WARNING: Function bar takes 4 arguments but 5 were passed.
on line 23 of test.scss
This will be an error in future versions of Sass.
DEPRECATION WARNING on line 15 of test.scss:
Naming a function "url" is disallowed and will be an error in future versions of Sass.
This name conflicts with an existing CSS function with special parse rules.
DEPRECATION WARNING: Passing null, a non-string value, to unquote()
will be an error in future versions of Sass.
on line 15 of test.scss
Inconsistencies with file path. Sometimes the file path displayed in console messages is relative, other times it's absolute. I've been update to reverse engineer a reliable algorithm for when to use which. I suspect it's non-standard.
$ sass /sass/sass-spec/spec/libsass-closed-issues/issue_1681/url/input.scss
DEPRECATION WARNING on line 1 of /sass/sass-spec/spec/libsass-closed-issues/issue_1681/url/input.scss:
Naming a function "url" is disallowed and will be an error in future versions of Sass.
This name conflicts with an existing CSS function with special parse rules.
$ sass sass-spec/spec/libsass-closed-issues/issue_1681/url/input.scss
DEPRECATION WARNING on line 1 of sass-spec/spec/libsass-closed-issues/issue_1681/url/input.scss:
Naming a function "url" is disallowed and will be an error in future versions of Sass.
This name conflicts with an existing CSS function with special parse rules.
$ sass ../sass-spec/spec/libsass-closed-issues/issue_1681/url/input.scss
DEPRECATION WARNING on line 1 of ../sass-spec/spec/libsass-closed-issues/issue_1681/url/input.scss:
Naming a function "url" is disallowed and will be an error in future versions of Sass.
This name conflicts with an existing CSS function with special parse rules.
$ sass foo/test.scss
DEPRECATION WARNING on line 6 of foo/test.scss:
Naming a function "url" is disallowed and will be an error in future versions of Sass.
This name conflicts with an existing CSS function with special parse rules.
From https://github.com/sass/sass/issues/1880: