Empty declarations sometimes being output

[xzyfer]

.foo {
  foo: unquote(null); }

Ruby Sass 3.4.12

// no output

Ruby Sass 3.4.12

DEPRECATION WARNING: Passing null, a non-string value, to unquote()
will be an error in future versions of Sass.
        on line 2 of test.scss

Libsass 3.1.0

.foo { }

Libsass 3.2.0-beta.5

.foo {
  foo: ;}

Spec added sass/sass-spec#329

[xzyfer]

Still seeing this in 3.0.0-beta.6. I'll work on a reduced test case today.

[xzyfer]

$foo: red;
$bar: unquote(null);

.baz {
    foo: $foo;
    foo: $bar; }

.bax {
    foo: $bar; }

.bay {
    foo: $foo; }

Ruby Sass

.baz {
  foo: red; }

.bay {
  foo: red; }

Libsass 3.1.0

.baz {
  foo: red; }

.bax { }

.bay {
  foo: red; }

Libsass 3.2.0-beta.6

.baz {
  foo: red;
  foo: ;}

.bay {
  foo: red; }

[xzyfer]

This appears to be due a difference in unquote

foo { 
  bar: type-of(unquote(''));
  baz: type-of(unquote(null)) }

Ruby Sass

foo {
  bar: string;
  baz: null; }

Libsass

foo {
  bar: string;
  baz: string; }

[xzyfer]

Although the current patch solves the issue of not showing empty rulesets, due to #1124 in the special case of unquote(null) this breaks if there another non-null declaration in the ruleset.

$foo: null;
foo {
  a: $foo;
  b: $foo; }
bar {
  a: b;
  b: unquote($foo); }

Ruby Sass

bar {
  a: b; }

Libsass 3.1

bar {
  a: b; }

Libsass 3.2.0-beta.6

bar {
  a: b;
  b: ;}

I have update the spec to reflect this new information - sass/sass-spec#336