Segfault parsing multiple operations in calc

[smoogly]

input.scss

div {
        $v: 1px;
        min-height: calc( #{$v} + #{$v} + #{$v} + #{$v} + #{$v} );
}

libsass 3.3.6
segmentation fault

ruby sass 3.4.21

div {
  min-height: calc( 1px + 1px + 1px + 1px + 1px );
}

version info:

node-sass   3.7.0   (Wrapper)   [JavaScript]
libsass     3.3.6   (Sass Compiler) [C/C++]

Notice following compiles properly:

div {
        $v: 1px;
        min-height: calc( #{$v} + #{$v} + #{$v} );
}

[xzyfer]

Simplified reproduction

$v: 1px;
$b: #{$v} + #{$v} + #{$v} + #{$v} + #{$v};

Interestingly this relies on deprecated Sass behaviour. It's possible this behaviour will be removed from Sass before it's patched in LibSass.

Spec added sass/sass-spec#893

[smoogly]

Thanks!