Compass linear-gradient causes error when used with svg

[sjdemartini]

The following fails to process properly. Looks like the Sass List isn't being created properly when the first argument is the position, maybe? (Note that this used to work; the file parses fine with pyscss version 1.1.3.)

@import "compass/css3";
div {
    @include background-image(linear-gradient(top, #1F9CCA 0%, #2072B0 100%));
}   

Traceback (most recent call last):
  File "/Users/sjd/Envs/env_newpyscss/bin/pyscss", line 9, in <module>
    load_entry_point('pyScss==1.2.0.post3', 'console_scripts', 'pyscss')()
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/tool.py", line 149, in main
    do_build(options, args)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/tool.py", line 176, in do_build
    output.write(css.compile(scss_file=path, is_sass=options.is_sass))
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 438, in compile
    return self.Compilation(*args, **kwargs)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 396, in Compilation
    self.parse_children()
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/util.py", line 111, in wrapper
    return func(*args, **kwargs)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 489, in parse_children
    self.manage_children(rule, scope)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/util.py", line 111, in wrapper
    return func(*args, **kwargs)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 498, in manage_children
    self._manage_children_impl(rule, scope)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 596, in _manage_children_impl
    self._nest_rules(rule, scope, block)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/util.py", line 111, in wrapper
    return func(*args, **kwargs)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 1310, in _nest_rules
    self.manage_children(new_rule, scope)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/util.py", line 111, in wrapper
    return func(*args, **kwargs)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 498, in manage_children
    self._manage_children_impl(rule, scope)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 561, in _manage_children_impl
    self._do_include(rule, scope, block)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/util.py", line 111, in wrapper
    return func(*args, **kwargs)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 832, in _do_include
    self.manage_children(_rule, scope)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/util.py", line 111, in wrapper
    return func(*args, **kwargs)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 498, in manage_children
    self._manage_children_impl(rule, scope)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 565, in _manage_children_impl
    self._do_if(rule, scope, block)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/util.py", line 111, in wrapper
    return func(*args, **kwargs)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 1042, in _do_if
    self.manage_children(inner_rule, scope)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/util.py", line 111, in wrapper
    return func(*args, **kwargs)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 498, in manage_children
    self._manage_children_impl(rule, scope)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 583, in _manage_children_impl
    self._get_properties(rule, scope, block)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/util.py", line 111, in wrapper
    return func(*args, **kwargs)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/__init__.py", line 1212, in _get_properties
    value = calculator.calculate(raw_value)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/expression.py", line 104, in calculate
    better_expr_str = self.evaluate_expression(better_expr_str, divide=divide)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/expression.py", line 132, in evaluate_expression
    raise SassEvaluationError(e, expression=expr)
scss.errors.SassEvaluationError: Error evaluating expression:
    -svg($images)

...

Traceback:
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/expression.py", line 130, in evaluate_expression
    return ast.evaluate(self, divide=divide)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/expression.py", line 314, in evaluate
    ret = funct(*args, **kwargs)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/functions/compass/helpers.py", line 187, in dash_svg
    return prefix('_svg', *args)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/functions/compass/helpers.py", line 168, in prefix
    _value.append(to_fnct())
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/functions/compass/gradients.py", line 328, in to__svg
    return linear_svg_gradient(color_stops, position_and_angle or 'top')
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/functions/compass/gradients.py", line 353, in linear_svg_gradient
    args = List.from_maybe_starargs(args)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/types.py", line 616, in from_maybe_starargs
    return cls(args, use_comma=use_comma)
  File "/Users/sjd/Envs/env_newpyscss/lib/python2.7/site-packages/scss/types.py", line 563, in __init__
    raise TypeError("Expected a Sass type, got %r" % (item,))
TypeError: Expected a Sass type, got [(<Number(0.0%)>, <Color((31.0, 156.0, 202.0, 1.0))>), (<Number(100.0%)>, <Color((32.0, 114.0, 176.0, 1.0))>)]

[eevee]

It doesn't crash any more, but I have no idea if it works correctly — our Compass gradient stuff is very dense and not very well defined or tested :(

[sjdemartini]

Ah okay. Well thanks for looking into it and fixing the crash!

[simpoir]

I had the same problem which I traced back to this commit 028b73079c221f97f7ff1a9537a88279b8c0b098

There seems to be a return statement that disappeared on line extension/compass/gradients.py:25

Change

 list(args[0])

to

return list(arg[0])

and it already works better

[eevee]

@simpoir whoops, fixed that, thanks! I should be making a point release today or tomorrow.

I'm gonna close this, but feel free to open new issues for further problems. Eventually I hope to make the Compass support a little more well-defined and well-tested.