From d972c5064efea8297a1cae05b603f3b7a26809c6 Mon Sep 17 00:00:00 2001
From: Nick Schonning <nschonni@gmail.com>
Date: Thu, 18 Jul 2019 00:36:14 -0400
Subject: [PATCH] fix: throw on weitht passed to CSS3 invert()

See https://github.com/sass/sass-spec/pull/1444
Closes  #2899
---
 src/fn_colors.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/fn_colors.cpp b/src/fn_colors.cpp
index 64ce38048..e59b23319 100644
--- a/src/fn_colors.cpp
+++ b/src/fn_colors.cpp
@@ -361,12 +361,16 @@ namespace Sass {
     {
       // CSS3 filter function overload: pass literal through directly
       Number* amount = Cast<Number>(env["$color"]);
+      double weight = DARG_U_PRCT("$weight");
       if (amount) {
+        // TODO: does not throw on 100% manually passed as value
+        if (weight < 100.0) {
+          error("Only one argument may be passed to the plain-CSS invert() function.", pstate, traces);
+        }
         return SASS_MEMORY_NEW(String_Quoted, pstate, "invert(" + amount->to_string(ctx.c_options) + ")");
       }
 
       Color* col = ARG("$color", Color);
-      double weight = DARG_U_PRCT("$weight");
       Color_RGBA_Obj inv = col->copyAsRGBA();
       inv->r(clip(255.0 - inv->r(), 0.0, 255.0));
       inv->g(clip(255.0 - inv->g(), 0.0, 255.0));