more robustly parse commas in call args

src/parse/args.rs

@@ -160,6 +160,16 @@ impl<'a, 'b> Parser<'a, 'b> {
                 return Ok(CallArgs(args, span));
             }
 
+            if self.consume_char_if_exists(',') {
+                self.whitespace_or_comment();
+
+                if self.consume_char_if_exists(',') {
+                    return Err(("expected \")\".", self.span_before).into());
+                }
+
+                continue;
+            }
+
             if let Some(Token { kind: '$', pos }) = self.toks.peek() {
                 let start = self.toks.cursor();
 
@@ -222,6 +232,9 @@ impl<'a, 'b> Parser<'a, 'b> {
                         value,
                     );
                     self.whitespace_or_comment();
+                    if self.consume_char_if_exists(',') {
+                        return Err(("expected \")\".", self.span_before).into());
+                    }
                     continue;
                 }
                 Some(Token { kind: '.', pos }) => {

src/parse/value/eval.rs

@@ -79,13 +79,13 @@ impl<'a, 'b: 'a, 'c> ValueVisitor<'a, 'b, 'c> {
                         op,
                         Box::new(val2),
                     ));
-                } else {
-                    return Ok(HigherIntermediateValue::BinaryOp(
-                        val1_1,
-                        val1_op,
-                        Box::new(self.bin_op_one_level(*val1_2, op, val2, in_parens)?),
-                    ));
                 }
+
+                return Ok(HigherIntermediateValue::BinaryOp(
+                    val1_1,
+                    val1_op,
+                    Box::new(self.bin_op_one_level(*val1_2, op, val2, in_parens)?),
+                ));
             }
             _ => unreachable!(),
         };
@@ -132,13 +132,13 @@ impl<'a, 'b: 'a, 'c> ValueVisitor<'a, 'b, 'c> {
         if let HigherIntermediateValue::BinaryOp(val1_1, val1_op, val1_2) = val1 {
             let in_parens = op != Op::Div || val1_op != Op::Div;
 
-            if val1_op.precedence() >= op.precedence() {
+            return if val1_op.precedence() >= op.precedence() {
                 val1 = self.bin_op_one_level(*val1_1, val1_op, *val1_2, in_parens)?;
-                return self.bin_op(val1, op, val2, in_parens);
+                self.bin_op(val1, op, val2, in_parens)
             } else {
                 val2 = self.bin_op_one_level(*val1_2, op, val2, in_parens)?;
-                return self.bin_op(*val1_1, val1_op, val2, in_parens);
-            }
+                self.bin_op(*val1_1, val1_op, val2, in_parens)
+            };
         }
 
         Ok(match op {

tests/args.rs

@@ -231,3 +231,47 @@ test!(
     }",
     "a {\n  color: foo;\n  color: bar;\n  color: foo;\n}\n"
 );
+test!(
+    splat_ends_with_comma,
+    "@function foo($arg1) {
+      @return $arg1;
+    }    
+
+    a {
+        color: foo(a...,);
+    }",
+    "a {\n  color: a;\n}\n"
+);
+test!(
+    two_splat_ends_with_comma,
+    "@function foo($arg1, $arg2) {
+      @return $arg1 $arg2;
+    }    
+
+    a {
+        color: foo((value1,)..., (arg2: value2)...);
+    }",
+    "a {\n  color: value1 value2;\n}\n"
+);
+error!(
+    splat_ends_with_two_commas,
+    "@function foo($arg1) {
+      @return $arg1;
+    }    
+
+    a {
+        color: foo(a...,,);
+    }",
+    "Error: expected \")\"."
+);
+error!(
+    arg_ends_with_two_commas,
+    "@function foo($arg1) {
+      @return $arg1;
+    }    
+
+    a {
+        color: foo(a,,);
+    }",
+    "Error: expected \")\"."
+);