resolve regression in @mixin scoping

CHANGELOG.md

@@ -1,6 +1,7 @@
 # 0.9.1
+
  - fix regression in which `@at-root` would panic when placed after a ruleset
- - fix regression related to `@mixin` scoping and outer, local variables
+ - fix regression related to `@mixin` and `@function` scoping when combined with outer, local variables
 
 # 0.9.0
 

src/parse/common.rs

@@ -25,6 +25,14 @@ impl<T> NeverEmptyVec<T> {
         self.rest.last_mut().unwrap_or(&mut self.first)
     }
 
+    pub fn first(&mut self) -> &T {
+        &self.first
+    }
+
+    pub fn first_mut(&mut self) -> &mut T {
+        &mut self.first
+    }
+
     pub fn push(&mut self, value: T) {
         self.rest.push(value)
     }

src/parse/function.rs

@@ -3,7 +3,6 @@ use std::mem;
 use codemap::Spanned;
 use peekmore::PeekMore;
 
-use super::{Parser, Stmt};
 use crate::{
     args::CallArgs,
     atrule::Function,
@@ -13,6 +12,8 @@ use crate::{
     Token,
 };
 
+use super::{NeverEmptyVec, Parser, Stmt};
+
 impl<'a> Parser<'a> {
     pub(super) fn parse_function(&mut self) -> SassResult<()> {
         if self.in_mixin {
@@ -62,13 +63,12 @@ impl<'a> Parser<'a> {
 
     pub fn eval_function(&mut self, mut function: Function, args: CallArgs) -> SassResult<Value> {
         self.eval_fn_args(&mut function, args)?;
-        self.scopes.push(function.scope);
 
         let mut return_value = Parser {
             toks: &mut function.body.into_iter().peekmore(),
             map: self.map,
             path: self.path,
-            scopes: self.scopes,
+            scopes: &mut NeverEmptyVec::new(function.scope),
             global_scope: self.global_scope,
             super_selectors: self.super_selectors,
             span_before: self.span_before,
@@ -81,8 +81,6 @@ impl<'a> Parser<'a> {
         }
         .parse()?;
 
-        self.scopes.pop();
-
         debug_assert!(return_value.len() <= 1);
         match return_value
             .pop()

src/parse/mixin.rs

@@ -6,13 +6,12 @@ use crate::{
     args::{CallArgs, FuncArgs},
     atrule::Mixin,
     error::SassResult,
-    scope::Scope,
     utils::read_until_closing_curly_brace,
     value::Value,
     Token,
 };
 
-use super::{Parser, Stmt};
+use super::{NeverEmptyVec, Parser, Stmt};
 
 impl<'a> Parser<'a> {
     pub(super) fn parse_mixin(&mut self) -> SassResult<()> {
@@ -41,7 +40,7 @@ impl<'a> Parser<'a> {
         // this is blocked on figuring out just how to check for this. presumably we could have a check
         // not when parsing initially, but rather when `@include`ing to see if an `@content` was found.
 
-        let mixin = Mixin::new(Scope::new(), args, body, false);
+        let mixin = Mixin::new(self.scopes.last().clone(), args, body, false);
 
         if self.at_root {
             self.global_scope.insert_mixin(name, mixin);
@@ -97,13 +96,11 @@ impl<'a> Parser<'a> {
         let mut mixin = self.scopes.last().get_mixin(name, self.global_scope)?;
         self.eval_mixin_args(&mut mixin, args)?;
 
-        self.scopes.push(mixin.scope);
-
         let body = Parser {
             toks: &mut mixin.body,
             map: self.map,
             path: self.path,
-            scopes: self.scopes,
+            scopes: &mut NeverEmptyVec::new(mixin.scope),
             global_scope: self.global_scope,
             super_selectors: self.super_selectors,
             span_before: self.span_before,
@@ -116,8 +113,6 @@ impl<'a> Parser<'a> {
         }
         .parse()?;
 
-        self.scopes.pop();
-
         Ok(body)
     }
 

src/parse/variable.rs

@@ -81,6 +81,11 @@ impl<'a> Parser<'a> {
                     scope.insert_var(ident.clone(), value.value.clone())?;
                 }
             }
+            if self.scopes.first().var_exists_no_global(&ident) {
+                self.scopes
+                    .first_mut()
+                    .insert_var(ident.clone(), value.value.clone())?;
+            }
             self.scopes.last_mut().insert_var(ident, value.value)?;
         }
         Ok(())

tests/functions.rs

@@ -99,3 +99,25 @@ error!(
     body_missing_closing_curly_brace,
     "@function foo() {", "Error: expected \"}\"."
 );
+test!(
+    does_not_modify_local_variables,
+    "@function bar($color-name) {
+        @if $color-name==bar {
+            @error bar;
+        }
+
+        $color: bar;
+        @return null;
+    }
+
+    @function foo($a, $b) {
+        @return \"success!\";
+    }
+
+    a {
+        $color: foo;
+    
+        color: foo(bar($color), bar($color));
+    }",
+    "a {\n  color: \"success!\";\n}\n"
+);