Fix a variable-assignment bug (#1372)

Closes #1250

CHANGELOG.md

@@ -1,3 +1,11 @@
+## 1.35.2
+
+* **Potentially breaking bug fix:** Fixed a bug where certain local variable
+  declarations nested within multiple `@if` statements would incorrectly
+  override a global variable. It's unlikely that any real stylesheets were
+  relying on this bug, but if so they can simply add `!global` to the variable
+  declaration to preserve the old behavior.
+
 ## 1.35.1
 
 * Fix a bug where the quiet dependency flag didn't silence warnings in some

lib/src/async_environment.dart

@@ -740,8 +740,7 @@ class AsyncEnvironment {
   /// executes [callback] and returns its result.
   Future<T> scope<T>(Future<T> callback(),
       {bool semiGlobal = false, bool when = true}) async {
-    if (!when) {
+    // We have to track semi-globalness even if `!when` so that
-      // We still have to track semi-globalness so that
     //
     //     div {
     //       @if ... {
@@ -750,8 +749,11 @@ class AsyncEnvironment {
     //     }
     //
     // doesn't assign to the global scope.
+    semiGlobal = semiGlobal && _inSemiGlobalScope;
     var wasInSemiGlobalScope = _inSemiGlobalScope;
     _inSemiGlobalScope = semiGlobal;
+
+    if (!when) {
       try {
         return await callback();
       } finally {
@@ -759,10 +761,6 @@ class AsyncEnvironment {
       }
     }
 
-    semiGlobal = semiGlobal && _inSemiGlobalScope;
-    var wasInSemiGlobalScope = _inSemiGlobalScope;
-    _inSemiGlobalScope = semiGlobal;
-
     _variables.add({});
     _variableNodes.add({});
     _functions.add({});

lib/src/environment.dart

@@ -5,7 +5,7 @@
 // DO NOT EDIT. This file was generated from async_environment.dart.
 // See tool/grind/synchronize.dart for details.
 //
-// Checksum: d5a12dbc383245a91d1e2fee0e2c4aa38939a3d8
+// Checksum: 6e5ee671e0a6e5b1d6ac87beb6aeee1e4b155d74
 //
 // ignore_for_file: unused_import
 
@@ -746,8 +746,7 @@ class Environment {
   /// If [when] is false, this doesn't create a new scope and instead just
   /// executes [callback] and returns its result.
   T scope<T>(T callback(), {bool semiGlobal = false, bool when = true}) {
-    if (!when) {
+    // We have to track semi-globalness even if `!when` so that
-      // We still have to track semi-globalness so that
     //
     //     div {
     //       @if ... {
@@ -756,8 +755,11 @@ class Environment {
     //     }
     //
     // doesn't assign to the global scope.
+    semiGlobal = semiGlobal && _inSemiGlobalScope;
     var wasInSemiGlobalScope = _inSemiGlobalScope;
     _inSemiGlobalScope = semiGlobal;
+
+    if (!when) {
       try {
         return callback();
       } finally {
@@ -765,10 +767,6 @@ class Environment {
       }
     }
 
-    semiGlobal = semiGlobal && _inSemiGlobalScope;
-    var wasInSemiGlobalScope = _inSemiGlobalScope;
-    _inSemiGlobalScope = semiGlobal;
-
     _variables.add({});
     _variableNodes.add({});
     _functions.add({});

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.35.1
+version: 1.35.2-dev
 description: A Sass implementation in Dart.
 author: Sass Team
 homepage: https://github.com/sass/dart-sass