modules use their own scope for module imports

this is a potentially breaking bugfix

src/parse/module.rs

@@ -7,6 +7,7 @@ use crate::{
     builtin::modules::{
         declare_module_color, declare_module_list, declare_module_map, declare_module_math,
         declare_module_meta, declare_module_selector, declare_module_string, Module, ModuleConfig,
+        Modules,
     },
     common::Identifier,
     error::SassResult,
@@ -138,7 +139,7 @@ impl<'a, 'b> Parser<'a, 'b> {
                         extender: self.extender,
                         content_scopes: self.content_scopes,
                         options: self.options,
-                        modules: self.modules,
+                        modules: &mut Modules::default(),
                         module_config: config,
                     }
                     .parse()?;

tests/use.rs

@@ -313,6 +313,45 @@ fn use_variable_redeclaration_private() {
     );
 }
 
+#[test]
+fn use_cannot_see_modules_imported_by_other_modules() {
+    let input = r#"
+       @use "use_cannot_see_modules_imported_by_other_modules__a" as a;
+       @use "use_cannot_see_modules_imported_by_other_modules__b" as b;"#;
+
+    tempfile!(
+        "use_cannot_see_modules_imported_by_other_modules__a.scss",
+        "$a: green;"
+    );
+    tempfile!(
+        "use_cannot_see_modules_imported_by_other_modules__b.scss",
+        "a { color: a.$a; }"
+    );
+
+    assert_err!("Error: There is no module with the namespace \"a\".", input);
+}
+
+#[test]
+fn use_modules_imported_by_other_modules_does_not_cause_conflict() {
+    let input = r#"
+       @use "use_modules_imported_by_other_modules_does_not_cause_conflict__a" as a;
+       @use "use_modules_imported_by_other_modules_does_not_cause_conflict__b" as b;"#;
+
+    tempfile!(
+        "use_modules_imported_by_other_modules_does_not_cause_conflict__a.scss",
+        "$a: red;"
+    );
+    tempfile!(
+        "use_modules_imported_by_other_modules_does_not_cause_conflict__b.scss",
+        "@use \"use_modules_imported_by_other_modules_does_not_cause_conflict__a\" as a; a { color: a.$a; }"
+    );
+
+    assert_eq!(
+        "a {\n  color: red;\n}\n",
+        &grass::from_string(input.to_string(), &grass::Options::default()).expect(input)
+    );
+}
+
 #[test]
 fn use_variable_redeclaration_builtin() {
     let input = "@use \"sass:math\";\nmath.$e: red;";