Fix explicit self variables not marking as unused -- Closes #215 (#264)

CHANGELOG.md

@@ -12,6 +12,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ### Fixed
 - Fixed internal selene panics exiting with a zero code. Panics will now exit with status code 1, allowing it to be picked up by CI.
+- Fixed variables named `self` not showing as unused if `allow_unused_self` was enabled. The implicit `self` variable being unused will still respect this configuration. [(#215)](https://github.com/Kampfkarren/selene/issues/215)
 
 ## [0.12.1] - 2021-05-26
 ### Fixed

selene-lib/src/ast_util/scopes.rs

@@ -79,6 +79,7 @@ pub struct Variable {
     pub name: String,
     pub references: Vec<Id<Reference>>,
     pub shadowed: Option<Id<Variable>>,
+    pub is_self: bool,
 }
 
 #[derive(Default)]
@@ -312,18 +313,19 @@ impl ScopeVisitor {
         self.define_name_full(&token.token().to_string(), range(token), definition_range);
     }
 
-    fn define_name_full(
+    fn define_name_full_with_variable(
         &mut self,
         name: &str,
         range: Range,
         definition_range: Range,
+        variable: Variable,
     ) -> Id<Variable> {
         let shadowed = self.find_variable(name).map(|(var, _)| var);
 
         let id = self.scope_manager.variables.alloc(Variable {
             name: name.to_owned(),
             shadowed,
-            ..Variable::default()
+            ..variable
         });
 
         self.current_scope().variables.push(id);
@@ -336,6 +338,15 @@ impl ScopeVisitor {
         id
     }
 
+    fn define_name_full(
+        &mut self,
+        name: &str,
+        range: Range,
+        definition_range: Range,
+    ) -> Id<Variable> {
+        self.define_name_full_with_variable(name, range, definition_range, Variable::default())
+    }
+
     fn try_hoist(&mut self) {
         let latest_reference_id = *self.current_scope().references.last().unwrap();
         let (name, identifier, write_expr) = {
@@ -570,7 +581,15 @@ impl Visitor<'_> for ScopeVisitor {
 
         if let Some(name) = name.method_name() {
             self.open_scope(declaration.body());
-            self.define_name_full("self", range(name), range(name));
+            self.define_name_full_with_variable(
+                "self",
+                range(name),
+                range(name),
+                Variable {
+                    is_self: true,
+                    ..Variable::default()
+                },
+            );
         }
     }
 

selene-lib/src/rules/unused_variable.rs

@@ -55,7 +55,7 @@ impl Rule for UnusedVariableLint {
             if !references.clone().any(|reference| reference.read) {
                 let mut notes = Vec::new();
 
-                if variable.name == "self" {
+                if variable.is_self {
                     if self.allow_unused_self {
                         continue;
                     }
@@ -122,6 +122,15 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_explicit_self() {
+        test_lint(
+            UnusedVariableLint::new(UnusedVariableConfig::default()).unwrap(),
+            "unused_variable",
+            "explicit_self",
+        );
+    }
+
     #[test]
     fn test_generic_for_shadowing() {
         test_lint(
@@ -149,6 +158,15 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_invalid_regex() {
+        assert!(UnusedVariableLint::new(UnusedVariableConfig {
+            ignore_pattern: "(".to_owned(),
+            ..UnusedVariableConfig::default()
+        })
+        .is_err());
+    }
+
     #[test]
     fn test_mutating_functions() {
         test_lint(
@@ -215,13 +233,4 @@ mod tests {
             "varargs",
         );
     }
-
-    #[test]
-    fn test_invalid_regex() {
-        assert!(UnusedVariableLint::new(UnusedVariableConfig {
-            ignore_pattern: "(".to_owned(),
-            ..UnusedVariableConfig::default()
-        })
-        .is_err());
-    }
 }

selene-lib/tests/lints/unused_variable/explicit_self.lua

@@ -0,0 +1,4 @@
+local function foo(self)
+end
+
+foo()

selene-lib/tests/lints/unused_variable/explicit_self.stderr

@@ -0,0 +1,6 @@
+error[unused_variable]: self is defined, but never used
+  ┌─ explicit_self.lua:1:20
+  │
+1 │ local function foo(self)
+  │                    ^^^^
+