fix: add a check for multiple definitions of the type alias

Author: LesterEvSe

src/ast.rs

@@ -618,8 +618,35 @@ impl Scope {
     /// There are any undefined aliases.
     pub fn insert_alias(&mut self, name: AliasName, ty: AliasedType) -> Result<(), Error> {
         let resolved_ty = self.resolve(&ty)?;
-        self.aliases.insert(name, resolved_ty);
-        Ok(())
+
+        match self.aliases.entry(name.clone()) {
+            Entry::Occupied(_) => Err(Error::RedefinedAlias(name)),
+            Entry::Vacant(entry) => {
+                entry.insert(resolved_ty);
+                Ok(())
+            }
+        }
+        // self.aliases.insert(name, resolved_ty);
+        // Ok(())
+    }
+
+    /// Insert a custom function into the global map.
+    ///
+    /// ## Errors
+    ///
+    /// The function has already been defined.
+    pub fn insert_function(
+        &mut self,
+        name: FunctionName,
+        function: CustomFunction,
+    ) -> Result<(), Error> {
+        match self.functions.entry(name.clone()) {
+            Entry::Occupied(_) => Err(Error::FunctionRedefined(name)),
+            Entry::Vacant(entry) => {
+                entry.insert(function);
+                Ok(())
+            }
+        }
     }
 
     /// Insert a parameter into the global map.
@@ -671,25 +698,6 @@ impl Scope {
         )
     }
 
-    /// Insert a custom function into the global map.
-    ///
-    /// ## Errors
-    ///
-    /// The function has already been defined.
-    pub fn insert_function(
-        &mut self,
-        name: FunctionName,
-        function: CustomFunction,
-    ) -> Result<(), Error> {
-        match self.functions.entry(name.clone()) {
-            Entry::Occupied(_) => Err(Error::FunctionRedefined(name)),
-            Entry::Vacant(entry) => {
-                entry.insert(function);
-                Ok(())
-            }
-        }
-    }
-
     /// Get the definition of a custom function.
     pub fn get_function(&self, name: &FunctionName) -> Option<&CustomFunction> {
         self.functions.get(name)

src/error.rs

@@ -428,6 +428,7 @@ pub enum Error {
     ExpressionNotConstant,
     IntegerOutOfBounds(UIntType),
     UndefinedVariable(Identifier),
+    RedefinedAlias(AliasName),
     UndefinedAlias(AliasName),
     VariableReuseInPattern(Identifier),
     WitnessReused(WitnessName),
@@ -546,6 +547,10 @@ impl fmt::Display for Error {
                 f,
                 "Variable `{identifier}` is not defined"
             ),
+            Error::RedefinedAlias(identifier) => write!(
+                f,
+                "Type alias `{identifier}` was defined multiple times"
+            ),
             Error::UndefinedAlias(identifier) => write!(
                 f,
                 "Type alias `{identifier}` is not defined"