1 files changed, 6 insertions, 3 deletions
diff --git a/src/stages/semantic_tokens.rs b/src/stages/semantic_tokens.rs
index fe49c26..c735828 100644
--- a/src/stages/semantic_tokens.rs
+++ b/src/stages/semantic_tokens.rs
@@ -1,10 +1,10 @@
 use crate::*;
 
-use std::collections::HashMap;
+use indexmap::IndexMap;
 
 
 pub struct Program {
-    pub definitions: HashMap<String, Tracked<Definition>>,
+    pub definitions: IndexMap<String, Tracked<Definition>>,
     pub tokens: Vec<Tracked<SemanticToken>>,
 }
 
@@ -49,6 +49,7 @@ pub enum SemanticToken {
 
 pub enum SemanticError {
     InvocationBeforeDefinition,
+    ReservedIdentifier(String),
 }
 
 
@@ -64,12 +65,14 @@ fn report_semantic_error(error: &Tracked<SemanticError>, source_code: &str) {
     let message = match &error.value {
         SemanticError::InvocationBeforeDefinition =>
             "Macro cannot be invoked before it has been defined",
+        SemanticError::ReservedIdentifier(name) =>
+            &format!("Identifier '{name}' is reserved for a built-in instruction"),
     };
     report_source_issue(LogLevel::Error, &context, message);
 }
 
 
-pub fn print_semantic_token(i: usize, token: &SemanticToken, definitions: &HashMap<String, Tracked<Definition>>) {
+pub fn print_semantic_token(i: usize, token: &SemanticToken, definitions: &IndexMap<String, Tracked<Definition>>) {
     match token {
         SemanticToken::Literal(value) => indent!(i, "Literal({value})"),
         SemanticToken::Pad(value) => indent!(i, "Pad({value})"),