From ad276fffb31c77135d802db6f460e1e78aeef974 Mon Sep 17 00:00:00 2001
From: Ben Bridle <ben@derelict.engineering>
Date: Fri, 4 Jul 2025 21:39:00 +1200
Subject: Raise error if an instruction name is redefined

---
 src/stages/semantic.rs        | 15 ++++++++++++++-
 src/stages/semantic_tokens.rs |  3 +++
 2 files changed, 17 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/stages/semantic.rs b/src/stages/semantic.rs
index 909659d..dc9709e 100644
--- a/src/stages/semantic.rs
+++ b/src/stages/semantic.rs
@@ -1,15 +1,24 @@
 use crate::*;
 
+use std::str::FromStr;
+
 use indexmap::{IndexMap, IndexSet};
 
 
 pub fn parse_semantic(syntactic: Vec<Tracked<SyntacticToken>>) -> Result<Program, Vec<Tracked<SemanticError>>> {
+    let mut errors = Vec::new();
+
     // Record all label definitions and macro names up front.
     let mut definitions = IndexMap::new();
     let mut macro_names = IndexSet::new();
     for token in &syntactic {
         match &token.value {
             SyntacticToken::LabelDefinition(name) => {
+                // Check if identifier is reserved.
+                if Instruction::from_str(&name).is_ok() {
+                    let error = SemanticError::ReservedIdentifier(name.to_string());
+                    errors.push(Tracked::from(error, token.source.clone()));
+                }
                 // Use a fake index for now.
                 let definition = Definition::new(0, DefinitionVariant::LabelDefinition);
                 let tracked = Tracked::from(definition, token.source.clone());
@@ -19,6 +28,11 @@ pub fn parse_semantic(syntactic: Vec<Tracked<SyntacticToken>>) -> Result<Program
             }
             SyntacticToken::MacroDefinition(definition) => {
                 let name = &definition.name;
+                // Check if identifier is reserved.
+                if Instruction::from_str(&name).is_ok() {
+                    let error = SemanticError::ReservedIdentifier(name.to_string());
+                    errors.push(Tracked::from(error, name.source.clone()));
+                }
                 if !macro_names.insert(name.clone()) {
                     unreachable!("Uncaught duplicate macro definition '{name}'")
                 }
@@ -29,7 +43,6 @@ pub fn parse_semantic(syntactic: Vec<Tracked<SyntacticToken>>) -> Result<Program
 
     // Convert syntactic tokens to semantic tokens.
     let mut tokens: Vec<Tracked<SemanticToken>> = Vec::new();
-    let mut errors = Vec::new();
     let mut stack = Vec::new();
 
     for syn_token in syntactic {
diff --git a/src/stages/semantic_tokens.rs b/src/stages/semantic_tokens.rs
index fc454be..c735828 100644
--- a/src/stages/semantic_tokens.rs
+++ b/src/stages/semantic_tokens.rs
@@ -49,6 +49,7 @@ pub enum SemanticToken {
 
 pub enum SemanticError {
     InvocationBeforeDefinition,
+    ReservedIdentifier(String),
 }
 
 
@@ -64,6 +65,8 @@ 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);
 }
-- 
cgit v1.2.3-70-g09d2