CLI error handling

rust_compiler/libs/parser/src/lib.rs

@@ -1589,7 +1589,7 @@ impl<'a> Parser<'a> {
         } else {
             // we need to rewind our tokenizer to our previous location
             self.tokenizer.seek(SeekFrom::Current(
-                self.tokenizer.loc() - current_token_index,
+                current_token_index - self.tokenizer.loc(),
             ))?;
             let syscall = self.spanned(|p| p.syscall())?;
 

rust_compiler/libs/parser/src/test/mod.rs

@@ -149,6 +149,23 @@ fn test_const_hash_expression() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn test_const_hash() -> Result<()> {
+    // This test explicitly validates the tokenizer rewind logic.
+    // When parsing "const h = hash(...)", the parser:
+    // 1. Consumes "const", identifier, "="
+    // 2. Attempts to parse "hash(...)" as a literal - this fails
+    // 3. Must rewind the tokenizer to before "hash"
+    // 4. Then parse it as a syscall
+    // If the rewind offset is wrong (e.g., positive instead of negative),
+    // the tokenizer will be at the wrong position and parsing will fail.
+    let expr = parser!(r#"const h = hash("ComponentComputer")"#)
+        .parse()?
+        .unwrap();
+    assert_eq!(r#"(const h = hash("ComponentComputer"))"#, expr.to_string());
+    Ok(())
+}
+
 #[test]
 fn test_negative_literal_const() -> Result<()> {
     let expr = parser!(r#"const i = -123"#).parse()?.unwrap();

rust_compiler/libs/tokenizer/src/lib.rs

@@ -145,8 +145,20 @@ impl<'a> TokenizerBuffer<'a> {
         use Ordering::*;
         match seek_to_int.cmp(&0) {
             Greater => {
-                let mut tokens = Vec::with_capacity(seek_to_int as usize);
-                for _ in 0..seek_to_int {
+                let mut seek_remaining = seek_to_int as usize;
+
+                // First, consume tokens from the buffer (peeked but not yet consumed)
+                while seek_remaining > 0 && !self.buffer.is_empty() {
+                    if let Some(token) = self.buffer.pop_front() {
+                        self.history.push_back(token);
+                        seek_remaining -= 1;
+                        self.index += 1;
+                    }
+                }
+
+                // Then get tokens from tokenizer if needed
+                let mut tokens = Vec::with_capacity(seek_remaining);
+                for _ in 0..seek_remaining {
                     if let Some(token) = self.tokenizer.next_token()? {
                         tokens.push(token);
                     } else {
@@ -157,6 +169,7 @@ impl<'a> TokenizerBuffer<'a> {
                     }
                 }
                 self.history.extend(tokens);
+                self.index += seek_remaining as i64;
             }
             Less => {
                 let seek_to = seek_to_int.unsigned_abs() as usize;