From 010dbc96ffbb98a04d0f976d4659f9db6a76ff53 Mon Sep 17 00:00:00 2001
From: bQUARKz <bquarkz@gmail.com>
Date: Wed, 4 Feb 2026 19:11:05 +0000
Subject: [PATCH] pr 04.b

---
 .../src/analysis/symbols/mod.rs               | 83 +++++++++++++++++++
 1 file changed, 83 insertions(+)

diff --git a/crates/prometeu-compiler/src/analysis/symbols/mod.rs b/crates/prometeu-compiler/src/analysis/symbols/mod.rs
index 7b7b194b..ab238950 100644
--- a/crates/prometeu-compiler/src/analysis/symbols/mod.rs
+++ b/crates/prometeu-compiler/src/analysis/symbols/mod.rs
@@ -1,6 +1,8 @@
+use crate::common::diagnostics::{Diagnostic, DiagnosticLevel};
 use crate::common::spans::Span;
 use prometeu_analysis::NameId;
 use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize, Deserialize)]
 pub struct SymbolId(pub u32);
@@ -17,6 +19,13 @@ pub enum SymbolKind {
     Local,
 }
 
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize, Deserialize)]
+pub enum Namespace {
+    Type,
+    Value,
+    Service,
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct Symbol {
     pub name: NameId,
@@ -31,6 +40,18 @@ pub struct SymbolArena {
     pub symbols: Vec<Symbol>,
 }
 
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
+pub struct DefKey {
+    pub module: u32,
+    pub name: NameId,
+    pub namespace: Namespace,
+}
+
+#[derive(Debug, Default, Clone)]
+pub struct DefIndex {
+    symbols: HashMap<DefKey, SymbolId>,
+}
+
 impl SymbolArena {
     pub fn new() -> Self {
         Self { symbols: Vec::new() }
@@ -47,6 +68,32 @@ impl SymbolArena {
     }
 }
 
+impl DefIndex {
+    pub fn new() -> Self {
+        Self {
+            symbols: HashMap::new(),
+        }
+    }
+
+    pub fn insert_symbol(&mut self, key: DefKey, symbol_id: SymbolId) -> Result<(), Diagnostic> {
+        if self.symbols.contains_key(&key) {
+            return Err(Diagnostic {
+                level: DiagnosticLevel::Error,
+                code: Some("E_RESOLVE_DUPLICATE_SYMBOL".to_string()),
+                message: "Duplicate symbol in the same module and namespace".to_string(),
+                span: None,
+            });
+        }
+
+        self.symbols.insert(key, symbol_id);
+        Ok(())
+    }
+
+    pub fn get(&self, key: DefKey) -> Option<SymbolId> {
+        self.symbols.get(&key).copied()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -82,4 +129,40 @@ mod tests {
         assert_eq!(arena.get(id).module, symbol.module);
         assert_eq!(arena.get(id).decl_span, symbol.decl_span);
     }
+
+    #[test]
+    fn def_index_duplicate_in_same_namespace_errors() {
+        let mut index = DefIndex::new();
+        let key = DefKey {
+            module: 1,
+            name: NameId(10),
+            namespace: Namespace::Type,
+        };
+
+        assert!(index.insert_symbol(key, SymbolId(0)).is_ok());
+        let err = index.insert_symbol(key, SymbolId(1)).unwrap_err();
+
+        assert_eq!(err.code, Some("E_RESOLVE_DUPLICATE_SYMBOL".to_string()));
+    }
+
+    #[test]
+    fn def_index_allows_same_name_in_different_namespace() {
+        let mut index = DefIndex::new();
+        let name = NameId(11);
+        let type_key = DefKey {
+            module: 2,
+            name,
+            namespace: Namespace::Type,
+        };
+        let value_key = DefKey {
+            module: 2,
+            name,
+            namespace: Namespace::Value,
+        };
+
+        assert!(index.insert_symbol(type_key, SymbolId(0)).is_ok());
+        assert!(index.insert_symbol(value_key, SymbolId(1)).is_ok());
+        assert_eq!(index.get(type_key), Some(SymbolId(0)));
+        assert_eq!(index.get(value_key), Some(SymbolId(1)));
+    }
 }
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