From 10889700d1e587c2ff5544efeb7f98448a365057 Mon Sep 17 00:00:00 2001
From: Zuhaitz Méndez Fernández de Aránguiz <zuhaitz@debian>
Date: Mon, 26 Jan 2026 00:07:40 +0000
Subject: Error added for #125

---
 src/parser/parser_decl.c   | 7 +++++++
 src/parser/parser_struct.c | 6 ++++++
 2 files changed, 13 insertions(+)

diff --git a/src/parser/parser_decl.c b/src/parser/parser_decl.c
index c5df863..48077e1 100644
--- a/src/parser/parser_decl.c
+++ b/src/parser/parser_decl.c
@@ -56,6 +56,13 @@ ASTNode *parse_function(ParserContext *ctx, Lexer *l, int is_async)
                 strcat(buf, ",");
             }
             strcat(buf, s);
+            
+            // Check for shadowing
+            if (is_known_generic(ctx, s))
+            {
+                zpanic_at(gt, "Generic parameter '%s' shadows an existing generic parameter", s);
+            }
+            
             free(s);
 
             if (lexer_peek(l).type == TOK_COMMA)
diff --git a/src/parser/parser_struct.c b/src/parser/parser_struct.c
index 17d8e93..b7dec32 100644
--- a/src/parser/parser_struct.c
+++ b/src/parser/parser_struct.c
@@ -142,6 +142,12 @@ ASTNode *parse_trait(ParserContext *ctx, Lexer *l)
     n_node->trait.methods = methods;
     n_node->trait.generic_params = generic_params;
     n_node->trait.generic_param_count = generic_count;
+    
+    if (generic_count > 0)
+    {
+        ctx->known_generics_count -= generic_count;
+    }
+
     register_trait(name);
     return n_node;
 }
-- 
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