Added constness verification for impl fns.

commit-id:9949a206

crates/cairo-lang-semantic/src/diagnostic.rs

@@ -696,6 +696,14 @@ impl DiagnosticEntry for SemanticDiagnostic {
                      `{trait_name}`. The trait function is declared as nopanic."
                 )
             }
+            SemanticDiagnosticKind::PassConstAsNonConst { impl_function_id, trait_id } => {
+                let name = impl_function_id.name(db.upcast());
+                let trait_name = trait_id.name(db.upcast());
+                format!(
+                    "The signature of function `{name}` is incompatible with trait \
+                     `{trait_name}`. The trait function is declared as const."
+                )
+            }
             SemanticDiagnosticKind::PanicableFromNonPanicable => {
                 "Function is declared as nopanic but calls a function that may panic.".into()
             }
@@ -1283,6 +1291,10 @@ pub enum SemanticDiagnosticKind {
         impl_function_id: ImplFunctionId,
         trait_id: TraitId,
     },
+    PassConstAsNonConst {
+        impl_function_id: ImplFunctionId,
+        trait_id: TraitId,
+    },
     PanicableFromNonPanicable,
     PanicableExternFunction,
     PluginDiagnostic(PluginDiagnostic),

crates/cairo-lang-semantic/src/items/imp.rs

@@ -3301,6 +3301,10 @@ fn validate_impl_function_signature(
         diagnostics.report(signature_syntax, PassPanicAsNopanic { impl_function_id, trait_id });
     }
 
+    if concrete_trait_signature.is_const && !signature.is_const {
+        diagnostics.report(signature_syntax, PassConstAsNonConst { impl_function_id, trait_id });
+    }
+
     let expected_ty = inference.rewrite(concrete_trait_signature.return_type).no_err();
     let actual_ty = inference.rewrite(signature.return_type).no_err();