From 0de9de6fd2d0fcdb89dc1abdf58013a91a34b803 Mon Sep 17 00:00:00 2001
From: TomerStarkware <tomer@starkware.co>
Date: Thu, 25 Sep 2025 12:00:22 +0300
Subject: [PATCH] add diagnostic when use star causes cycles

---
 .../cairo-lang-semantic/src/items/tests/use_  | 71 +++++++++++++++++++
 crates/cairo-lang-semantic/src/items/us.rs    | 12 +++-
 2 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/crates/cairo-lang-semantic/src/items/tests/use_ b/crates/cairo-lang-semantic/src/items/tests/use_
index 7f71f6a38f0..d00b7e6b1a9 100644
--- a/crates/cairo-lang-semantic/src/items/tests/use_
+++ b/crates/cairo-lang-semantic/src/items/tests/use_
@@ -178,3 +178,74 @@ error: `self` in `use` items is not allowed for empty path.
  --> lib.cairo:1:6
 use {self, u8};
      ^^^^
+
+//! > ==========================================================================
+
+//! > Use star on a module that was imported with use star.
+
+//! > test_runner_name
+test_function_diagnostics(expect_diagnostics: true)
+
+//! > function
+fn foo() {
+    C::test();
+}
+
+//! > function_name
+foo
+
+//! > module_code
+mod A {
+    pub mod B {
+        pub mod C {
+            pub fn test() {}
+        }
+    }
+}
+use A::*;
+use B::*;
+
+//! > expected_diagnostics
+error[E0006]: Identifier not found.
+ --> lib.cairo:11:5
+    C::test();
+    ^
+
+error: Global `use` item is not supported in `V2023_01` edition.
+ --> lib.cairo:8:8
+use A::*;
+       ^
+
+error[E0006]: Identifier not found.
+ --> lib.cairo:9:5
+use B::*;
+    ^
+
+//! > ==========================================================================
+
+//! > Use star on a non existing module.
+
+//! > test_runner_name
+test_function_diagnostics(expect_diagnostics: true)
+
+//! > function
+fn foo() {
+    C::test();
+}
+
+//! > function_name
+foo
+
+//! > module_code
+use B::*;
+
+//! > expected_diagnostics
+error[E0006]: Identifier not found.
+ --> lib.cairo:3:5
+    C::test();
+    ^
+
+error[E0006]: Identifier not found.
+ --> lib.cairo:1:5
+use B::*;
+    ^
diff --git a/crates/cairo-lang-semantic/src/items/us.rs b/crates/cairo-lang-semantic/src/items/us.rs
index 66de073cedc..67c2602d510 100644
--- a/crates/cairo-lang-semantic/src/items/us.rs
+++ b/crates/cairo-lang-semantic/src/items/us.rs
@@ -374,7 +374,7 @@ pub struct ImportInfo<'db> {
 
 /// Returns the modules that are imported with `use *` and macro calls in the current module.
 /// Query implementation of [UseSemantic::module_imported_modules].
-#[salsa::tracked(returns(ref))]
+#[salsa::tracked(returns(ref),cycle_result=module_imported_modules_cycle)]
 fn module_imported_modules<'db>(
     db: &'db dyn Database,
     _tracked: Tracked,
@@ -430,6 +430,16 @@ fn module_imported_modules<'db>(
     modules
 }
 
+/// Cycle handling for [UseSemantic::module_imported_modules].
+fn module_imported_modules_cycle<'db>(
+    _db: &'db dyn Database,
+    _tracked: Tracked,
+    _module_id: ModuleId<'db>,
+) -> ImportedModules<'db> {
+    Default::default()
+}
+
+
 /// Trait for use-related semantic queries.
 pub trait UseSemantic<'db>: Database {
     /// Private query to compute data about a use.