Fixed loop inside loop issue. (#5441)

crates/cairo-lang-lowering/src/lower/mod.rs

@@ -315,7 +315,7 @@ pub fn lower_loop_function(
     loop_expr_id: semantic::ExprId,
 ) -> Maybe<FlatLowered> {
     let mut ctx = LoweringContext::new(encapsulating_ctx, function_id, loop_signature.clone())?;
-    ctx.current_loop_expr_id = Some(loop_expr_id);
+    let old_loop_expr_id = std::mem::replace(&mut ctx.current_loop_expr_id, Some(loop_expr_id));
 
     // Initialize builder.
     let root_block_id = alloc_empty_block(&mut ctx);
@@ -369,6 +369,7 @@ pub fn lower_loop_function(
 
         Ok(root_block_id)
     })();
+    ctx.current_loop_expr_id = old_loop_expr_id;
 
     let blocks = root_ok
         .map(|_| ctx.blocks.build().expect("Root block must exist."))
@@ -1252,9 +1253,10 @@ fn lower_expr_loop(
     encapsulating_ctx.lowerings.insert(loop_expr_id, lowered);
 
     ctx.encapsulating_ctx = Some(encapsulating_ctx);
-    ctx.current_loop_expr_id = Some(loop_expr_id);
-
-    call_loop_func(ctx, loop_signature, builder, loop_expr_id, stable_ptr.untyped())
+    let old_loop_expr_id = std::mem::replace(&mut ctx.current_loop_expr_id, Some(loop_expr_id));
+    let call = call_loop_func(ctx, loop_signature, builder, loop_expr_id, stable_ptr.untyped());
+    ctx.current_loop_expr_id = old_loop_expr_id;
+    call
 }
 
 /// Adds a call to an inner loop-generated function.

tests/bug_samples/issue5438.cairo

@@ -0,0 +1,27 @@
+#[inline(never)]
+fn foo(mut x: i8, mut y: i8) -> i8 {
+    loop {
+        match x {
+            0 => {
+                // A loop before continue - bug would cause the continue to call this loop.
+                while y < 100 {
+                    y += 1;
+                };
+                x += 1;
+            },
+            1 => {
+                x -= 2;
+                continue;
+            },
+            _ => { x -= 2; },
+        }
+        if x < 0 {
+            break y;
+        }
+    }
+}
+
+#[test]
+fn loop_of_loop() -> i8 {
+    foo(10, 10)
+}

tests/bug_samples/lib.cairo

@@ -41,6 +41,7 @@ mod issue4380;
 mod issue4897;
 mod issue4937;
 mod issue5411;
+mod issue5438;
 mod loop_break_in_match;
 mod loop_only_change;
 mod partial_param_local;