fix: foreach sentinel end was not done in JIT code

Author: giann

src/Jit.zig

@@ -5398,6 +5398,15 @@ fn generateForEach(self: *Self, node: Ast.Node.Index) Error!?m.MIR_op_t {
     const key_ptr = try self.buildStackPtr(2);
     const value_ptr = try self.buildStackPtr(1);
 
+    if (self.state.?.ast_node != node and iterable_type_def.?.def_type == .Map) {
+        // Mirror bytecode foreach setup: use the sentinel as the internal map
+        // iteration marker so a real `null` key does not restart the loop.
+        self.MOV(
+            try self.LOAD(key_ptr),
+            m.MIR_new_uint_op(self.ctx, Value.Sentinel.val),
+        );
+    }
+
     const cond_label = m.MIR_new_label(self.ctx);
     const out_label = m.MIR_new_label(self.ctx);
 

src/buzz_api.zig

@@ -1473,7 +1473,9 @@ export fn bz_rangeNext(range_value: v.Value, index_slot: v.Value) callconv(.c) v
 
 export fn bz_mapNext(map_value: v.Value, key: *v.Value) callconv(.c) v.Value {
     const map = o.ObjMap.cast(map_value.obj()).?;
-    const next_key = map.rawNext(if (key.isNull()) v.Value.Sentinel else key.*);
+    // Map iteration uses sentinel as the internal start/end marker so real
+    // `null` keys remain iterable for both bytecode and JIT/native callers.
+    const next_key = map.rawNext(key.*);
     key.* = next_key;
 
     if (!next_key.isSentinel()) {

src/lib/buzz_api.zig

@@ -36,6 +36,7 @@ const TagNull: Tag = 2;
 const TagVoid: Tag = 3;
 const TagObj: Tag = 4;
 const TagError: Tag = 5;
+const TagSentinel: Tag = 6;
 
 /// Most significant bit.
 const SignMask: u64 = 1 << 63;
@@ -55,6 +56,7 @@ const IntegerMask: u64 = TaggedValueMask | (@as(u64, TagInteger) << 49);
 const NullMask: u64 = TaggedValueMask | (@as(u64, TagNull) << 32);
 const VoidMask: u64 = TaggedValueMask | (@as(u64, TagVoid) << 32);
 const ErrorMask: u64 = TaggedValueMask | (@as(u64, TagError) << 32);
+const SentinelMask: u64 = TaggedValueMask | (@as(u64, TagSentinel) << 32);
 
 const TagMask: u32 = (1 << 3) - 1;
 const TaggedPrimitiveMask = TaggedValueMask | (@as(u64, TagMask) << 32) | IntegerMask;
@@ -68,6 +70,7 @@ pub const Value = extern struct {
     pub const False = Value{ .val = FalseMask };
     // We only need this so that an NativeFn can see the error returned by its raw function
     pub const Error = Value{ .val = ErrorMask };
+    pub const Sentinel = Value{ .val = SentinelMask };
 
     pub fn fromBoolean(val: bool) Value {
         return if (val) True else False;
@@ -121,6 +124,10 @@ pub const Value = extern struct {
         return self.val == ErrorMask;
     }
 
+    pub fn isSentinel(self: Value) bool {
+        return self.val == SentinelMask;
+    }
+
     pub fn boolean(self: Value) bool {
         return self.val == TrueMask;
     }

src/lib/buzz_http.zig

@@ -109,9 +109,9 @@ fn innerHttpClientSend(ctx: *api.NativeCtx) !c_int {
     const header_values = ctx.vm.bz_peek(1);
     var headers = std.ArrayList(std.http.Header).empty;
     errdefer if (!request_initialized) headers.deinit(api.VM.allocator);
-    var next_header_key = api.Value.Null;
+    var next_header_key = api.Value.Sentinel;
     var next_header_value = header_values.bz_mapNext(&next_header_key);
-    while (next_header_key.val != api.Value.Null.val) : (next_header_value = header_values.bz_mapNext(&next_header_key)) {
+    while (next_header_key.val != api.Value.Sentinel.val) : (next_header_value = header_values.bz_mapNext(&next_header_key)) {
         var key_len: usize = 0;
         const key = next_header_key.bz_valueToString(&key_len) orelse return error.OutOfMemory;
         var value_len: usize = 0;

src/obj.zig

@@ -3510,12 +3510,12 @@ pub const ObjMap = struct {
 
         // Sentinel is the internal start/end marker so real `null` keys remain iterable.
         if (key.isSentinel()) {
-            return if (map_keys.len > 0) map_keys[0] else Value.Sentinel;
+            return if (map_keys.len > 0) map_keys[0] else .Sentinel;
         }
 
         const index: usize = self.map.getIndex(key).?;
 
-        return if (index < map_keys.len - 1) map_keys[index + 1] else Value.Sentinel;
+        return if (index < map_keys.len - 1) map_keys[index + 1] else .Sentinel;
     }
 
     pub fn deinit(self: *Self, allocator: Allocator) void {