fix #480

Author: CppCXY

crates/emmylua_code_analysis/src/compilation/analyzer/flow/bind_analyze/stats.rs

@@ -307,6 +307,8 @@ pub fn bind_if_stat(binder: &mut FlowBinder, if_stat: LuaIfStat, current: FlowId
             let block_id = bind_block(binder, else_block, else_label);
             binder.add_antecedent(post_if_label, block_id);
         }
+    } else {
+        binder.add_antecedent(post_if_label, else_label);
     }
 
     finish_flow_label(binder, post_if_label, else_label)

crates/emmylua_code_analysis/src/compilation/test/flow.rs

@@ -802,4 +802,24 @@ end
         let res_desc = ws.humanize_type(res);
         assert_eq!(res_desc, "(string[]|string)");
     }
+
+    #[test]
+    fn test_issue_480() {
+        let mut ws = VirtualWorkspace::new_with_init_std_lib();
+
+        ws.check_code_for(
+            DiagnosticCode::UnnecessaryAssert,
+            r#"
+            --- @param a integer?
+            --- @param c boolean
+            function foo(a, c)
+                if c then
+                    a = 1
+                end
+
+                assert(a)
+            end
+            "#,
+        );
+    }
 }

crates/emmylua_code_analysis/src/semantic/infer/narrow/condition_flow/binary_flow.rs

@@ -156,13 +156,7 @@ fn maybe_type_guard_binary(
         return Ok(ResultTypeOrContinue::Continue);
     };
 
-    let LuaExpr::NameExpr(name_expr) = arg else {
-        return Ok(ResultTypeOrContinue::Continue);
-    };
-
-    let Some(maybe_var_ref_id) =
-        get_var_expr_var_ref_id(db, cache, LuaExpr::NameExpr(name_expr.clone()))
-    else {
+    let Some(maybe_var_ref_id) = get_var_expr_var_ref_id(db, cache, arg) else {
         // If we cannot find a reference declaration ID, we cannot narrow it
         return Ok(ResultTypeOrContinue::Continue);
     };