add arg clean

src/args.cpp

@@ -43,7 +43,7 @@ const char *handle_args(int argc, char **argv) {
         auto ret = build::clean();
         if (ret)
             return "CMake clean error!";
-        return "CMake run completed!";
+        return "Cleaned build directory!";
     } else {
         return "Unknown argument!";
     }

src/build.cpp

@@ -48,13 +48,13 @@ int run(int argc, char **argv) {
 }
 
 int clean() {
-    int ret = 0;
+    bool ret = false;
     cmake::CMake cmake(".", true);
     if (fs::exists(cmake.bin_dir)) {
         ret = fs::remove_all(cmake.bin_dir);
         fs::create_directory(cmake.bin_dir);
     }
-    return ret;
+    return !ret;
 }
 
 } // namespace cmkr::build