RFC: Refactoring internal module variable naming in Rspack output

[chenjiahan]

Summary

This RFC proposes a refinement of the internal module variable naming conventions used in Rspack's generated output.

The goal is to improve readability, reinforce Rspack’s branding, and reduce unnecessary verbosity. The new approach adopts a consistent __rspack_ prefix instead of __webpack_ and __WEBPACK_, shortens excessively long suffix segments, and unifies the naming style using lowercase identifiers.

These names are internal implementation details, so the change is not expected to introduce breaking behavior. We will roll out the adjustments gradually and may revert specific parts if any incompatibility is discovered.

Motivation

Rspack currently uses naming patterns inherited from webpack, for example:

// source code
import shared from './shared.js';

// output code
/* import */ var _shared__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__("./shared.js");

These identifiers are verbose and visually heavy. A cleaner naming scheme makes compiled output easier to understand and debug, and it reinforces clear attribution to Rspack. (See also webpack/webpack#6266)

Proposal

The updated naming rules are:

• Use the unified prefix __rspack_ for all internal variables.
• Shorten compound suffixes such as imported_module or module_reference.
• Use lowercase with underscore separators to improve legibility.
• Omitting trailing underscores.

Examples

// before
/* import */ var _shared__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__("./shared.js");

// after
/* import */ var _shared__rspack_module_0 = __webpack_require__("./shared.js");

All Variables

Here are all the known module internal variable names and their new names:

webpack name	Rspack name
__webpack_require__	__rspack_require
__webpack_exports__	__rspack_exports
__unused_webpack_exports	__rspack_unused_exports
__webpack_module__	__rspack_module
__unused_webpack_module	__rspack_unused_module
__webpack_async_dependencies__	__rspack_async_dependencies
__webpack_handle_async_dependencies__	__rspack_handle_async_dependencies
__webpack_unused_export__	__rspack_unused_export
__webpack_used_export__	__rspack_used_export
__webpack_inlined_export__	__rspack_inlined_export
__webpack_provide_	__rspack_provide_
__webpack_exports_export__	__rspack_exports_export
__webpack_export_target__	__rspack_export_target
__webpack_exports_default__	__rspack_exports_default
__webpack_dirname__	__rspack_dirname
__webpack_fileURLToPath__	__rspack_fileURLToPath
__WEBPACK_EXTERNAL_MODULE_foo__	__rspack_external_foo
__WEBPACK_EXTERNAL_createRequire	__rspack_createRequire
__WEBPACK_EXTERNAL_createRequire_require	__rspack_createRequire_require
__WEBPACK_DEFAULT_EXPORT__	__rspack_default_export
__WEBPACK_NAMESPACE_OBJECT_foo	__rspack_namespace_foo
__WEBPACK_IMPORTED_MODULE_foo	__rspack_import_foo
__WEBPACK_MODULE_REFERENCE_foo	__rspack_module_ref_foo
__WEBPACK_MODULE_DYNAMIC_REFERENCE_foo	__rspack_module_dynamic_ref_foo
__WEBPACK_AMD_REQUIRE_ARRAY__	__rspack_amd_require_array
__WEBPACK_AMD_DEFINE_RESULT__	__rspack_amd_define_result
__WEBPACK_LOCAL_MODULE_foo	__rspack_local_foo
__WEBPACK_REEXPORT_OBJECT__	__rspack_reexport
__WEBPACK_IMPORT_KEY__	__rspack_import_key
__WEBPACK_OUTDATED_DEPENDENCIES__	__rspack_outdated_deps