Bug report

What is the current behavior?
If the current behavior is a bug, please provide the steps to reproduce.

See reproduction: https://github.com/Hypnosphi/webpack-5-repro

Here’s the output with invalid syntax:

// CONCATENATED MODULE: ./src/b.js
function b_noop() {}

function B({foo = noop: b_noop}) {}

What is the expected behavior?

// CONCATENATED MODULE: ./src/b.js
function b_noop() {}

function B({foo = b_noop}) {}

Other relevant information:
webpack version: 5.24.0
Node.js version: 12.20.2
Operating System: Linux, macOS
Additional tools: no