This PR adjusts the server action transforms to assign proper function names for the generated server reference proxies.
- If the original function has a name, this name is used.
- If a function expression is assigned to a variable, the variable's name is used.
- If an anonymous function expression is assigned to a prop, the prop's name is used.
In addition, this PR simplifies the output for exported functions, avoiding unnecessary `registerServerReference` calls.
It also fixes the source mapping of default exported server actions.
**Before:**
<img width="890" alt="before" src="https://github.com/user-attachments/assets/a3d6a5f8-d48e-474d-8f03-b49306fb704f">
**After:**
<img width="890" alt="after" src="https://github.com/user-attachments/assets/8f332690-6c26-46f1-9eef-7680f47ea578">
Next up, we will do the same for `'use cache'` functions.
This PR adds support for showing the original server sources of server
components and server actions in the browser's developer tools.
To accomplish that, we're building on top of #69190, #70563, and #70564,
in which we prepared the proper generation of the source maps.
This PR completes the feature, by wiring up `findSourceMapURL` (see
https://github.com/facebook/react/pull/30741) with a new dev server
middleware that serves those source map files to the browser.
Another change we had to make is disabling the dead-code elimination of
server actions in client bundles (see #70103), but only in development
mode. This optimization is primarily intended for production bundles, so
the change should not pose a problem.
With that, it's now possible to jump directly into the server sources
from the browser's dev tools, e.g. for component stacks of server logs
that are replayed in the browser, or when inspecting server action props
in the React DevTools.
Sebastian "Sebbie" Silbermann