Using spread syntax '{...rest }' with props doesnt work correctly!

[Tichss]

Describe the bug

There is a simple example:

<script lang="ts">
    let value = $state();
</script>

<div>Value: {value}</div>
<div>Typeof value: {typeof value}</div>

<input {value} oninput={(e) => (value = e.target.value)} type="text" />
<input {value} oninput={(e) => (value = e.target.value)} type="text" {...{}} /> <!-- {...{}} diff -->

<button onclick={() => (value = '')}>empty string</button>
<button onclick={() => (value = undefined)}>undefined</button>
<button onclick={() => (value = null)}>null</button>

The 2 inputs differ only in the spread operator.
In theory, should both be the same? not?

However, there are a few interesting things when updating the value:

• set to empty string : both input updated correctly ✔
• set to undefined : 1. input get value as empty string ✔, 2. input value dont updated ❌
• set to null : same as undefined ❌

try it here:
https://svelte.dev/playground/7a327186482347e688080339ea4a23a9?version=5.19.9

Reproduction

https://svelte.dev/playground/7a327186482347e688080339ea4a23a9?version=5.19.9

Logs

System Info

System:
    OS: Windows 10 10.0.19045
    CPU: (8) x64 Intel(R) Core(TM) i5-8259U CPU @ 2.30GHz
    Memory: 3.41 GB / 15.87 GB
  Binaries:
    Node: 20.11.1 - C:\Program Files\nodejs\node.EXE     
    npm: 8.19.2 - C:\Program Files\nodejs\npm.CMD        
  Browsers:
    Edge: Chromium (127.0.2651.74)
    Internet Explorer: 11.0.19041.4355

Severity

annoyance

[paoloricciuti]

Sorry but I'm not seeing this behavior in your repl...the input stays empty with all three buttons.

[Tichss]

try to update any input with same value.

eg:
type to input 1 or 2: asd
press button empty string ✔
type to input 1 or 2: asd
press button empty undefined ❌

[paoloricciuti]

Oh gotcha... thanks

[adiguba]

I made a PR : the problem come from set_attributes().

And input's checkbox is also concerned by this :

https://svelte.dev/playground/hello-world?version=5.19.9#H4sIAAAAAAAACq1Sy07EMAz8FRNx2Eq0vZc2EuIT4EY59OHdrTYkUeOsFlX9d5ym-0DiABK5OB7PjO0ok9DNB4pCvNgRmx5avxMPYjsodKJ4mwR92lANAOMr98nazB1RUcDaxuFPeGc0oSa2EaXrxsESqEbvqlqQq4WsNfBRSNDtsTtgDxXcO2oIN8ljrcs8apjHST8c5XOkFTCtgrnMA76WX3lQsz2bMYu-ARcy0wdtPV1twOgFqaYNJlBJ2Bwb5ZHnwYyacYeUrdRkhuDKKyxAa061gFz-u-WUZdk0z9H6Lk0vQJrGDVpPZDR36dTQHbhLbHJ9SRo9JrNcgTKPAvkbqdc9bgcdRpOX-58ctFeKxSHc6FhpQ6CFCLRHOK-M7iHkGrzDpRBFDsrO9Hg7xZKDGddKbLFcw5exkv8d4YlEER5gfp-_AH7dU_LfAgAA