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Destructuring $derived results in quadratic code size #15996

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theonlypwner opened this issue May 24, 2025 · 0 comments · Fixed by #16015
Closed

Destructuring $derived results in quadratic code size #15996

theonlypwner opened this issue May 24, 2025 · 0 comments · Fixed by #16015

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@theonlypwner
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theonlypwner commented May 24, 2025

Describe the bug

Destructuring $derived with N values results in code size that is quadratic in N. The expected outcome is that it would be linear by destructuring only the value that is actually used.

For example, destructuring 26 values results in code that destructures 26 values being repeated 26 times, resulting in 676 destructurings. See the JS output in the REPL example below.

This issue doesn't occur when destructuring $props.

Reproduction

https://svelte.dev/playground/hello-world?version=5.33.1#H4sIAAAAAAAACrWQzU7DQAyEX2VkcWilUXoPBYkbXBA3DoRD2rh0YbsJWbdpG-Xd0fJXKrVHLpY1tjXjr5dQrlRyuVXva3R16yuMtHKm1VgoC-c1Sv7Ui-2atJcE4c_VTdNkcaPekjYro57S53UwDRYll2mct66x6yIUNpnAxbhWdM6WuKi0dRut0sSroUfT1g0GXOEidXE0vjzMSmJGzImKUGJBvBBLwhGvxBvhiRURiJpoiHeiJSJhxJrYEB2xJXbE_svj236UvJLTdPIbVSimW5Pc2rUOPIPivr5L3zw6Wz6kvCe5nF86DynUR5w-YfwniQPtPwz6cihCP0tlPhQhy7Ii9PvhGM0zxUrnOxcqyReljzp8AC9EOYRgAgAA

System Info

Svelte REPL with version 5.33.1

Severity

annoyance

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