# Compile-time faillable expression

**URL:** <https://internals.rust-lang.org/t/compile-time-faillable-expression/21985>\
**Category:** language design\
**Created:** [December 7, 2024, 10:44am UTC](https://internals.rust-lang.org/t/compile-time-faillable-expression/21985 "2024-12-07T10:44:39Z")\
**Posts on this page:** 1\
**Showing post:** 11

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**Author:** ![kpreid](https://sea2.discourse-cdn.com/flex002/user_avatar/internals.rust-lang.org/kpreid/32/8484_2.png) [@kpreid](https://internals.rust-lang.org/u/kpreid)\
**Post date:** [December 9, 2024, 4:25pm UTC](https://internals.rust-lang.org/t/compile-time-faillable-expression/21985/11 "2024-12-09T16:25:36Z")

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Posted: [Pre-RFC: `?` operator in constants](https://internals.rust-lang.org/t/pre-rfc-operator-in-constants/21996)

“Pretty short”, I said. Well, the definition is much shorter than the rationale.

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