# \[Pre-RFC\] Implicit number type widening

**URL:** <https://internals.rust-lang.org/t/pre-rfc-implicit-number-type-widening/10432>\
**Category:** Uncategorized\
**Created:** [June 19, 2019, 8:12pm UTC](https://internals.rust-lang.org/t/pre-rfc-implicit-number-type-widening/10432 "2019-06-19T20:12:01Z")\
**Posts on this page:** 1\
**Showing post:** 121

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**Author:** ![Tom-Phinney](https://sea2.discourse-cdn.com/flex002/user_avatar/internals.rust-lang.org/tom-phinney/32/3299_2.png) [@Tom-Phinney](https://internals.rust-lang.org/u/Tom-Phinney)\
**Post date:** [October 4, 2019, 3:41pm UTC](https://internals.rust-lang.org/t/pre-rfc-implicit-number-type-widening/10432/121 "2019-10-04T15:41:59Z")

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I view this as a generic hazard of transmuting between representations, which is what is happening here: `f32` transmuted to `u32` and vice versa, and likewise between `f64` and `u64`. The same issue can occur if an `i32` is transmuted to a `u32` and then widened to a `u64` before being transmuted back to an `i64`.

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_[View the full topic](https://internals.rust-lang.org/t/pre-rfc-implicit-number-type-widening/10432)._