refactor(encoding): remove as casts#281
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mxinden merged 1 commit intoprometheus:masterfrom Sep 2, 2025
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Also created jalil-salame#1 as a follow up (adding |
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Thanks for the fix! Good work.
Mind adding a changelog entry in CHANGELOG.md? If it doesn't exist yet, you can add [0.24.1] section.
There was a bug in the `impl EncodeGaugeValue for u64` implementation due to the `as i64` cast. The implementation only checked if `self == u64::MAX`, this is wrong since `u64::MAX` is not the only value that cannot be represented by an `i64`. The range of values is actually `self > i64::MAX`. `u64::MAX == 2^64 - 1` whereas `i64::MAX == 2^63 - 1`, this means there are `2^63` `u64` values that are not representable by an `i64`, not just `i64::MAX`. Delegating the checks to `i64::try_from(self)` ensures the logic is right. For this reason I also switched the rest of the implementations to use `N::from` instead of `as N` since the `N::from` function is only implemented for types whose conversion is infallible, this guarantees no such issues will ever happen. The only `as` cast left is `u64 as f64` in `EncodeExemplarValue`, this is not possible to remove since there is no `impl TryFrom<u64> for f64`. Signed-off-by: Jalil David Salamé Messina <[email protected]>
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Done! |
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There was a bug in the
impl EncodeGaugeValue for u64implementation due to theas i64cast.The implementation only checked if
self == u64::MAX, this is wrong sinceu64::MAXis not the only value that cannot be represented by ani64.The range of values is actually
self > i64::MAX.u64::MAX == 2^64 - 1whereasi64::MAX == 2^63 - 1, this means there are2^63u64values that are not representable by ani64, not justi64::MAX. Delegating the checks toi64::try_from(self)ensures the logic is right. For this reason I also switched the rest of the implementations to useN::frominstead ofas Nsince theN::fromfunction is only implemented for types whose conversion is infallible, this guarantees no such issues will ever happen.The only
ascast left isu64 as f64inEncodeExemplarValue, this is not possible to remove since there is noimpl TryFrom<u64> for f64.