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coord: ranged1d: fix irrefutable if let warning#667

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AaronErhardt merged 1 commit intoplotters-rs:masterfrom10ne1:dev/aratiu/fix-irrefutable-let-warn

Mar 27, 2025

Merged

coord: ranged1d: fix irrefutable if let warning#667

AaronErhardt merged 1 commit intoplotters-rs:masterfrom10ne1:dev/aratiu/fix-irrefutable-let-warn

Mar 27, 2025

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10ne1 commentedDec 21, 2024

I keep getting this annoying warning with rust 1.83:

warning: irrefutableif let pattern
--> plotters/src/coord/ranged1d/types/numeric.rs:29:20
|
29 | if let Ok(index) = Self::ValueType::try_from(index) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
365 | impl_discrete_trait!(RangedCoordusize);
| -------------------------------------- in this macro invocation
|
= note: this pattern will always match, so theif let is useless
= help: consider replacing theif let with alet
= note:#[warn(irrefutable_let_patterns)] on by default
= note: this warning originates in the macroimpl_discrete_trait (in Nightly builds, run with -Z macro-backtrace for more info)

This is because the conversion of usize to ValueType always passes, so we don't need the try_from().

The problem with this operation is not the conversion which always succeeds, instead it is the potential overflows, so we use checked_add() which returns None if the addition fails.

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booti386 commentedMar 7, 2025

Thanks for your PR.
However, i will complete your analysis. The macroimpl_discrete_trait that you patched is used several times at the bottom of the file, to implementDiscreteRanged for all the differentRangedCoord* types.
The specific call that produces the warning that you're citing isimpl_discrete_trait!(RangedCoordusize);, because we convert usize to usize, which always succeed. However it is not always true for the other calls, e.g.impl_discrete_trait!(RangedCoordu32); when usize is bigger than u32 on the target architecture.
So I suggest you modify your patch slightly (and don't bother adding me as a co-author, I don't care):

fnfrom_index(&self,index:usize) ->Option<Self::ValueType>{Self::ValueType::try_from(index).ok().and_then(|index|self.0.checked_add(index))}

coord: ranged1d: fix irrefutable if let warning

dd806bd

I keep getting this annoying warning with rust 1.83:warning: irrefutable `if let` pattern   --> plotters/src/coord/ranged1d/types/numeric.rs:29:20    |29  |                 if let Ok(index) = Self::ValueType::try_from(index) {    |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^...365 | impl_discrete_trait!(RangedCoordusize);    | -------------------------------------- in this macro invocation    |    = note: this pattern will always match, so the `if let` is useless    = help: consider replacing the `if let` with a `let`    = note: `#[warn(irrefutable_let_patterns)]` on by default    = note: this warning originates in the macro `impl_discrete_trait` (in Nightly builds, run with -Z macro-backtrace for more info)This is because the conversion of usize to ValueType alwayspasses, so we don't need the try_from() in all cases.An additional problem are potential overflows so we usechecked_add() which returns None if the addition fails,thus also avoiding the irrefutable let pattern while alsoprotecting against overflows.Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>