Refactor: Remove unused variable assignments for fallible functions #8247
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Krayt78
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…aritytech#8247) # Description This PR resolves issue paritytech#8236. I recently graduated from PBA, and during one of our sessions, [@shawntabrizi](https://github.com/shawntabrizi) pointed out an important issue related to error handling in Rust. When using let _ = some_fallible_function();, if the result is not followed by a ?, the error is silently swallowed without any warning or compiler feedback. In contrast, if we don’t use let _ = and forget to add a ?, the compiler will correctly emit a warning or error — helping the developer catch the issue early. This behavior can easily lead to bugs going unnoticed and makes error handling less reliable, especially for beginners following examples. ## Integration This PR introduces no functional or logical changes, and therefore can safely be integrated into existing downstream projects without additional adjustments. From my point of view, this issue can be classified as something like `I4-Silent`. ## Review Notes I went through all occurrences of `let _ =` with a fallible function. Some of them return values tagged as `#[must_use]`. In these cases, I retained the underscore operator intentionally _(see: `polkadot/node/core/av-store/src/lib.rs` lines: 1099 & 1108, `polkadot/xcm/xcm-builder/src/currency_adapter.rs` line: 217, `substrate/frame/contracts/src/wasm/mod.rs` line: 360, `substrate/frame/revive/src/wasm/mod.rs` line: 307)_. Co-authored-by: Shawn Tabrizi <[email protected]> Co-authored-by: Bastian Köcher <[email protected]>
castillax
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May 12, 2025
…8247) # Description This PR resolves issue #8236. I recently graduated from PBA, and during one of our sessions, [@shawntabrizi](https://github.com/shawntabrizi) pointed out an important issue related to error handling in Rust. When using let _ = some_fallible_function();, if the result is not followed by a ?, the error is silently swallowed without any warning or compiler feedback. In contrast, if we don’t use let _ = and forget to add a ?, the compiler will correctly emit a warning or error — helping the developer catch the issue early. This behavior can easily lead to bugs going unnoticed and makes error handling less reliable, especially for beginners following examples. ## Integration This PR introduces no functional or logical changes, and therefore can safely be integrated into existing downstream projects without additional adjustments. From my point of view, this issue can be classified as something like `I4-Silent`. ## Review Notes I went through all occurrences of `let _ =` with a fallible function. Some of them return values tagged as `#[must_use]`. In these cases, I retained the underscore operator intentionally _(see: `polkadot/node/core/av-store/src/lib.rs` lines: 1099 & 1108, `polkadot/xcm/xcm-builder/src/currency_adapter.rs` line: 217, `substrate/frame/contracts/src/wasm/mod.rs` line: 360, `substrate/frame/revive/src/wasm/mod.rs` line: 307)_. Co-authored-by: Shawn Tabrizi <[email protected]> Co-authored-by: Bastian Köcher <[email protected]>
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Description
This PR resolves issue #8236.
I recently graduated from PBA, and during one of our sessions, @shawntabrizi pointed out an important issue related to error handling in Rust.
When using let _ = some_fallible_function();, if the result is not followed by a ?, the error is silently swallowed without any warning or compiler feedback.
In contrast, if we don’t use let _ = and forget to add a ?, the compiler will correctly emit a warning or error — helping the developer catch the issue early.
This behavior can easily lead to bugs going unnoticed and makes error handling less reliable, especially for beginners following examples.
Integration
This PR introduces no functional or logical changes, and therefore can safely be integrated into existing downstream projects without additional adjustments.
From my point of view, this issue can be classified as something like
I4-Silent.Review Notes
I went through all occurrences of
let _ =with a fallible function. Some of them return values tagged as#[must_use]. In these cases, I retained the underscore operator intentionally (see:polkadot/node/core/av-store/src/lib.rslines: 1099 & 1108,polkadot/xcm/xcm-builder/src/currency_adapter.rsline: 217,substrate/frame/contracts/src/wasm/mod.rsline: 360,substrate/frame/revive/src/wasm/mod.rsline: 307).