Consuming a value with a destructuring pattern doesn't end its borrows for drop-check. #145032
Description
I tried this code:
struct Fork<'a>(&'a mut i32); impl Drop for Fork<'_> { fn drop(&mut self) {} } fn parse(mut input: i32) { if let Some(fork) = Some(Fork(&mut input)) { drop(fork); let _x = input; } }I expected the code to compile, but I got the following error:
error[E0503]: cannot use `input` because it was mutably borrowed --> src/lib.rs:10:18 | 8 | if let Some(fork) = Some(Fork(&mut input)) { | ---------------------- | | | | | `input` is borrowed here | a temporary with access to the borrow is created here ... 9 | drop(fork); 10 | let _x = input; | ^^^^^ use of borrowed `input` 11 | }; | - ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `Option<Fork<'_>>` For more information about this error, try `rustc --explain E0503`. I also tried using match instead of if let:
struct Fork<'a>(&'a mut i32); impl Drop for Fork<'_> { fn drop(&mut self) {} } fn parse(mut input: i32) { match Some(Fork(&mut input)) { Some(fork) => { drop(fork); let _x = input; } _ => {} } }I got this error:
error[E0503]: cannot use `input` because it was mutably borrowed --> src/lib.rs:11:22 | 8 | match Some(Fork(&mut input)) { | ---------------------- | | | | | `input` is borrowed here | a temporary with access to the borrow is created here ... ... 11 | let _x = input; | ^^^^^ use of borrowed `input` ... 14 | } | - ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `Option<Fork<'_>>` | help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped | 14 | }; | + For more information about this error, try `rustc --explain E0503`. In either case, adding the semicolon, as indicated in the error, doesn't fix the error.
Minimized from real code by @spikespaz in the community discord.
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Reproducible on the playground with version 1.91.0-nightly (2025-08-05 ec7c02612527d185c379)