[regression] println borrow check errors #96434
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bors
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May 1, 2022
…lacrum Make [e]println macros eagerly drop temporaries (for backport) This PR extracts the subset of rust-lang#96455 which is only the parts necessary for fixing the 1.61-beta regressions in rust-lang#96434. My larger PR rust-lang#96455 contains a few other changes relative to the pre-rust-lang#94868 behavior; those are not necessary to backport into 1.61. argument position | before rust-lang#94868 | after rust-lang#94868 | after this PR --- |:---:|:---:|:---: `write!($tmp, "…", …)` | :rage: | :rage: | :rage: `write!(…, "…", $tmp)` | :rage: | :rage: | :rage: `writeln!($tmp, "…", …)` | :rage: | :rage: | :rage: `writeln!(…, "…", $tmp)` | :rage: | :rage: | :rage: `print!("…", $tmp)` | :rage: | :rage: | :rage: `println!("…", $tmp)` | :smiley_cat: | :rage: | :smiley_cat: `eprint!("…", $tmp)` | :rage: | :rage: | :rage: `eprintln!("…", $tmp)` | :smiley_cat: | :rage: | :smiley_cat: `panic!("…", $tmp)` | :smiley_cat: | :smiley_cat: | :smiley_cat:
ehuss
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May 4, 2022
…lacrum Make [e]println macros eagerly drop temporaries (for backport) This PR extracts the subset of rust-lang#96455 which is only the parts necessary for fixing the 1.61-beta regressions in rust-lang#96434. My larger PR rust-lang#96455 contains a few other changes relative to the pre-rust-lang#94868 behavior; those are not necessary to backport into 1.61. argument position | before rust-lang#94868 | after rust-lang#94868 | after this PR --- |:---:|:---:|:---: `write!($tmp, "…", …)` | :rage: | :rage: | :rage: `write!(…, "…", $tmp)` | :rage: | :rage: | :rage: `writeln!($tmp, "…", …)` | :rage: | :rage: | :rage: `writeln!(…, "…", $tmp)` | :rage: | :rage: | :rage: `print!("…", $tmp)` | :rage: | :rage: | :rage: `println!("…", $tmp)` | :smiley_cat: | :rage: | :smiley_cat: `eprint!("…", $tmp)` | :rage: | :rage: | :rage: `eprintln!("…", $tmp)` | :smiley_cat: | :rage: | :smiley_cat: `panic!("…", $tmp)` | :smiley_cat: | :smiley_cat: | :smiley_cat:
GuillaumeGomez
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May 12, 2022
Make write/print macros eagerly drop temporaries This PR fixes the 2 regressions in rust-lang#96434 (`println` and `eprintln`) and changes all the other similar macros (`write`, `writeln`, `print`, `eprint`) to match the old pre-rust-lang#94868 behavior of `println` and `eprintln`. argument position | before rust-lang#94868 | after rust-lang#94868 | after this PR --- |:---:|:---:|:---: `write!($tmp, "…", …)` | :rage: | :rage: | :smiley_cat: `write!(…, "…", $tmp)` | :rage: | :rage: | :smiley_cat: `writeln!($tmp, "…", …)` | :rage: | :rage: | :smiley_cat: `writeln!(…, "…", $tmp)` | :rage: | :rage: | :smiley_cat: `print!("…", $tmp)` | :rage: | :rage: | :smiley_cat: `println!("…", $tmp)` | :smiley_cat: | :rage: | :smiley_cat: `eprint!("…", $tmp)` | :rage: | :rage: | :smiley_cat: `eprintln!("…", $tmp)` | :smiley_cat: | :rage: | :smiley_cat: `panic!("…", $tmp)` | :smiley_cat: | :smiley_cat: | :smiley_cat: Example of code that is affected by this change: ```rust use std::sync::Mutex; fn main() { let mutex = Mutex::new(0); print!("{}", mutex.lock().unwrap()) /* no semicolon */ } ``` You can see several real-world examples like this in the Crater links at the top of rust-lang#96434. This code failed to compile prior to this PR as follows, but works after this PR. ```console error[E0597]: `mutex` does not live long enough --> src/main.rs:5:18 | 5 | print!("{}", mutex.lock().unwrap()) /* no semicolon */ | ^^^^^^^^^^^^--------- | | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... 6 | } | - | | | `mutex` dropped here while still borrowed | ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `MutexGuard` ```
GuillaumeGomez
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May 14, 2022
Make write/print macros eagerly drop temporaries This PR fixes the 2 regressions in rust-lang#96434 (`println` and `eprintln`) and changes all the other similar macros (`write`, `writeln`, `print`, `eprint`) to match the old pre-rust-lang#94868 behavior of `println` and `eprintln`. argument position | before rust-lang#94868 | after rust-lang#94868 | after this PR --- |:---:|:---:|:---: `write!($tmp, "…", …)` | :rage: | :rage: | :smiley_cat: `write!(…, "…", $tmp)` | :rage: | :rage: | :smiley_cat: `writeln!($tmp, "…", …)` | :rage: | :rage: | :smiley_cat: `writeln!(…, "…", $tmp)` | :rage: | :rage: | :smiley_cat: `print!("…", $tmp)` | :rage: | :rage: | :smiley_cat: `println!("…", $tmp)` | :smiley_cat: | :rage: | :smiley_cat: `eprint!("…", $tmp)` | :rage: | :rage: | :smiley_cat: `eprintln!("…", $tmp)` | :smiley_cat: | :rage: | :smiley_cat: `panic!("…", $tmp)` | :smiley_cat: | :smiley_cat: | :smiley_cat: Example of code that is affected by this change: ```rust use std::sync::Mutex; fn main() { let mutex = Mutex::new(0); print!("{}", mutex.lock().unwrap()) /* no semicolon */ } ``` You can see several real-world examples like this in the Crater links at the top of rust-lang#96434. This code failed to compile prior to this PR as follows, but works after this PR. ```console error[E0597]: `mutex` does not live long enough --> src/main.rs:5:18 | 5 | print!("{}", mutex.lock().unwrap()) /* no semicolon */ | ^^^^^^^^^^^^--------- | | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... 6 | } | - | | | `mutex` dropped here while still borrowed | ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `MutexGuard` ```
MabezDev
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May 17, 2022
…lacrum Make [e]println macros eagerly drop temporaries (for backport) This PR extracts the subset of rust-lang#96455 which is only the parts necessary for fixing the 1.61-beta regressions in rust-lang#96434. My larger PR rust-lang#96455 contains a few other changes relative to the pre-rust-lang#94868 behavior; those are not necessary to backport into 1.61. argument position | before rust-lang#94868 | after rust-lang#94868 | after this PR --- |:---:|:---:|:---: `write!($tmp, "…", …)` | :rage: | :rage: | :rage: `write!(…, "…", $tmp)` | :rage: | :rage: | :rage: `writeln!($tmp, "…", …)` | :rage: | :rage: | :rage: `writeln!(…, "…", $tmp)` | :rage: | :rage: | :rage: `print!("…", $tmp)` | :rage: | :rage: | :rage: `println!("…", $tmp)` | :smiley_cat: | :rage: | :smiley_cat: `eprint!("…", $tmp)` | :rage: | :rage: | :rage: `eprintln!("…", $tmp)` | :smiley_cat: | :rage: | :smiley_cat: `panic!("…", $tmp)` | :smiley_cat: | :smiley_cat: | :smiley_cat:
bors
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May 23, 2022
Make write/print macros eagerly drop temporaries This PR fixes the 2 regressions in rust-lang#96434 (`println` and `eprintln`) and changes all the other similar macros (`write`, `writeln`, `print`, `eprint`) to match the old pre-rust-lang#94868 behavior of `println` and `eprintln`. argument position | before rust-lang#94868 | after rust-lang#94868 | after this PR --- |:---:|:---:|:---: `write!($tmp, "…", …)` | :rage: | :rage: | :smiley_cat: `write!(…, "…", $tmp)` | :rage: | :rage: | :smiley_cat: `writeln!($tmp, "…", …)` | :rage: | :rage: | :smiley_cat: `writeln!(…, "…", $tmp)` | :rage: | :rage: | :smiley_cat: `print!("…", $tmp)` | :rage: | :rage: | :smiley_cat: `println!("…", $tmp)` | :smiley_cat: | :rage: | :smiley_cat: `eprint!("…", $tmp)` | :rage: | :rage: | :smiley_cat: `eprintln!("…", $tmp)` | :smiley_cat: | :rage: | :smiley_cat: `panic!("…", $tmp)` | :smiley_cat: | :smiley_cat: | :smiley_cat: Example of code that is affected by this change: ```rust use std::sync::Mutex; fn main() { let mutex = Mutex::new(0); print!("{}", mutex.lock().unwrap()) /* no semicolon */ } ``` You can see several real-world examples like this in the Crater links at the top of rust-lang#96434. This code failed to compile prior to this PR as follows, but works after this PR. ```console error[E0597]: `mutex` does not live long enough --> src/main.rs:5:18 | 5 | print!("{}", mutex.lock().unwrap()) /* no semicolon */ | ^^^^^^^^^^^^--------- | | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... 6 | } | - | | | `mutex` dropped here while still borrowed | ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `MutexGuard` ```
This was referenced Jul 24, 2022
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#94868 is likely cause (cc @dtolnay)
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