Leave promoteds untainted by errors when borrowck fails#111038
Leave promoteds untainted by errors when borrowck fails#111038bors merged 1 commit intorust-lang:masterfrom
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Previously, when borrowck failed it would taint all promoteds within the MIR body. An attempt to evaluated the promoteds would subsequently fail with spurious "note: erroneous constant used". For example: ```console ... note: erroneous constant used --> tests/ui/borrowck/tainted-promoteds.rs:7:9 | 7 | a = &0 * &1 * &2 * &3; | ^^ note: erroneous constant used --> tests/ui/borrowck/tainted-promoteds.rs:7:14 | 7 | a = &0 * &1 * &2 * &3; | ^^ note: erroneous constant used --> tests/ui/borrowck/tainted-promoteds.rs:7:19 | 7 | a = &0 * &1 * &2 * &3; | ^^ note: erroneous constant used --> tests/ui/borrowck/tainted-promoteds.rs:7:24 | 7 | a = &0 * &1 * &2 * &3; | ^^ ``` Borrowck failure doesn't indicate that there is anything wrong with promoteds. Leave them untainted.
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r? @lcnr (rustbot has picked a reviewer for you, use r? to override) |
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Some changes occurred to MIR optimizations cc @rust-lang/wg-mir-opt |
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Yeah, I have no idea why I made the I don't really think there are ways of triggering a (meaningful) borrowck error on a promoted constant anyways, though happy to be disproven by an example... I checked, it also gets rid of the "erroneous constant" note at the end of: fn main() {
println!("{}", {
let x: &str;
x
});
}error[E0381]: used binding `x` isn't initialized
--> /home/gh-compiler-errors/test.rs:4:9
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3 | let x: &str;
| - binding declared here but left uninitialized
4 | x
| ^ `x` used here but it isn't initialized
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help: consider assigning a value
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3 | let x: &str = todo!();
| +++++++++
note: erroneous constant used
--> /home/gh-compiler-errors/test.rs:2:14
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2 | println!("{}", {
| ^^^^r=me when green |
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There's the error in #71587, not sure if that counts as "meaningful" or not. |
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@matthewjasper: Sorry, by "meaningful", I guess I should've been more clear. What I mean is borrowck errors that are likely to cause spurious const-eval errors or ICEs. It doesn't seem like that's the case with the class of issues you fixed in #71587, though, and it doesn't seem like any other existing UI tests were affected by this change, so I consider this PR to be pretty low-risk. The only possible issue is that we might see are spurious const eval errors or ICEs from no longer tainting these promoteds, thus leading to them being evaluated... @bors r+ |
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…iaskrgr Rollup of 7 pull requests Successful merges: - rust-lang#109540 (std docs: edit `PathBuf::set_file_name` example) - rust-lang#110093 (Add 64-bit `time_t` support on 32-bit glibc Linux to `set_times`) - rust-lang#110987 (update wasi_clock_time_api ref.) - rust-lang#111038 (Leave promoteds untainted by errors when borrowck fails) - rust-lang#111042 (Add `#[no_coverage]` to the test harness's `fn main`) - rust-lang#111057 (Make sure the implementation of TcpStream::as_raw_fd is fully inlined) - rust-lang#111065 (Explicitly document how Send and Sync relate to references) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
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Previously, when borrowck failed it would taint all promoteds within the MIR body. An attempt to evaluated the promoteds would subsequently fail with spurious "note: erroneous constant used". For example:
Borrowck failure doesn't indicate that there is anything wrong with promoteds. Leave them untainted.
Fixes #110856.