multiple spurious errors when T: 'static is required in async fn

Given this code:

async fn test<T>(_: &u8) {
    let _: &'static T;
    //~^ ERROR the parameter type `T` may not live long enough
    //~| ERROR the parameter type `T` may not live long enough
}

Two errors are emitted: one requires T: 'static, as expected, and the other requires T: 'a where 'a is the anonymous lifetime.

This affects lifetime constraints that originate in async fn, async blocks, and closures.

An error is emitted for each lifetime that appears in the function because 'static is an upper bound for all lifetimes.

error[E0310]: the parameter type `T` may not live long enough
 --> src/lib.rs:2:12
  |
2 |     let _: &'static T;
  |            ^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
  |
help: consider adding an explicit lifetime bound...
  |
1 | async fn test<T: 'static>(_: &u8) {
  |                +++++++++

error[E0311]: the parameter type `T` may not live long enough
 --> src/lib.rs:2:12
  |
2 |     let _: &'static T;
  |            ^^^^^^^^^^
  |
note: the parameter type `T` must be valid for the anonymous lifetime defined here...
 --> src/lib.rs:1:21
  |
1 | async fn test<T>(_: &u8) {
  |                     ^^^
note: ...so that the type `T` will meet its required lifetime bounds
 --> src/lib.rs:2:12
  |
2 |     let _: &'static T;
  |            ^^^^^^^^^^
help: consider adding an explicit lifetime bound...
  |
1 | async fn test<'a, T: 'a>(_: &'a u8) {
  |               +++  ++++      ++

Triage: To avoid any misunderstanding, would you mind elaborating on what output you expect to see, and not only what you actually see? Thanks!

Here is the current output:

$ rustc +nightly-2026-03-01 --crate-type lib /home/martin/src/lib.rs --edition 2021
error[E0310]: the parameter type `T` may not live long enough
 --> /home/martin/src/lib.rs:2:12
  |
2 |     let _: &'static T;
  |            ^^^^^^^^^^
  |            |
  |            the parameter type `T` must be valid for the static lifetime...
  |            ...so that the type `T` will meet its required lifetime bounds
  |
help: consider adding an explicit lifetime bound
  |
1 | async fn test<T: 'static>(_: &u8) {
  |                +++++++++

error[E0311]: the parameter type `T` may not live long enough
 --> /home/martin/src/lib.rs:2:12
  |
1 | async fn test<T>(_: &u8) {
  |                     --- the parameter type `T` must be valid for the anonymous lifetime defined here...
2 |     let _: &'static T;
  |            ^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
  |
help: consider adding an explicit lifetime bound
  |
1 | async fn test<'a, T: 'a>(_: &'a u8) {
  |               +++  ++++      ++

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0310, E0311.
For more information about an error, try `rustc --explain E0310`.

Rollup merge of rust-lang#158153 - pbkx:issue-115376-async-spurious-s…

Unrolled build for #158153 in rollup 162434

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multiple spurious errors when `T: 'static` is required in async fn #115376

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multiple spurious errors when T: 'static is required in async fn #115376

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Enselic commented on Mar 25, 2026

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multiple spurious errors when `T: 'static` is required in async fn #115376