Closed
Description
This code is a subset of the sqlx crate code that is no longer compiling on the nightly (nightly change was very recent, it was working fine a few versions ago). Matching bug in sqlx crate - launchbadge/sqlx#2855
trait Database: for<'r> HasValueRef<'r, Database = Self> {}
trait HasValueRef<'r> {
type Database: Database;
}
struct Any;
impl Database for Any {}
impl<'r> HasValueRef<'r> for Any {
type Database = Any;
}I expected to see this happen: code compiles
Instead, this happened: code fails to compile using +nightly
Meta
Version that compiles fine: rustc --version:
rustc 1.73.0
Version that fails to compile: rustc +nightly --version --verbose
rustc 1.75.0-nightly (4b85902b4 2023-11-04)
binary: rustc
commit-hash: 4b85902b438f791c5bfcb6b1c5b476d5b88e2bef
commit-date: 2023-11-04
host: x86_64-unknown-linux-gnu
release: 1.75.0-nightly
LLVM version: 17.0.4
`cargo +nightly build` results
✦ ❯ cargo +nightly build
Compiling mydemo v0.1.0 (...)
error[E0308]: mismatched types
--> src/bin/main.rs:12:21
|
12 | type Database = Any;
| ^^^ lifetime mismatch
|
= note: expected associated type `<Any as HasValueRef<'r>>::Database`
found associated type `<Any as HasValueRef<'r>>::Database`
note: the required lifetime does not necessarily outlive the lifetime `'r` as defined here
--> src/bin/main.rs:11:6
|
11 | impl<'r> HasValueRef<'r> for Any {
| ^^
note: the lifetime requirement is introduced here
--> src/bin/main.rs:4:20
|
4 | type Database: Database;
| ^^^^^^^^
error[E0308]: mismatched types
--> src/bin/main.rs:12:21
|
12 | type Database = Any;
| ^^^ lifetime mismatch
|
= note: expected associated type `<Any as HasValueRef<'r>>::Database`
found associated type `<Any as HasValueRef<'r>>::Database`
note: the lifetime `'r` as defined here doesn't meet the lifetime requirements
--> src/bin/main.rs:11:6
|
11 | impl<'r> HasValueRef<'r> for Any {
| ^^
note: the lifetime requirement is introduced here
--> src/bin/main.rs:4:20
|
4 | type Database: Database;
| ^^^^^^^^