diff options
| -rw-r--r-- | compiler/rustc_resolve/src/late/lifetimes.rs | 20 | ||||
| -rw-r--r-- | src/test/ui/async-await/unused-lifetime.rs | 79 | ||||
| -rw-r--r-- | src/test/ui/async-await/unused-lifetime.stderr | 30 |
3 files changed, 65 insertions, 64 deletions
diff --git a/compiler/rustc_resolve/src/late/lifetimes.rs b/compiler/rustc_resolve/src/late/lifetimes.rs index cc0e99dc6b1..aab5c3cf8f5 100644 --- a/compiler/rustc_resolve/src/late/lifetimes.rs +++ b/compiler/rustc_resolve/src/late/lifetimes.rs @@ -644,17 +644,17 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { } else { bug!(); }; - if let hir::ParamName::Plain(param_name) = name { - if param_name.name == kw::UnderscoreLifetime { - // Pick the elided lifetime "definition" if one exists - // and use it to make an elision scope. - self.lifetime_uses.insert(def_id, LifetimeUseSet::Many); - elision = Some(reg); - } else { - lifetimes.insert(name, reg); - } + // We cannot predict what lifetimes are unused in opaque type. + self.lifetime_uses.insert(def_id, LifetimeUseSet::Many); + if let hir::ParamName::Plain(Ident { + name: kw::UnderscoreLifetime, + .. + }) = name + { + // Pick the elided lifetime "definition" if one exists + // and use it to make an elision scope. + elision = Some(reg); } else { - self.lifetime_uses.insert(def_id, LifetimeUseSet::Many); lifetimes.insert(name, reg); } } diff --git a/src/test/ui/async-await/unused-lifetime.rs b/src/test/ui/async-await/unused-lifetime.rs index 1cf546bcb42..5bd6ae8d3a4 100644 --- a/src/test/ui/async-await/unused-lifetime.rs +++ b/src/test/ui/async-await/unused-lifetime.rs @@ -1,42 +1,47 @@ -// edition:2018 +// Check "unused_lifetimes" lint on both async and sync functions -// Avoid spurious warnings of unused lifetime. The below async functions -// are desugered to have an unused lifetime -// but we don't want to warn about that as there's nothing they can do about it. +// edition:2018 #![deny(unused_lifetimes)] -#![allow(dead_code)] - -pub async fn october(s: &str) { - println!("{}", s); -} - -pub async fn async_fn(&mut ref s: &mut[i32]) { - println!("{:?}", s); -} - -macro_rules! foo_macro { - () => { - pub async fn async_fn_in_macro(&mut ref _s: &mut[i32]) {} - }; -} - -foo_macro!(); - -pub async fn func_with_unused_lifetime<'a>(s: &'a str) { - //~^ ERROR lifetime parameter `'a` never used - println!("{}", s); -} - -pub async fn func_with_two_unused_lifetime<'a, 'b>(s: &'a str, t: &'b str) { - //~^ ERROR lifetime parameter `'a` never used - //~^^ ERROR lifetime parameter `'b` never used - println!("{}", s); -} - -pub async fn func_with_unused_lifetime_in_two_params<'c>(s: &'c str, t: &'c str) { - //~^ ERROR lifetime parameter `'c` never used - println!("{}", s); -} + + +// Async part with unused lifetimes +// +// Even wrong cases don't cause errors because async functions are desugared with all lifetimes +// involved in the signature. So, we cannot predict what lifetimes are unused in async function. +async fn async_wrong_without_args<'a>() {} + +async fn async_wrong_1_lifetime<'a>(_: &i32) {} + +async fn async_wrong_2_lifetimes<'a, 'b>(_: &'a i32, _: &i32) {} + +async fn async_right_1_lifetime<'a>(_: &'a i32) {} + +async fn async_right_2_lifetimes<'a, 'b>(_: &'a i32, _: &'b i32) {} + +async fn async_right_trait_bound_lifetime<'a, I>(_: I) +where + I: Iterator<Item = &'a i32> +{} + + +// Sync part with unused lifetimes +// +// These functions are compiled as supposed +fn wrong_without_args<'a>() {} //~ ERROR lifetime parameter `'a` never used + +fn wrong_1_lifetime<'a>(_: &i32) {} //~ ERROR lifetime parameter `'a` never used + +fn wrong_2_lifetimes<'a, 'b>(_: &'a i32, _: &i32) {} //~ ERROR lifetime parameter `'b` never used + +fn right_1_lifetime<'a>(_: &'a i32) {} + +fn right_2_lifetimes<'a, 'b>(_: &'a i32, _: &'b i32) {} + +fn right_trait_bound_lifetime<'a, I>(_: I) +where + I: Iterator<Item = &'a i32> +{} + fn main() {} diff --git a/src/test/ui/async-await/unused-lifetime.stderr b/src/test/ui/async-await/unused-lifetime.stderr index 2a7a12a3643..4e90f43fdd0 100644 --- a/src/test/ui/async-await/unused-lifetime.stderr +++ b/src/test/ui/async-await/unused-lifetime.stderr @@ -1,32 +1,28 @@ error: lifetime parameter `'a` never used - --> $DIR/unused-lifetime.rs:26:40 + --> $DIR/unused-lifetime.rs:31:23 | -LL | pub async fn func_with_unused_lifetime<'a>(s: &'a str) { - | ^^ +LL | fn wrong_without_args<'a>() {} + | -^^- help: elide the unused lifetime | note: the lint level is defined here - --> $DIR/unused-lifetime.rs:7:9 + --> $DIR/unused-lifetime.rs:5:9 | LL | #![deny(unused_lifetimes)] | ^^^^^^^^^^^^^^^^ error: lifetime parameter `'a` never used - --> $DIR/unused-lifetime.rs:31:44 + --> $DIR/unused-lifetime.rs:33:21 | -LL | pub async fn func_with_two_unused_lifetime<'a, 'b>(s: &'a str, t: &'b str) { - | ^^ +LL | fn wrong_1_lifetime<'a>(_: &i32) {} + | -^^- help: elide the unused lifetime error: lifetime parameter `'b` never used - --> $DIR/unused-lifetime.rs:31:48 + --> $DIR/unused-lifetime.rs:35:26 | -LL | pub async fn func_with_two_unused_lifetime<'a, 'b>(s: &'a str, t: &'b str) { - | ^^ +LL | fn wrong_2_lifetimes<'a, 'b>(_: &'a i32, _: &i32) {} + | --^^ + | | + | help: elide the unused lifetime -error: lifetime parameter `'c` never used - --> $DIR/unused-lifetime.rs:37:54 - | -LL | pub async fn func_with_unused_lifetime_in_two_params<'c>(s: &'c str, t: &'c str) { - | ^^ - -error: aborting due to 4 previous errors +error: aborting due to 3 previous errors |