diff --git a/src/librustc/middle/resolve_lifetime.rs b/src/librustc/middle/resolve_lifetime.rs index 31d250fa08215..a122d84a5aa7e 100644 --- a/src/librustc/middle/resolve_lifetime.rs +++ b/src/librustc/middle/resolve_lifetime.rs @@ -708,15 +708,22 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { match param.kind { GenericParamKind::Lifetime { .. } => { let (name, reg) = Region::early(&self.tcx.hir(), &mut index, ¶m); + let def_id = if let Region::EarlyBound(_ ,def_id , _) = reg { + def_id + } 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.clone(), LifetimeUseSet::Many); elision = Some(reg); } else { lifetimes.insert(name, reg); } } else { + self.lifetime_uses.insert(def_id.clone(), LifetimeUseSet::Many); lifetimes.insert(name, reg); } } @@ -1615,7 +1622,6 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> { _ => None, } { debug!("id = {:?} span = {:?} name = {:?}", id, span, name); - if name.name == kw::UnderscoreLifetime { continue; } diff --git a/src/test/ui/async-await/unused-lifetime.rs b/src/test/ui/async-await/unused-lifetime.rs new file mode 100644 index 0000000000000..1cf546bcb4266 --- /dev/null +++ b/src/test/ui/async-await/unused-lifetime.rs @@ -0,0 +1,42 @@ +// edition:2018 + +// 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. + +#![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); +} + +fn main() {} diff --git a/src/test/ui/async-await/unused-lifetime.stderr b/src/test/ui/async-await/unused-lifetime.stderr new file mode 100644 index 0000000000000..885cdc04cfa4c --- /dev/null +++ b/src/test/ui/async-await/unused-lifetime.stderr @@ -0,0 +1,32 @@ +error: lifetime parameter `'a` never used + --> $DIR/unused-lifetime.rs:26:40 + | +LL | pub async fn func_with_unused_lifetime<'a>(s: &'a str) { + | ^^ + | +note: lint level defined here + --> $DIR/unused-lifetime.rs:7:9 + | +LL | #![deny(unused_lifetimes)] + | ^^^^^^^^^^^^^^^^ + +error: lifetime parameter `'a` never used + --> $DIR/unused-lifetime.rs:31:44 + | +LL | pub async fn func_with_two_unused_lifetime<'a, 'b>(s: &'a str, t: &'b str) { + | ^^ + +error: lifetime parameter `'b` never used + --> $DIR/unused-lifetime.rs:31:48 + | +LL | pub async fn func_with_two_unused_lifetime<'a, 'b>(s: &'a str, t: &'b str) { + | ^^ + +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 +