2 files changed, 182 insertions, 1 deletions

diff --git a/crates/ide_completion/src/completions/lifetime.rs b/crates/ide_completion/src/completions/lifetime.rs
new file mode 100644
index 000000000..74eb23360
--- /dev/null
+++ b/crates/ide_completion/src/completions/lifetime.rs
@@ -0,0 +1,181 @@
+//! Completes lifetimes.
+use hir::ScopeDef;
+
+use crate::{completions::Completions, context::CompletionContext};
+
+/// Completes lifetimes.
+pub(crate) fn complete_lifetime(acc: &mut Completions, ctx: &CompletionContext) {
+    if !ctx.lifetime_allowed {
+        return;
+    }
+    let param_lifetime = match (
+        &ctx.lifetime_syntax,
+        ctx.lifetime_param_syntax.as_ref().and_then(|lp| lp.lifetime()),
+    ) {
+        (Some(lt), Some(lp)) if lp == lt.clone() => return,
+        (Some(_), Some(lp)) => Some(lp.to_string()),
+        _ => None,
+    };
+
+    ctx.scope.process_all_names(&mut |name, res| {
+        if let ScopeDef::GenericParam(hir::GenericParam::LifetimeParam(_)) = res {
+            if param_lifetime != Some(name.to_string()) {
+                acc.add_resolution(ctx, name.to_string(), &res);
+            }
+        }
+    });
+    if param_lifetime.is_none() {
+        acc.add_static_lifetime(ctx);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::{
+        test_utils::{check_edit, completion_list_with_config, TEST_CONFIG},
+        CompletionConfig, CompletionKind,
+    };
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        check_with_config(TEST_CONFIG, ra_fixture, expect);
+    }
+
+    fn check_with_config(config: CompletionConfig, ra_fixture: &str, expect: Expect) {
+        let actual = completion_list_with_config(config, ra_fixture, CompletionKind::Reference);
+        expect.assert_eq(&actual)
+    }
+
+    #[test]
+    fn check_lifetime_edit() {
+        check_edit(
+            "'lifetime",
+            r#"
+fn func<'lifetime>(foo: &'li$0) {}
+"#,
+            r#"
+fn func<'lifetime>(foo: &'lifetime) {}
+"#,
+        );
+    }
+
+    #[test]
+    fn complete_lifetime_in_ref() {
+        check(
+            r#"
+fn foo<'lifetime>(foo: &'a$0 usize) {}
+"#,
+            expect![[r#"
+                lt 'lifetime
+                lt 'static
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_lifetime_in_ref_missing_ty() {
+        check(
+            r#"
+fn foo<'lifetime>(foo: &'a$0) {}
+"#,
+            expect![[r#"
+                lt 'lifetime
+                lt 'static
+            "#]],
+        );
+    }
+    #[test]
+    fn complete_lifetime_in_self_ref() {
+        check(
+            r#"
+struct Foo;
+impl<'impl> Foo {
+    fn foo<'func>(&'a$0 self) {}
+}
+"#,
+            expect![[r#"
+                lt 'func
+                lt 'impl
+                lt 'static
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_lifetime_in_arg_list() {
+        check(
+            r#"
+struct Foo<'lt>;
+fn foo<'lifetime>(_: Foo<'a$0>) {}
+"#,
+            expect![[r#"
+                lt 'lifetime
+                lt 'static
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_lifetime_in_where_pred() {
+        check(
+            r#"
+fn foo2<'lifetime, T>() where 'a$0 {}
+"#,
+            expect![[r#"
+                lt 'lifetime
+                lt 'static
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_lifetime_in_ty_bound() {
+        check(
+            r#"
+fn foo2<'lifetime, T>() where T: 'a$0 {}
+"#,
+            expect![[r#"
+                lt 'lifetime
+                lt 'static
+            "#]],
+        );
+        check(
+            r#"
+fn foo2<'lifetime, T>() where T: Trait<'a$0> {}
+"#,
+            expect![[r#"
+                lt 'lifetime
+                lt 'static
+            "#]],
+        );
+    }
+
+    #[test]
+    fn dont_complete_lifetime_in_assoc_ty_bound() {
+        check(
+            r#"
+fn foo2<'lifetime, T>() where T: Trait<Item = 'a$0> {}
+"#,
+            expect![[r#""#]],
+        );
+    }
+
+    #[test]
+    fn complete_lifetime_in_param_list() {
+        check(
+            r#"
+fn foo<'a$0>() {}
+"#,
+            expect![[r#""#]],
+        );
+        check(
+            r#"
+fn foo<'footime, 'lifetime: 'a$0>() {}
+"#,
+            expect![[r#"
+                lt 'footime
+            "#]],
+        );
+    }
+}
diff --git a/crates/ide_completion/src/completions/pattern.rs b/crates/ide_completion/src/completions/pattern.rs
index 476eecff0..b06498e6d 100644
--- a/crates/ide_completion/src/completions/pattern.rs
+++ b/crates/ide_completion/src/completions/pattern.rs
@@ -1,4 +1,4 @@
-//! Completes constats and paths in patterns.
+//! Completes constants and paths in patterns.
 
 use crate::{CompletionContext, Completions};