Add hint for missing lifetime bound on trait object when type alias is used

3 files changed, 105 insertions, 0 deletions

diff --git a/tests/ui/lifetimes/issue-103582-hint-for-missing-lifetime-bound-on-trait-object-using-type-alias.fixed b/tests/ui/lifetimes/issue-103582-hint-for-missing-lifetime-bound-on-trait-object-using-type-alias.fixed
new file mode 100644
index 00000000000..aa3bce2945b
--- /dev/null
+++ b/tests/ui/lifetimes/issue-103582-hint-for-missing-lifetime-bound-on-trait-object-using-type-alias.fixed
@@ -0,0 +1,45 @@
+// run-rustfix
+
+trait Greeter0 {
+    fn greet(&self);
+}
+
+trait Greeter1 {
+    fn greet(&self);
+}
+
+type BoxedGreeter<'a> = (Box<dyn Greeter0 + 'a>, Box<dyn Greeter1 + 'a>);
+//~^ HELP to declare that the trait object captures data from argument `self`, you can add a lifetime parameter `'a` in the type alias
+
+struct FixedGreeter<'a>(pub &'a str);
+
+impl Greeter0 for FixedGreeter<'_> {
+    fn greet(&self) {
+        println!("0 {}", self.0)
+    }
+}
+
+impl Greeter1 for FixedGreeter<'_> {
+    fn greet(&self) {
+        println!("1 {}", self.0)
+    }
+}
+
+struct Greetings(pub Vec<String>);
+
+impl Greetings {
+    pub fn get(&self, i: usize) -> BoxedGreeter {
+        (Box::new(FixedGreeter(&self.0[i])), Box::new(FixedGreeter(&self.0[i])))
+        //~^ ERROR lifetime may not live long enough
+    }
+}
+
+fn main() {
+    let mut g = Greetings {0 : vec!()};
+    g.0.push("a".to_string());
+    g.0.push("b".to_string());
+    g.get(0).0.greet();
+    g.get(0).1.greet();
+    g.get(1).0.greet();
+    g.get(1).1.greet();
+}
diff --git a/tests/ui/lifetimes/issue-103582-hint-for-missing-lifetime-bound-on-trait-object-using-type-alias.rs b/tests/ui/lifetimes/issue-103582-hint-for-missing-lifetime-bound-on-trait-object-using-type-alias.rs
new file mode 100644
index 00000000000..20c88ec6981
--- /dev/null
+++ b/tests/ui/lifetimes/issue-103582-hint-for-missing-lifetime-bound-on-trait-object-using-type-alias.rs
@@ -0,0 +1,45 @@
+// run-rustfix
+
+trait Greeter0 {
+    fn greet(&self);
+}
+
+trait Greeter1 {
+    fn greet(&self);
+}
+
+type BoxedGreeter = (Box<dyn Greeter0>, Box<dyn Greeter1>);
+//~^ HELP to declare that the trait object captures data from argument `self`, you can add a lifetime parameter `'a` in the type alias
+
+struct FixedGreeter<'a>(pub &'a str);
+
+impl Greeter0 for FixedGreeter<'_> {
+    fn greet(&self) {
+        println!("0 {}", self.0)
+    }
+}
+
+impl Greeter1 for FixedGreeter<'_> {
+    fn greet(&self) {
+        println!("1 {}", self.0)
+    }
+}
+
+struct Greetings(pub Vec<String>);
+
+impl Greetings {
+    pub fn get(&self, i: usize) -> BoxedGreeter {
+        (Box::new(FixedGreeter(&self.0[i])), Box::new(FixedGreeter(&self.0[i])))
+        //~^ ERROR lifetime may not live long enough
+    }
+}
+
+fn main() {
+    let mut g = Greetings {0 : vec!()};
+    g.0.push("a".to_string());
+    g.0.push("b".to_string());
+    g.get(0).0.greet();
+    g.get(0).1.greet();
+    g.get(1).0.greet();
+    g.get(1).1.greet();
+}
diff --git a/tests/ui/lifetimes/issue-103582-hint-for-missing-lifetime-bound-on-trait-object-using-type-alias.stderr b/tests/ui/lifetimes/issue-103582-hint-for-missing-lifetime-bound-on-trait-object-using-type-alias.stderr
new file mode 100644
index 00000000000..808d8bb9058
--- /dev/null
+++ b/tests/ui/lifetimes/issue-103582-hint-for-missing-lifetime-bound-on-trait-object-using-type-alias.stderr
@@ -0,0 +1,15 @@
+error: lifetime may not live long enough
+  --> $DIR/issue-103582-hint-for-missing-lifetime-bound-on-trait-object-using-type-alias.rs:32:9
+   |
+LL |     pub fn get(&self, i: usize) -> BoxedGreeter {
+   |                - let's call the lifetime of this reference `'1`
+LL |         (Box::new(FixedGreeter(&self.0[i])), Box::new(FixedGreeter(&self.0[i])))
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ returning this value requires that `'1` must outlive `'static`
+   |
+help: to declare that the trait object captures data from argument `self`, you can add a lifetime parameter `'a` in the type alias
+   |
+LL | type BoxedGreeter<'a> = (Box<dyn Greeter0 + 'a>, Box<dyn Greeter1 + 'a>);
+   |                  ++++                     ++++                    ++++
+
+error: aborting due to previous error
+