Account for macros when suggesting adding lifetime

Fix #70152.

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1645,6 +1645,7 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
         );
         err.span_label(lifetime_ref.span, "undeclared lifetime");
         let mut suggests_in_band = false;
+        let mut suggest_note = true;
         for missing in &self.missing_named_lifetime_spots {
             match missing {
                 MissingLifetimeSpot::Generics(generics) => {
@@ -1664,12 +1665,20 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
                         suggests_in_band = true;
                         (generics.span, format!("<{}>", lifetime_ref))
                     };
-                    err.span_suggestion(
-                        span,
-                        &format!("consider introducing lifetime `{}` here", lifetime_ref),
-                        sugg,
-                        Applicability::MaybeIncorrect,
-                    );
+                    if !span.from_expansion() {
+                        err.span_suggestion(
+                            span,
+                            &format!("consider introducing lifetime `{}` here", lifetime_ref),
+                            sugg,
+                            Applicability::MaybeIncorrect,
+                        );
+                    } else if suggest_note {
+                        suggest_note = false; // Avoid displaying the same help multiple times.
+                        err.help(&format!(
+                            "consider introducing lifetime `{}` to the item's generics",
+                            lifetime_ref,
+                        ));
+                    }
                 }
                 MissingLifetimeSpot::HigherRanked { span, span_type } => {
                     err.span_suggestion(
@@ -1684,7 +1693,7 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
                     );
                     err.note(
                         "for more information on higher-ranked polymorphism, visit \
-                            https://doc.rust-lang.org/nomicon/hrtb.html",
+                         https://doc.rust-lang.org/nomicon/hrtb.html",
                     );
                 }
                 _ => {}
@@ -1696,7 +1705,7 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
         {
             err.help(
                 "if you want to experiment with in-band lifetime bindings, \
-                    add `#![feature(in_band_lifetimes)]` to the crate attributes",
+                 add `#![feature(in_band_lifetimes)]` to the crate attributes",
             );
         }
         err.emit();

src/test/ui/lifetimes/undeclared-lifetime-used-in-debug-macro-issue-70152.rs

@@ -0,0 +1,16 @@
+#[derive(Eq, PartialEq)]
+struct Test {
+    a: &'b str,
+    //~^ ERROR use of undeclared lifetime name `'b`
+    //~| ERROR use of undeclared lifetime name `'b`
+}
+
+trait T {
+    fn foo(&'static self) {}
+}
+
+impl T for Test {
+    fn foo(&'b self) {} //~ ERROR use of undeclared lifetime name `'b`
+}
+
+fn main() {}

src/test/ui/lifetimes/undeclared-lifetime-used-in-debug-macro-issue-70152.stderr

@@ -0,0 +1,38 @@
+error[E0261]: use of undeclared lifetime name `'b`
+  --> $DIR/undeclared-lifetime-used-in-debug-macro-issue-70152.rs:13:13
+   |
+LL |     fn foo(&'b self) {}
+   |             ^^ undeclared lifetime
+   |
+   = help: if you want to experiment with in-band lifetime bindings, add `#![feature(in_band_lifetimes)]` to the crate attributes
+help: consider introducing lifetime `'b` here
+   |
+LL | impl<'b> T for Test {
+   |     ^^^^
+help: consider introducing lifetime `'b` here
+   |
+LL |     fn foo<'b>(&'b self) {}
+   |           ^^^^
+
+error[E0261]: use of undeclared lifetime name `'b`
+  --> $DIR/undeclared-lifetime-used-in-debug-macro-issue-70152.rs:3:9
+   |
+LL | struct Test {
+   |            - help: consider introducing lifetime `'b` here: `<'b>`
+LL |     a: &'b str,
+   |         ^^ undeclared lifetime
+   |
+   = help: if you want to experiment with in-band lifetime bindings, add `#![feature(in_band_lifetimes)]` to the crate attributes
+
+error[E0261]: use of undeclared lifetime name `'b`
+  --> $DIR/undeclared-lifetime-used-in-debug-macro-issue-70152.rs:3:9
+   |
+LL |     a: &'b str,
+   |         ^^ undeclared lifetime
+   |
+   = help: consider introducing lifetime `'b` to the item's generics
+   = help: if you want to experiment with in-band lifetime bindings, add `#![feature(in_band_lifetimes)]` to the crate attributes
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0261`.