From 1caec6fa1d09739f70b1f54766141cf204696503 Mon Sep 17 00:00:00 2001
From: Ethan Brierley <ethanboxx@gmail.com>
Date: Fri, 23 Dec 2022 00:13:47 +0000
Subject: [PATCH] fix: misleading add `dyn` to derive macro suggestion

---
 .../rustc_hir_analysis/src/astconv/mod.rs     |  8 ++++-
 tests/ui/traits/issue-106072.rs               |  5 ++++
 tests/ui/traits/issue-106072.stderr           | 30 +++++++++++++++++++
 3 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 tests/ui/traits/issue-106072.rs
 create mode 100644 tests/ui/traits/issue-106072.stderr

diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 3521911b05527..398dd18f5121d 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -3307,7 +3307,13 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 let label = "add `dyn` keyword before this trait";
                 let mut diag =
                     rustc_errors::struct_span_err!(tcx.sess, self_ty.span, E0782, "{}", msg);
-                diag.multipart_suggestion_verbose(label, sugg, Applicability::MachineApplicable);
+                if self_ty.span.can_be_used_for_suggestions() {
+                    diag.multipart_suggestion_verbose(
+                        label,
+                        sugg,
+                        Applicability::MachineApplicable,
+                    );
+                }
                 // check if the impl trait that we are considering is a impl of a local trait
                 self.maybe_lint_blanket_trait_impl(&self_ty, &mut diag);
                 diag.emit();
diff --git a/tests/ui/traits/issue-106072.rs b/tests/ui/traits/issue-106072.rs
new file mode 100644
index 0000000000000..7064a39d21e7f
--- /dev/null
+++ b/tests/ui/traits/issue-106072.rs
@@ -0,0 +1,5 @@
+#[derive(Clone)] //~  trait objects must include the `dyn` keyword
+                 //~| trait objects must include the `dyn` keyword
+struct Foo;
+trait Foo {} //~ the name `Foo` is defined multiple times
+fn main() {}
diff --git a/tests/ui/traits/issue-106072.stderr b/tests/ui/traits/issue-106072.stderr
new file mode 100644
index 0000000000000..f9b7b814663fd
--- /dev/null
+++ b/tests/ui/traits/issue-106072.stderr
@@ -0,0 +1,30 @@
+error[E0428]: the name `Foo` is defined multiple times
+  --> $DIR/issue-106072.rs:4:1
+   |
+LL | struct Foo;
+   | ----------- previous definition of the type `Foo` here
+LL | trait Foo {}
+   | ^^^^^^^^^ `Foo` redefined here
+   |
+   = note: `Foo` must be defined only once in the type namespace of this module
+
+error[E0782]: trait objects must include the `dyn` keyword
+  --> $DIR/issue-106072.rs:1:10
+   |
+LL | #[derive(Clone)]
+   |          ^^^^^
+   |
+   = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0782]: trait objects must include the `dyn` keyword
+  --> $DIR/issue-106072.rs:1:10
+   |
+LL | #[derive(Clone)]
+   |          ^^^^^
+   |
+   = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0428, E0782.
+For more information about an error, try `rustc --explain E0428`.