Auto merge of #72756 - RalfJung:rollup-tbjmtx2, r=RalfJung

Rollup of 9 pull requests

Successful merges:

 - #67460 (Tweak impl signature mismatch errors involving `RegionKind::ReVar` lifetimes)
 - #71095 (impl From<[T; N]> for Box<[T]>)
 - #71500 (Make pointer offset methods/intrinsics const)
 - #71804 (linker: Support `-static-pie` and `-static -shared`)
 - #71862 (Implement RFC 2585: unsafe blocks in unsafe fn)
 - #72103 (borrowck `DefId` -> `LocalDefId`)
 - #72407 (Various minor improvements to Ipv6Addr::Display)
 - #72413 (impl Step for char (make Range*<char> iterable))
 - #72439 (NVPTX support for new asm!)

Failed merges:

r? @ghost

1 files changed, 12 insertions, 3 deletions

diff --git a/src/librustc_errors/diagnostic.rs b/src/librustc_errors/diagnostic.rs
index 1cc5daafed1..cff83c3d5cd 100644
--- a/src/librustc_errors/diagnostic.rs
+++ b/src/librustc_errors/diagnostic.rs
@@ -193,9 +193,18 @@ impl Diagnostic {
         expected_extra: &dyn fmt::Display,
         found_extra: &dyn fmt::Display,
     ) -> &mut Self {
-        let expected_label = format!("expected {}", expected_label);
-
-        let found_label = format!("found {}", found_label);
+        let expected_label = expected_label.to_string();
+        let expected_label = if expected_label.is_empty() {
+            "expected".to_string()
+        } else {
+            format!("expected {}", expected_label)
+        };
+        let found_label = found_label.to_string();
+        let found_label = if found_label.is_empty() {
+            "found".to_string()
+        } else {
+            format!("found {}", found_label)
+        };
         let (found_padding, expected_padding) = if expected_label.len() > found_label.len() {
             (expected_label.len() - found_label.len(), 0)
         } else {