Refine "remove semicolon" suggestion in trait selection

Don't suggest it if the last statement doesn't have a semicolon

Fixes #81098

See also #54771 for why this suggestion was added

2 files changed, 36 insertions, 0 deletions

diff --git a/src/test/ui/suggestions/issue-81098.rs b/src/test/ui/suggestions/issue-81098.rs
new file mode 100644
index 00000000000..a601b5866f4
--- /dev/null
+++ b/src/test/ui/suggestions/issue-81098.rs
@@ -0,0 +1,13 @@
+// Don't suggest removing a semicolon if the last statement isn't an expression with semicolon
+// (#81098)
+fn wat() -> impl core::fmt::Display { //~ ERROR: `()` doesn't implement `std::fmt::Display`
+    fn why() {}
+}
+
+// Do it if the last statement is an expression with semicolon
+// (#54771)
+fn ok() -> impl core::fmt::Display { //~ ERROR: `()` doesn't implement `std::fmt::Display`
+    1;
+}
+
+fn main() {}
diff --git a/src/test/ui/suggestions/issue-81098.stderr b/src/test/ui/suggestions/issue-81098.stderr
new file mode 100644
index 00000000000..2a72159e577
--- /dev/null
+++ b/src/test/ui/suggestions/issue-81098.stderr
@@ -0,0 +1,23 @@
+error[E0277]: `()` doesn't implement `std::fmt::Display`
+  --> $DIR/issue-81098.rs:3:13
+   |
+LL | fn wat() -> impl core::fmt::Display {
+   |             ^^^^^^^^^^^^^^^^^^^^^^^ `()` cannot be formatted with the default formatter
+   |
+   = help: the trait `std::fmt::Display` is not implemented for `()`
+   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
+
+error[E0277]: `()` doesn't implement `std::fmt::Display`
+  --> $DIR/issue-81098.rs:9:12
+   |
+LL | fn ok() -> impl core::fmt::Display {
+   |            ^^^^^^^^^^^^^^^^^^^^^^^ `()` cannot be formatted with the default formatter
+LL |     1;
+   |      - consider removing this semicolon
+   |
+   = help: the trait `std::fmt::Display` is not implemented for `()`
+   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.