fix `unnecessary_semicolon`: don't lint on stmts with attrs (#15466)

fixes https://github.com/rust-lang/rust-clippy/issues/15426

changelog: [`unnecessary_semicolon`]: don't lint on statements with
attributes

4 files changed, 30 insertions, 1 deletions

diff --git a/clippy_lints/src/unnecessary_semicolon.rs b/clippy_lints/src/unnecessary_semicolon.rs
index f1d1a76d0c2..76e24b6bf80 100644
--- a/clippy_lints/src/unnecessary_semicolon.rs
+++ b/clippy_lints/src/unnecessary_semicolon.rs
@@ -86,7 +86,9 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessarySemicolon {
                 expr.kind,
                 ExprKind::If(..) | ExprKind::Match(_, _, MatchSource::Normal | MatchSource::Postfix)
             )
-            && cx.typeck_results().expr_ty(expr) == cx.tcx.types.unit
+            && cx.typeck_results().expr_ty(expr).is_unit()
+            // if a stmt has attrs, then turning it into an expr will break the code, since attrs aren't allowed on exprs
+            && cx.tcx.hir_attrs(stmt.hir_id).is_empty()
         {
             if let Some(block_is_unit) = self.is_last_in_block(stmt) {
                 if cx.tcx.sess.edition() <= Edition2021 && leaks_droppable_temporary_with_limited_lifetime(cx, expr) {
diff --git a/tests/ui/unnecessary_semicolon.edition2021.fixed b/tests/ui/unnecessary_semicolon.edition2021.fixed
index f10d804c8cc..797f1505f49 100644
--- a/tests/ui/unnecessary_semicolon.edition2021.fixed
+++ b/tests/ui/unnecessary_semicolon.edition2021.fixed
@@ -63,3 +63,12 @@ fn issue14100() -> bool {
     // cast into the `bool` function return type.
     if return true {};
 }
+
+fn issue15426(x: u32) {
+    // removing the `;` would turn the stmt into an expr, but attrs aren't allowed on exprs
+    #[rustfmt::skip]
+    match x {
+        0b00 => {}  0b01 => {}
+        0b11 => {}  _    => {}
+    };
+}
diff --git a/tests/ui/unnecessary_semicolon.edition2024.fixed b/tests/ui/unnecessary_semicolon.edition2024.fixed
index 32a3bb9b408..d2609cea000 100644
--- a/tests/ui/unnecessary_semicolon.edition2024.fixed
+++ b/tests/ui/unnecessary_semicolon.edition2024.fixed
@@ -63,3 +63,12 @@ fn issue14100() -> bool {
     // cast into the `bool` function return type.
     if return true {};
 }
+
+fn issue15426(x: u32) {
+    // removing the `;` would turn the stmt into an expr, but attrs aren't allowed on exprs
+    #[rustfmt::skip]
+    match x {
+        0b00 => {}  0b01 => {}
+        0b11 => {}  _    => {}
+    };
+}
diff --git a/tests/ui/unnecessary_semicolon.rs b/tests/ui/unnecessary_semicolon.rs
index 91b28218022..55f1ec84cb0 100644
--- a/tests/ui/unnecessary_semicolon.rs
+++ b/tests/ui/unnecessary_semicolon.rs
@@ -63,3 +63,12 @@ fn issue14100() -> bool {
     // cast into the `bool` function return type.
     if return true {};
 }
+
+fn issue15426(x: u32) {
+    // removing the `;` would turn the stmt into an expr, but attrs aren't allowed on exprs
+    #[rustfmt::skip]
+    match x {
+        0b00 => {}  0b01 => {}
+        0b11 => {}  _    => {}
+    };
+}