fix block with no termination in or patterns

crates/hir-ty/src/mir/lower.rs

@@ -1039,7 +1039,11 @@ impl MirLowerCtx<'_> {
                         }
                     }
                 }
-                (then_target, (!finished).then_some(current))
+                if !finished {
+                    let ce = *current_else.get_or_insert_with(|| self.new_basic_block());
+                    self.set_goto(current, ce);
+                }
+                (then_target, current_else)
             }
             Pat::Record { .. } => not_supported!("record pattern"),
             Pat::Range { .. } => not_supported!("range pattern"),

crates/ide-diagnostics/src/handlers/mutability_errors.rs

@@ -574,6 +574,27 @@ fn main() {
         );
     }
 
+    #[test]
+    fn or_pattern_no_terminator() {
+        check_diagnostics(
+            r#"
+enum Foo {
+    A, B, C, D
+}
+
+use Foo::*;
+
+fn f(inp: (Foo, Foo, Foo, Foo)) {
+    let ((A, B, _, x) | (B, C | D, x, _)) = inp else {
+        return;
+    };
+    x = B;
+  //^^^^^ 💡 error: cannot mutate immutable variable `x`
+}
+"#,
+        );
+    }
+
     #[test]
     fn respect_allow_unused_mut() {
         // FIXME: respect