Add regression test for #66756

Author: ecstatic-morse

src/test/ui/consts/control-flow/exhaustive-c-like-enum-match.rs

@@ -0,0 +1,27 @@
+// Test for <https://github.com/rust-lang/rust/issues/66756>
+
+// check-pass
+
+#![feature(const_if_match)]
+
+enum E {
+    A,
+    B,
+    C
+}
+
+const fn f(e: E) {
+    match e {
+        E::A => {}
+        E::B => {}
+        E::C => {}
+    }
+}
+
+const fn g(e: E) {
+    match e {
+        _ => {}
+    }
+}
+
+fn main() {}