Rework casting in raw_hash_set's IsFull().

PiperOrigin-RevId: 636218177
Change-Id: I9f58ccbb468fcc0c44ef12162415f7b721a745bf

absl/container/internal/raw_hash_set.h

@@ -623,7 +623,12 @@ inline h2_t H2(size_t hash) { return hash & 0x7F; }
 
 // Helpers for checking the state of a control byte.
 inline bool IsEmpty(ctrl_t c) { return c == ctrl_t::kEmpty; }
-inline bool IsFull(ctrl_t c) { return c >= static_cast<ctrl_t>(0); }
+inline bool IsFull(ctrl_t c) {
+  // Cast `c` to the underlying type instead of casting `0` to `ctrl_t` as `0`
+  // is not a value in the enum. Both ways are equivalent, but this way makes
+  // linters happier.
+  return static_cast<std::underlying_type_t<ctrl_t>>(c) >= 0;
+}
 inline bool IsDeleted(ctrl_t c) { return c == ctrl_t::kDeleted; }
 inline bool IsEmptyOrDeleted(ctrl_t c) { return c < ctrl_t::kSentinel; }