[Coverity] Underflow error captured on concurrent_hash_map.h in coverity scan

[ShinYanKokIntel]

Summary

Underflow flagged in the Coverity scan due to variable type. However, it doesn't cause any functional issues or program failures.

Version

Example illustrated using v2021.2.5, but the issue should exists in all versions.

Environment

Environment set-up is not required.

Observed Behavior

The variable s is defined as segment_index_type Link, which is an alias for std::size_t Link, a long unsigned integer type.

The do-while loop executes for any initial value of s, and s reaches 0, underflow occurs. s will wrap around to its maximum representable value, ULONG_MAX.
However, since the loop condition is (s = 0 > 0), which evaluates to false, loop terminates. Therefore, despite the occurrence of underflow, the program's behavior should remain as expected.

Expected Behavior

Suggested modification:

void clear() {
  ...
  do {
    ...
  } while (s > 0 && s-- > 0);
  ...
}

Adding another condition check (s > 0) prior will prevent the execution of s-- when s is 0, but keeping the main loop executing for the case s is 0.

Steps To Reproduce

Compilation not required. Link to line