# solc-0002 — ContractLevelChecker findDuplicateDefinitions — CLEAN (CWE-407)

## File
`libsolidity/analysis/ContractLevelChecker.cpp` ~line 239

## Pattern reviewed
```cpp
std::set<size_t> reported;
for (size_t i = 0; i < overloads.size() && !reported.count(i); ++i)
```

## CWE-407 verdict: NOT a performance defect

`std::set<size_t>::count` is O(log N), making the loop O(N log N) — well within
acceptable complexity for the use case.  N is bounded by the number of overloaded
definitions of a single name in a contract, which in practice is tiny (< 20).
No CWE-407 patch warranted.

## Separate logic concern (not CWE-407)

The `!reported.count(i)` loop guard has a latent correctness defect: if index `i`
was inserted into `reported` as a *duplicate* during an earlier outer iteration
(e.g., iteration i=0 found j=2 is a duplicate and inserted 2), then when the outer
loop reaches i=2 the guard fires and the loop exits early.  This causes i=2 to be
silently skipped as a *primary* candidate, potentially missing further duplicates
whose first occurrence is at index 2.

This is a correctness/logic defect, not a CWE-407 algorithmic-complexity defect.
It should be tracked separately if it produces missed duplicate-definition errors
in practice.

## Recommendation

Change the loop guard to allow all `i` to be visited as primary candidates:

```cpp
for (size_t i = 0; i < overloads.size(); ++i)
{
    if (reported.count(i)) continue;   // already flagged as someone else's dup
    ...
}
```

This preserves the intent (skip reporting i if it was already reported as a
duplicate of an earlier declaration) while not prematurely terminating the loop.
