Remove implicit uint256 conversion and comparison
What the developer wrote
Authored by marcofleon
Remove implicit uint256 conversion and comparison
What changed, and why it matters
This commit removes shortcuts that let a new transaction ID type be silently treated as the older uint256 type. It is a code-cleanup change that makes type mismatches produce compile-time errors rather than compile silently. There is no direct evidence this fixes an exploitable vulnerability; it is a hardening/refactoring step.
Treat as a normal code-quality/type-safety improvement. Review downstream call sites that may now fail to compile and must be updated to use explicit `ToUint256()` or `FromUint256()`. No urgent security response is indicated by the commit itself.
Security signals we found
Type-safety hardening: removal of implicit conversion between distinct identifier types
Prevention of silent comparison/conversion between txid, wtxid, and uint256
No runtime behavior change; compile-time enforcement only
TODO comments indicate this was planned refactoring, not an emergency security fix
Evidence from the diff
The commit deletes the implicit operator const uint256&() conversion and the Compare(const uint256&) overload from transaction_identifier<has_witness>. The TODO comments explicitly state these were transitional helpers intended to be removed once most code adopted the new Txid/Wtxid types. Removing them prevents accidental mixing of uint256 and transaction_identifier values, which could previously compile and silently compare or convert between semantically distinct identifiers (e.g., txid vs. wtxid vs. raw uint256).
Changed components
src/util/transaction_identifier.htransaction_identifier<Txid>/transaction_identifier<Wtxid> template classInspect captured patch +0 / −12
diff --git a/src/util/transaction_identifier.h b/src/util/transaction_identifier.h
index 30302f06..b59f2e77 100644
--- a/src/util/transaction_identifier.h
+++ b/src/util/transaction_identifier.h
@@ -24,9 +24,6 @@ class transaction_identifier
// Note: Use FromUint256 externally instead.
transaction_identifier(const uint256& wrapped) : m_wrapped{wrapped} {}
- // TODO: Comparisons with uint256 should be disallowed once we have
- // converted most of the code to using the new txid types.
- constexpr int Compare(const uint256& other) const { return m_wrapped.Compare(other); }
constexpr int Compare(const transaction_identifier<has_witness>& other) const { return m_wrapped.Compare(other.m_wrapped); }
template <typename Other>
constexpr int Compare(const Other& other) const
@@ -65,15 +62,6 @@ public:
constexpr const std::byte* end() const { return reinterpret_cast<const std::byte*>(m_wrapped.end()); }
template <typename Stream> void Serialize(Stream& s) const { m_wrapped.Serialize(s); }
template <typename Stream> void Unserialize(Stream& s) { m_wrapped.Unserialize(s); }
-
- /** Conversion function to `uint256`.
- *
- * Note: new code should use `ToUint256`.
- *
- * TODO: This should be removed once the majority of the code has switched
- * to using the Txid and Wtxid types. Until then it makes for a smoother
- * transition to allow this conversion. */
- operator const uint256&() const LIFETIMEBOUND { return m_wrapped; }
};
/** Txid commits to all transaction fields except the witness. */
Why this scored 18/100
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