Gas optimization: Cache BooleanSlot in ReentrancyGuardTransient

[borj404]

Small gas optimization in ReentrancyGuardTransient.sol by pre-computing the BooleanSlot to avoid repeated type conversions.

Current:

REENTRANCY_GUARD_STORAGE.asBoolean().tstore(true);

Proposed:

TransientSlot.BooleanSlot private constant REENTRANCY_SLOT =
    TransientSlot.BooleanSlot.wrap(REENTRANCY_GUARD_STORAGE);

// then use: REENTRANCY_SLOT.tstore(true);

Benefits

• Eliminates redundant .asBoolean() calls (currently called 3 times per nonReentrant execution).
• No functional changes. Same storage slot, same behavior.
• All existing tests pass without modification.
• Testing shows contracts save 1.3K gas at deployment plus 30 gas per nonReentrant modifier execution.

Would maintainers be interested in this micro-optimization? Happy to submit a PR if useful.

[sohamsk13]

Looks good

[borj404]

Update: I have corrected an error in my initial analysis and updated the PR to support the new nonReentrantView modifier.

The accurate breakdown is:

• Runtime savings: 19 gas per nonReentrant execution (reduced from 30 due to the refactored architecture).
• Deployment cost: +1,728 gas (one-time, amortized after ~91 transactions).

While deployment costs more, the optimization pays off quickly for contracts with regular reentrancy guard usage.

Details:

• Full implementation and test results: https://github.com/borj404/openzeppelin-transient-reentrancy-gas-optimization/tree/optimize/reentrancy-guard-transient
• Pull Request: perf: optimize ReentrancyGuardTransient with pre-computed BooleanSlot perf: optimize ReentrancyGuardTransient with pre-computed BooleanSlot #5865