Warping not compatible with `--optimize true` and `--via-ir`

[bernard-wagner]

Component

Forge

Have you ensured that all of these are up to date?

• Foundry
• Foundryup

What version of Foundry are you on?

forge Version: 1.2.2-stable
Commit SHA: 73ac79f
Build Timestamp: 2025-06-01T14:56:45.336809000Z (1748789805)
Build Profile: maxperf

What version of Foundryup are you on?

foundryup: 1.0.1

What command(s) is the bug in?

forge test

Operating System

macOS (Apple Silicon)

Describe the bug

When compiling with --via-ir and --optimize true instances of vm.warp() yield unexpected results:

    function test_warping() public {
        uint256 startTime = block.timestamp;

        uint256[8] memory timestamps = [
            uint256(0),
            uint256(86400),
            uint256(604800),
            uint256(2678400),
            uint256(5184000),
            uint256(15811200),
            uint256(31536000),
            uint256(63072000)
        ];

        for (uint256 i = 0; i < timestamps.length; i++) {
            console2.log("Warping to: ", startTime + timestamps[i]);
            vm.warp(startTime + timestamps[i]);
            assertEq(block.timestamp, startTime + timestamps[i], "Warping failed");
        }
    }

When running with forge test -vv --via-ir --optimize false --match-test test_warping it succeeds. The tests fail with forge test -vv --via-ir --optimize true --match-test test_warping:

[FAIL: Warping failed: 86401 != 172801] test_warping() (gas: 10223)
Logs:
  Warping to:  1
  Warping to:  86401

Even when removing the assertEq, startTime + timestamps[i] yields an incorrect result. However, removing vm.warp() as well results in the correct logs. So it's something strange that is happening when using the vm.warp cheatcode.

[bernard-wagner]

It seems that the issue might be more related to startTime = block.timestamp, as setting startTime = 1 seems to work.

[zerosnacks]

Likely related: https://book.getfoundry.sh/reference/cheatcodes/get-block-timestamp#getblocktimestamp