bug: `vm.txGasPrice` cheatcode incompatible with `--gas-report/--isolate` option

[KirienzoEth]

Component

Forge

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

• Foundry
• Foundryup

What version of Foundry are you on?

forge 0.2.0 (2f432fb 2024-02-29T00:16:38.827810253Z)

What command(s) is the bug in?

forge test --gas-report

Operating System

Windows

Describe the bug

Example repo: https://github.com/KirienzoEth/foundry-gas-report-txgasprice-issue

The vm.txGasPrice cheatcode seems to be incompatible with the use of --gas-report in functions that use tx.gasprice.

The --gas-report option seem to be calling the contract that is tested with a new transaction (to measure the gas used I'm assuming), but as vm.txGasPrice only works in the current transaction (see foundry book), any function relying on tx.gasprice will fail.

[klkvr]

It's happening because of this line:

foundry/crates/evm/evm/src/inspectors/stack.rs

Line 597 in f3be628

ecx.env.tx.gas_price = U256::ZERO;

When removing it and running tests with --isolate as default, there is a falining test can_deploy_with_create2. It's failing because for scripts we are simply changing caller of CREATE2 deployment to DEFAULT_CREATE2_DEPLOYER if it should be broadcasted. That way, because of non-zero gas price in forking environment, revm expects create2 deployer to have enough funds to pay gas * gas_price

So we can either prefund create2 deployer along with caller when initializing test/script runner, or prefund it at apply_create2_deployer (https://github.com/foundry-rs/foundry/blob/master/crates/cheatcodes/src/inspector.rs#L1432) when it's actually being used

It is also worth noting that removing gas price overwriting might break some tests

Right now it is possible to do something like this:

vm.txGasPrice(1); // basically anything non-zero
vm.startPrank(ALICE); // prank address with zero balance
someContract.someMethod();

call to someContract will revert in isolation because revm expects ALICE to have enough funds to pay for gas

cc @mattsse @onbjerg

[grandizzy]

confirming still reproducible with latest version