`forge coverage` doesn't use via-ir/optimizer setting

[calbera]

When running forge coverage, it builds differently than running forge build (seems like does not use any of the configuration provided in foundry.toml that is used by forge build).

forge coverage fails (due to no via-ir flag set):

>>> forge coverage --report lcov --root ./contracts
[⠒] Compiling...
[⠑] Compiling 112 files with 0.8.21
[⠃] Solc 0.8.21 finished in 2.68s
Error:
Compiler run failed:
Error: Compiler error (/solidity/libsolidity/codegen/LValue.cpp:56):Stack too deep. Try compiling with `--via-ir` (cli) or the equivalent `viaIR: true` (standard JSON) while enabling the optimizer. Otherwise, try removing local variables.

forge build success using via-ir = true from foundry.toml:

>>> forge build --root ./contracts
[⠢] Compiling...
[⠰] Compiling 3 files with 0.8.21
[⠔] Solc 0.8.21 finished in 32.61s
Compiler run successful with warnings:

[calbera]

Ah I see that this is an intentional feature foundry-rs/forge-std#477 (comment). Is there any common work around here?

[mds1]

In order of best results:

1. Refactor your contracts so they don't give stack too deep when compiled with no optimizer and no via-ir
2. Run forge coverage with the --ir-minimum flag

[calbera]

Thanks @mds1! Yeah 1) is the main priority here. However 2) worked as well; should the flag be on the docs page? I didn't see an option on the docs and then never tried forge coverage --help to find the --ir-minimum flag.

[mds1]

Yes it definitely should be in the docs page, if you could open a PR for it that would be awesome! You can learn more about that flag here: #5349