Slow compilation with via-ir

[zeroknots]

Currently trying to integrate Uniswap's universal router. https://github.com/Uniswap/universal-router

Working with this code requires via-ir. Unfortunately I am experiencing extremely slow compile times:

reproduce:

git clone [email protected]:Uniswap/universal-router.git
cd universal-router
forge install
forge build
...
[⠰] Compiling 83 files with 0.8.17
[⠑] Solc 0.8.17 finished in **78.06s** <-- makes me sad

Compiling with hardhat:
pnpm compile --force 19.11s user 0.45s system 105% cpu 18.468 total

Versions:
forge 0.2.0 (28b2ae6 2023-03-06T00:04:30.253422Z)
solc 0.8.17

I assume this might be related to #225

[PaulRBerg]

There's nothing wrong with Forge Std. You just need a set-up that uses via IR only for the contracts in src, and uses non-IR for tests. References:

• https://twitter.com/PaulRBerg/status/1610229563128152064
• Understanding the use of precompiled contracts in tests ProjectOpenSea/seaport#808

Here's an example Foundry config:

[profile.default]
  fs_permissions = [{ access = "read", path = "./optimized-out" }]
  libs = ["lib"]
  optimizer = true
  optimizer_runs = 5_000
  out = "out"
  script = "script"
  solc = "0.8.19"
  src = "src"
  test = "test"

# Compile only the production code with IR
[profile.optimized]
  out = "optimized-out"
  test = "src"
  via_ir = true

[mds1]

This reproduction case doesn't demonstrate that forge-std is the issue here. It seems to me that forge build is a lot slower because it's compiling many solidity source AND solidity test files with via-ir (which you can workaround using the apporach @PaulRBerg mentioned), whereas hardhat is only compiling source files.

Looking at the recent successful CI runs in this repo, the via-ir builds of forge-std still only take 5 seconds (at the time of #225 it was 30-90 seconds)