bug(config): do not enable solc optimizer by default

[hbarcelos]

Component

Forge

Describe the feature you would like

The solc optimizer has historically been a source of bugs in smart contracts.

After a couple of years of stability, Solidity 0.8.x's optimizer had some outstanding bugs that could lead to catastrophic problems even when code is correct.

While one can appreciate the gains in gas costs that the optimizer brings, this should be an opt-in instead of the default option, since it can introduce bugs for seemingly correct code. Let's not underestimate the power of defaults.

Additional context

Other tools used in the industry also don't enable the optimizer by default:

• Hardhat

  optimizer: an object with enabled and runs keys. Default value: { enabled: false, runs: 200 }.

• Truffle

  // optimizer: {
  // enabled: false,
  // runs: 200
  // },

• Dapp Tools

  DAPP_BUILD_OPTIMIZE | 0 | -- | -- | --

So anyone coming from them who are not willing to use the optimizer can easily forget to disable it.

[sambacha]

Even defining no optimizations has lead to incorrect settings, leaving it undefined was not the same as explicitly disabling the optimizer

[hbarcelos]

Even defining no optimizations has lead to incorrect settings, leaving it undefined was not the same as explicitly disabling the optimizer

I'm not sure I understood what is your point. Could you please clarify?

[onbjerg]

cc @gakonst this was changed when we introduced config later in that PR, @mattsse thinks this was discussed somewhere but can't find the original discussion, do you remember what the rationale was to enable it by default?

[gakonst]

That was the dapptools default I think. I'm open minded to either, but I personally like the optimizer for most use-cases that do not have to do with low level asm. Could be wrong.

[hbarcelos]

That was the dapptools default I think.

Maybe in earlier versions of dapptools, however the latest docs says otherwise (look for "DAPP_BUILD_OPTIMIZE").

As pointed out in the original comment, most of the widely used tools in the ecosystem DO NOT enable optimizations by default.

[zerosnacks]

Marking this as a bug because it behavior can be perceived as unexpected when coming from other tools. I think it makes sense to make this breaking change pre-1.0. I've had previously assumed it wasn't enabled by default.

[grandizzy]

this would also avoid confusion with coverage not being able to compile while test can without any optimization as in #8840 (comment)

[sambacha]

Even defining no optimizations has lead to incorrect settings, leaving it undefined was not the same as explicitly disabling the optimizer

I'm not sure I understood what is your point. Could you please clarify?

in previous versions of solidity, having your compiler settings not have explicitly mentioned "optimizer" was not the same as having it defined as "optimizer=off" meaning leaving it out of the configuration left it enabled. Some would think leaving it out of the configuration would mean that it was disabled, which was not the case.

the 200 optimizer runs is the solc default which hardhat inherits