Turn on ABIEncoderV2 by default

[axic]

Question: should there be a pragma for enabling ABIEncoderV1?

Should track here what is needed to achieve this: TBA

[axic]

I could see us enabling V2 in 0.8.0 but keeping V1 for another major release and only dropping it in 0.9.0.

[ekpyron]

Hopefully, we'll have proper fuzzing against the Isabelle implementation soon. It'd be much safer to only default to it, once we can properly fuzz it.

[chriseth]

I'm actually not too worried about correctness, I'm more worried about increased gas costs.

[chriseth]

We could have a pragma to set the abi coder to v1, and enable v2 by default.

[axic]

Could have a pragma like pragma ABICoder V1 and pragma ABICoder V2 and we default to V2 if not set?

[chriseth]

Discussion:

• pragma abicoder v1
• pragma abicoder v2 (default from 0.8)
• pragma experimental ABIEncoderV2 generates warning.

Support in 0.7.x already:

• pragma abicoder v1
• pragma abicoder v2

[axic]

I really wish we could remove the pragma experimental ABIEncoderV2, and not wait until 0.9.0 to do so 😉

[chriseth]

I'll wait with this until some more tests are extracted.

[chriseth]

Implemented in #10336