contracts/ISwapRouter.sol:11:26: TypeError: Interfaces cannot inherit

Question

So I am using some uniswapv3 contracts (which are pragma 0.7+) within another contract (which is pragma 0.5.0) and when compiling I have this error : ```These files import other files that use a different and incompatible version of Solidity:

• contracts/Flashloan.sol (^0.5.0) imports contracts/ISwapRouter.sol (>=0.7.5) and contracts/IQuoter.sol (>=0.7.5)```

so I tried to change the pragma statement from uniswapV3 interfaces I am importing from 0.7.6 to 0.5.0 and I faced this error : contracts/ISwapRouter.sol:11:26: TypeError: Interfaces cannot inherit..

The main question is : How do you handle compiling a contract using solidity v0.5.0 while you use contract that are declared as 0.7+ ?

Answer 1

I wondered how could Uniswap compile its contract if Interfaces can't inherit from other Interfaces ? And I concluded that interfaces imports were added in later solidity versions.

The way I solved this problem was by changing interfaces pragma statement to match the main contract and instead of importing the interfaces and inheriting from it, I directly added them into the code.

This might not be the best way to fix this, but it worked. I am putting it out there as I didn't find an answer to this problem and had to figure it out myself.

If you have a better way to compile contracts which inherit/use contracts with other solidity versions than their own, please feel free to share, I would love to learn.