File import callback not supported error in Foundry

Question

I'm writing smart contract using Foundry. When I try to import contract from github like this:

import "@openzeppelin/contracts/token/ERC20/IERC20";

I will see error like this:

Source "@openzeppelin/contracts/token/ERC20/IERC20" not found: File import callback not supported

I think I have done the necessary things in which I have added the package like this:

forge install Openzeppelin/openzeppelin-contracts

and written remappings in foundry.toml file.

remappings = ["@openzeppelin/=lib/openzeppelin-contracts/contracts"]

But i still see the error. How can I fix the error?

Answer 1

Try changing taking out the second. “Contracts” on the right side of the remapping

If you are using VS Code, add this to .vscode in your project root like :

{ "solidity.packageDefaultDependenciesContractsDirectory": "src", 
"solidity.packageDefaultDependenciesDirectory": "lib",
 "solidity.compileUsingRemoteVersion": "v0.8.15", 
"solidity.remappings": [ "forge-std/=lib/forge-std/src/", 
                     "@openzeppelin/=lib/openzeppelin-contracts/",] 
} 

Answer 2

The remapping has to be in a remapping.txt file, not in the foundry.toml

After after adding

@openzeppelin/=lib/openzeppelin-contracts/

to this remamping.txt the error should be gone.

---

see: https://book.getfoundry.sh/projects/dependencies

"You can customize these remappings by creating a remappings.txt file in the root of your project."