feat(forge-lint): [claude] check for unwrapped modifiers

[0xClandestine]

Motivation

Coauthored by Claude 4 Opus Max

Modifiers in Solidity that contain logic directly in their body can lead to code duplication when used across multiple functions. Since modifiers are inlined at compile time, any logic within them is duplicated for each function that uses the modifier increasing contract size and deployment cost. A common best practice is to extract modifier logic into internal functions that can be called from within the modifier, reducing code duplication and contract size.

Solution

This PR adds a new gas optimization lint unwrapped-modifier-logic that detects when modifiers contain logic directly in their body instead of using internal/private/public/library functions.

The lint checks for modifiers that contain any statements other than:

• Direct calls to internal/private/public/library functions.
• The placeholder _;

Example of code that triggers the lint:

modifier onlyOwner() {
    require(msg.sender == owner, "Not owner"); // Unwrapped logic
    _;
}

Recommended pattern:

modifier onlyOwner() {
    _checkOwner(); // Wrapped in internal function
    _;
}

function _checkOwner() internal view {
    require(msg.sender == owner, "Not owner");
}

PR Checklist

• Added Tests - Created testdata/ModifierLogic.sol and testdata/ModifierLogic.stderr with comprehensive test cases
• Added Documentation - Need to add lint documentation to the Foundry book under the gas optimization section
• Breaking changes - No breaking changes, this is a new lint rule

[grandizzy]

thank you, makes sense. left some nits, pending @0xrusowsky @DaniPopes review

[0xrusowsky]

overall the PR looks good, however i'd like to hold it back until we merge:

• feat(forge-lint): new LateLintPass + support code snippets #10846

and then make it do a fix suggestion

[kaxhnet]

\

[grandizzy]

overall the PR looks good, however i'd like to hold it back until we merge:

* [feat(forge-lint): new `LateLintPass` + support code snippets #10846](https://github.com/foundry-rs/foundry/pull/10846)

and then make it do a fix suggestion

that's merged now so we can rebuild this PR on top of it

[0xrusowsky]

@0xClandestine if u want to see an example of how to generate snippets, you can check:

• https://github.com/foundry-rs/foundry/blob/rusowsky/keccak-gen-asm/crates/lint/src/sol/gas/keccak.rs

note that in that case, rather than using the AST, i used the HIR cause i needed semantic info (i think that for you case the AST should be enough)

[0xrusowsky]

please improve the code suggestions, and let's wait for others to voice their opinions on whether to use fn post_source_unit or not

[0xClandestine]

i've made the changes that i originally i made on: rusowsky/trim-rmv-span which improves the devex and will close:

• feat(lint): auto remove indentation of code to be removed when using ctx.emit_with_fix() #11038

i also pushed a follow-up commit to integrate the changes and add some minor simplifications

@0xClandestine please lmk if u'll take the migration to using the HIR otherwise i'll do it myself later on this week. The PR is almost there, we just need to polish these final details!

Yo sorry for the delay thought we were waiting on #11038, I'll give it a shot this evening. If I have issues feel free to get this across the finish line. Thanks for staying on top of this 🤝

[0xrusowsky]

overall looks good! please add tests for contract calls, and tomorrow i'll do some final cleanup 🙂

[0xrusowsky]

note for other reviewers:

i merged the changes that i originally i made on: https://github.com/foundry-rs/foundry/tree/rusowsky/trim-rmv-span which improves the devex and will close

• #11038

i did it here cause it was easier to iterate and make sure that the indentation logic was correct (using the snippets of this new lint)

[0xrusowsky]

@0xClandestine even if there is some extra feedback from others, i think you can already start your PR to the https://github.com/foundry-rs/book (the CI won't pass until the docs are updated).

Please update the forge-lint reference with your new lint + update the severity groups with the new one for codesize-related lints.

[0xClandestine]

@0xrusowsky foundry-rs/book#1614

[grandizzy]

thank you, overall lgtm, left couple of optional nits, pls check 🙏

[0xrusowsky]

@0xClandestine i'll take care of this round of feedback, as it is mostly targeted to the changes that i did to figure out the correct indentation 🤝

[grandizzy]

lgtm!