Audit Changes for v1.4.1-2

[remedcu]

This PR makes the changes based on Certora's audit report for the Safe Migration Contracts. Changes are only made to the SafeToL2Migration contract. Most of the changes are related to reducing gas consumption, typos and comments.

[coveralls]

Pull Request Test Coverage Report for Build 10510138697

Details

• 20 of 20 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 94.196%

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Totals
Change from base Build 10081005354:	0.1%
Covered Lines:	386
Relevant Lines:	401

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💛 - Coveralls

[remedcu]

Open Question:

To maintain consistency, should we also rename this variable:

safe-smart-account/contracts/libraries/SafeToL2Setup.sol

Line 19 in e69f6f0

address public immutable _SELF;

From _SELF to SELF?

Update: Made that change, please let me know if it should be reverted.

[nlordell]

I wonder if we need to add unit tests for this? From a FV perspective we could in theory prove that the two always return the same. May be overkill for the audit PR, but might be nice to include on main.

[remedcu]

We could add that to the PR created for main. Won't prefer adding it to this one as you mentioned.

[nlordell]

LGTM, some small nits and an open question about how best to test the getOwners method.

[akshay-ap]

Typo still needs to be fixed: https://github.com/safe-global/safe-smart-account/pull/812/files#diff-925588b812f729cc164d14a48e571ce813e2f0ae6f5c5420fc0382c767287fd0R135