Function walk_guards 

fn walk_guards<'hir>(
    gcx: Gcx<'hir>,
    hir: &'hir Hir<'hir>,
    stmts: &'hir [Stmt<'hir>],
    recipient: VariableId,
    token: VariableId,
    delegations: &[FunctionId],
    unstable_code_delegations: &[FunctionId],
    bypass: bool,
    seen: &mut Vec<FunctionId>,
    walk: &mut GuardWalk,
)

Reads a body in statement order and judges the delegated mints against the guards. A code-less proof may cover a later delegation, but a callback must run after ownership is established to match _safeMint: the receiver can inspect ownerOf, balances, or reenter during the hook. Such a callback covers delegations still pending, the revert undoing them, unless a statement in between may leave the function successfully, keeping the unacknowledged token: super._mint(to, id); if (id == 0) return; require(hook...) walks out with token zero standing.

The recognized guard shapes are a closed set, because a hook call that merely appears inside a condition proves nothing about whether the revert depends on its answer. They are: require/assert on an acceptance condition, if (hook != selector) <exits>, if (hook == selector) {} else <exits>, and any of those reached through a function or modifier. A callback helper receives both identities, the way OpenZeppelin factors _checkOnERC721Received out of _safeMint; a code-less proof needs only the recipient.

Branches are read separately and merged: coverage holds only when every path checked, while a pending or escaping path taints the whole. The branch a to.code.length test dedicates to accounts starts covered, an account always accepting the token. A loop body may run zero times, so nothing in one is credited, while the delegations and escapes it may hold still count.

Everything else reports, a try whose catch may swallow the refusal included, and so are an answer stored in a local and a helper returning it as a bool. Following the value across statements would take a dataflow analysis this detector does not run.