[luhrhenzthedev]

Fix interprocedural storage TOCTOU detection for qualified Self:: calls

Problem

cargo test -p soroban-guard-checks failed on main:

---- interprocedural_storage_toctou::tests::flags_claim_do_claim_split stdout ----
thread 'interprocedural_storage_toctou::tests::flags_claim_do_claim_split' panicked at
crates/checks/src/interprocedural_storage_toctou.rs:300:9:
assertion `left == right` failed: should flag the TOCTOU pattern
  left: 0
 right: 1

The check was registered and running, but it returned 0 findings on a fixture that clearly demonstrates the split-function TOCTOU pattern: claim() reads storage via already_claimed(), then writes storage via do_claim(). Because the read and write happen in different functions, the guard in claim() does not protect the write in do_claim().

Root Cause

In collect_ops_visitor, visit_expr_call extracted the callee name using:

if let Some(ident) = p.path.get_ident() {
    let callee = ident.to_string();

get_ident() only returns Some for simple, unqualified identifiers (e.g., foo()). For qualified calls like Self::already_claimed(&env) or Self::do_claim(&env), the path is Path with multiple segments, so get_ident() returns None. As a result, the visitor never descended into called helper functions, and their storage operations were never collected. With no writes collected, the read/write matching logic had nothing to flag.

Fix

Changed callee extraction to use the last segment of the path:

if let Some(segment) = p.path.segments.last() {
    let callee = segment.ident.to_string();

This works for both:

• Unqualified calls: foo() → segment foo
• Qualified calls: Self::foo() → segment foo

Now the interprocedural visitor correctly traverses into helper functions and collects their storage reads/writes, allowing the TOCTOU pattern to be detected.

Verification

cargo test -p soroban-guard-checks --lib

Result: 741 passed; 0 failed

The previously failing test now passes, and all existing tests continue to pass.

Files Changed

• crates/checks/src/interprocedural_storage_toctou.rs

closes #441