Fix dead-code detector incorrectly flagging library functions

[ep0chzer0]

Summary

• Fixes bug where library functions used via using X for Y syntax were incorrectly reported as dead code
• Corrects type annotation and indexing error in dead-code detector

Details

The dead-code detector had a bug in how it tracked library function usage:

# Before (incorrect):
all_libs_called: list[tuple[Contract, Function]] = [
    item.function for sublist in all_libss_called for item in sublist
]
functions_used |= {
    lib[1].canonical_name for lib in all_libs_called if isinstance(lib, tuple)
}

# After (correct):
all_libs_called: list[Function] = [
    item.function for sublist in all_libss_called for item in sublist
]
functions_used |= {
    f.canonical_name for f in all_libs_called if isinstance(f, Function)
}

The issue was that all_library_calls() returns LibraryCall objects, and item.function extracts a Function object, not a tuple. The code was trying to index lib[1] on a Function object, which would fail.

Test plan

• Added test case with library using using X for Y syntax
• Test includes both used and unused library functions to verify correct detection

Fixes #1265

🤖 Generated with Claude Code

[ep0chzer0]

Hello maintainers! This fixes a bug in the dead-code detector where library functions used via using X for Y syntax were incorrectly flagged as dead code. The fix corrects a type annotation and indexing error. Could you please approve the CI workflows to run? Thank you!

[dguido]

Bulk PR Review Summary

Research Findings

• Issue Fixed: [Bug]: Slither incorrectly reports internal library function as unused #1265 - Dead-code detector incorrectly flags library functions as unused when used via using X for Y syntax
• Root Cause: Type annotation mismatch where all_libs_called was annotated as list[tuple[Contract, Function]] but actually contained Function objects, causing isinstance(lib, tuple) to always be False

Code Review

The fix is correct:

# Before (broken):
all_libs_called: list[tuple[Contract, Function]] = [...]
functions_used |= {lib[1].canonical_name for lib in all_libs_called if isinstance(lib, tuple)}

# After (fixed):
all_libs_called: list[Function] = [...]
functions_used |= {f.canonical_name for f in all_libs_called if isinstance(f, Function)}

Test Status

• ✅ Merged with master (no conflicts)
• ✅ Dead-code detector tests pass (2/2)
• ✅ Linting passes
• ✅ Snapshot file confirms no false positives for library functions

Merge Readiness

Ready to merge - The fix correctly addresses issue #1265 and all tests pass.

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🤖 Automated review by Claude