Fixing eastl's variant.

[nicolasnoble]

Summary by CodeRabbit

• Refactor
  • Updated type definitions in EASTL's variant implementation to use EASTL_SSIZE_T instead of ssize_t
  • Improved type safety and consistency in variant type handling

[coderabbitai]

Walkthrough

The pull request introduces modifications to the variant.h file in the EASTL library, focusing on type consistency for template parameters. The changes replace the ssize_t type with EASTL_SSIZE_T in function signatures for holds_alternative and the assignment operator. This update ensures type safety and alignment with EASTL's type definitions, maintaining the core functionality of the variant class while improving type handling.

Changes

File	Change Summary
third_party/EASTL/include/EASTL/variant.h	- Replaced ssize_t with EASTL_SSIZE_T in template parameter types - Updated method signatures for holds_alternative and assignment operator - Maintained overall variant class structure and functionality

Poem

🐰 A Variant's Tale of Type Delight

In EASTL's realm, where types take flight,
EASTL_SSIZE_T shines so bright,
Replacing ssize_t with grace and might,
Our variant dances, type-safe and light! 🌟

Hop, hop, hurray for type precision! 🎉

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📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 0933dcd and bc4529d.

📒 Files selected for processing (1)

• third_party/EASTL/include/EASTL/variant.h (2 hunks)

🔇 Additional comments (2)

third_party/EASTL/include/EASTL/variant.h (2)

861-861: Consistent application of EASTL_SSIZE_T for the variant assignment operator.
This change aligns the index type in the assignment operator template parameter with the rest of the library’s variant semantics. It helps keep the logic consistent when the index can potentially be negative, matching the pattern used in holds_alternative.

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640-643: Validate handling of negative indices in EASTL_SSIZE_T.
Using a signed index type here allows for sentinel values, yet it is crucial to confirm that no undefined behavior occurs if I becomes negative in meta::get_type_index_v. Please ensure that negative values are truly expected and gracefully handled throughout the codebase.

To verify, consider searching for all consumers of holds_alternative and checking downstream code paths for assumptions about non-negative indices.

✅ Verification successful

Let me check the implementation of meta::get_type_index_v to understand how negative indices are handled.

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Let me check the implementation of get_type_index to understand how it handles types not found in the type list.

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Let me check the meta.h file directly to see the implementation.

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Negative indices in holds_alternative are safely handled

After analyzing the implementation, I can confirm that negative indices are properly handled:

1. meta::get_type_index_v returns -1 when a type is not found in the type list (as seen in the get_type_index<I, T> specialization).
2. The holds_alternative function explicitly handles this case by comparing against variant_npos (which is defined as size_t(-1)).
3. The implementation return I == variant_npos ? false : (v.index() == I) safely handles negative indices by returning false when I is -1.

The test cases in TestVariant.cpp confirm this behavior, particularly the tests that verify queries for types not in the variant's type list return false.

🏁 Scripts executed

The following scripts were executed for the analysis:

Script:

#!/bin/bash
# Example command to find usage that expects non-negative indices:
rg -A 4 "holds_alternative"

Length of output: 9925

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Script:

#!/bin/bash
# Search for get_type_index_v implementation
ast-grep --pattern 'get_type_index_v'

# Also search for variant_npos definition
rg "variant_npos" -A 2

Length of output: 4606

---

Script:

#!/bin/bash
# Search for get_type_index implementation
ast-grep --pattern 'struct get_type_index'

# Also search for any static_assert related to get_type_index
rg "static_assert.*get_type_index"

Length of output: 561

---

Script:

#!/bin/bash
# Look at the meta.h implementation
cat third_party/EASTL/include/EASTL/meta.h

Length of output: 8521

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