Migration Validator

Migration Validation Checklist

Compilation Check

• [ ] Rust code compiles with rustc --edition 2024
• [ ] No errors, only warnings acceptable if minor
• [ ] Clippy passes with 0 warnings (cargo clippy)

Safety Check

• [ ] Count unsafe blocks (target: 0 for easy/medium, minimize for hard)
• [ ] Every unsafe block has a // SAFETY: comment
• [ ] No raw pointer dereferences without bounds checking
• [ ] No transmute unless absolutely necessary
• [ ] No unwrap() on user-controlled data

Semantic Equivalence

• [ ] Same function signature (equivalent types)
• [ ] Same behavior for all valid inputs
• [ ] Same error conditions / edge cases
• [ ] Overflow behavior matches (wrapping vs. checked)
• [ ] Printf format matches exactly (especially %g → custom format_g())
• [ ] Bool/int distinction preserved (C int 0/1 ≠ Rust bool)

Differential Testing

• [ ] Compile C with cc -std=gnu11 -lm
• [ ] Compile Rust with rustc --edition 2024
• [ ] Run both with identical test inputs
• [ ] Compare outputs byte-by-byte (not just "looks similar")
• [ ] Test edge cases: empty input, max values, null/None, negative numbers
• [ ] Float tolerance: exact match preferred, tolerance only for known precision differences

Idiomatic Score

Enhanced formula with positive AND negative signals:

• Base: 100
• Negative: - (unsafe_blocks * 10) - (clippy_warnings * 2) - (unwrap_count * 3) - (as_casts * 1)
• Positive: + min(10, result_count * 2) + min(5, option_count) + min(5, iter_usage)
• Ranges: 90-100 Excellent, 70-89 Good, 60-69 Acceptable, high-score non-compiling > c2rust fallback

Repair Loop Rules

• Effective iterations scale with file size:
• 2000 LOC: min(configured, 2)
• Chunked translations: max(configured, 8) — chunks are small, repair is affordable
• Stall detection: 2 unchanged error counts → re-translate at temp 0.7
• Temperature ramp: base 0.2 + 0.1 per iteration (capped at 1.0)
• Quality gate: if initial translation has >5 unsafe → re-translate at temp 0.5
• P5: Idiomatic hints — when compiles + diff passes but score < threshold, repair agent gets refactoring hints instead of empty feedback (prevents wasted iterations)

Validated Production Migrations

These fixtures are regression-tested and represent known-good migrations: | File | LOC C→Rust | Score | Unsafe | Notes | |------|-----------|-------|--------|-------| | add, power, gcd, etc. | <50 | 100 | 0 | Simple arithmetic | | hashtable.c | 204→~200 | 81 | 0 | malloc/free → Box/Vec | | cjsoncombined.c | 520→319 | 100 | 0 | JSON parser, recursive data | | expreval.c | 1686→1446 | 100 | 0 | 74 functions, recursive descent | | cjsonfullcombined.c | 1696→1439 | 100* | 0 | Full cJSON library (49/78 fns) | | picohttpparser.c | 1102→1551 | 100 | 0 | HTTP parser, state machine | | genanncombined.c | 642→622 | 100 | 0 | Neural network, fn ptrs→enum, autonomous pipeline | | olivecombined.c | 1443→1176 | 100 | 0 | 2D graphics, pixel buffers, checksum diff test | | httpparsercombined.c | 3680→1492 | N/A | 0 | HTTP parser, goto state machine→line parsing, manual completion | | minizcore_standalone.c | 4429 | N/A | N/A | FallbackUnsafe (ceiling case) |

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Powered by Noricum — autonomous C/C++ to Rust migration agent

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: JuanMarchetto
• Source: JuanMarchetto/agent-skills
• License: MIT
• Homepage: https://github.com/JuanMarchetto/agent-skills

Install and usage instructions live in the source repository linked above.