27bb4d807f
- 12 detector ideas across 4 categories - Phase 1 (S effort): deprecated APIs, throwing dtors, missing noexcept - Phase 2 (M-L): use-after-move, iterator invalidation, lock inversion - All phase 1 detectors are syntactic (RecursiveASTVisitor, no Z3 needed)
94 lines
2.6 KiB
Markdown
94 lines
2.6 KiB
Markdown
# Code Quality Detector Opportunities for fold
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> Generated 2026-05-29. Research on non-memory-safety detectors fold could add.
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## API Misuse Detectors
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### 1. Missing std::move on return (Z3)
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```cpp
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// BAD: copies unnecessarily
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std::string foo() {
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std::string s = build();
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return s; // copy — should be std::move(s) or RVO
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}
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```
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Z3 query: prove that a local variable is returned without move and without RVO eligibility.
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### 2. Use-after-move (Z3)
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```cpp
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// BAD: reading moved-from value
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auto x = std::move(y);
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y.size(); // UB: y was moved
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```
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Z3 query: prove that a moved-from object is accessed on some path.
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### 3. Missing std::forward (Syntactic)
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```cpp
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// BAD: forwarding reference not forwarded
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template<typename T> void wrap(T&& x) {
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foo(x); // should be foo(std::forward<T>(x))
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}
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```
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### 4. Iterator invalidation (Z3)
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```cpp
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// BAD: iterator used after container mutation
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auto it = v.begin();
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v.push_back(42); // may invalidate it
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*it = 7; // UB
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```
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## Exception Safety Detectors
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### 5. Throwing destructor (Syntactic)
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```cpp
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// BAD: destructor may throw
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~File() { close(); } // if close() throws, std::terminate
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```
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### 6. Missing noexcept on move (Syntactic)
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```cpp
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// BAD: move not noexcept may prevent vector growth optimization
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MyType(MyType&& other) : data(other.data) {} // missing noexcept
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```
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## Concurrency Detectors
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### 7. Data race on non-atomic (Z3)
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```cpp
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// BAD: unguarded shared state
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int shared = 0;
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// Thread A: shared++; // UB: data race
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```
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### 8. Lock inversion (Z3)
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```cpp
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// BAD: inconsistent lock ordering
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std::lock(mu1, mu2); // first path
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std::lock(mu2, mu1); // second path — deadlock potential
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```
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## Deprecated API Detection (Syntactic)
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| API | Replacement | Severity |
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|-----|-------------|----------|
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| `std::auto_ptr` | `std::unique_ptr` | High |
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| `rand()` | `<random>` | Medium |
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| `gets()` | `fgets()` | Critical |
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| `sprintf()` | `snprintf()` | High |
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| `strcpy()` | `strncpy()` / `std::string` | High |
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| `::bind()` (old API) | `::bind()` (new) | Low |
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## Implementation Priority
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| Priority | Detector | Effort | Expected False Positives |
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|----------|----------|--------|--------------------------|
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| 1 | Deprecated API (syntactic) | S | Very low |
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| 2 | Throwing destructor | S | Very low |
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| 3 | Missing noexcept on move | S | Low |
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| 4 | Missing std::move on return | M | Medium |
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| 5 | Use-after-move | L | Medium |
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| 6 | Iterator invalidation | L | High |
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| 7 | Lock inversion | L | High |
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Phase 1-2 detectors (4 items, ~200 lines total) could be added as RecursiveASTVisitor-based syntactic detectors — no Z3 needed. This follows the same pattern as the existing `deprecated_api.cpp` detector.
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