Inconsistent use of int and size_t in C Bindings for std::vector Types #1089

NickUfer · 2024-12-03T14:36:36Z

The types ManifoldCrossSectionVec, ManifoldPolygon, ManifoldPolygons and ManifoldManifoldVec represent std::vector in the C bindings. However, their API functions mix the use of size_t and int for lengths and indices. For example:

ManifoldCrossSectionVec:

size_t manifold_cross_section_vec_length(ManifoldCrossSectionVec *csv); // uses size_t
ManifoldCrossSection *manifold_cross_section_vec_get(void *mem, ManifoldCrossSectionVec *csv, int idx); // uses int

SimplePolygon:

size_t manifold_simple_polygon_length(ManifoldSimplePolygon *p); // uses size_t
ManifoldVec2 manifold_simple_polygon_get_point(ManifoldSimplePolygon *p, int idx); // uses int

ManifoldPolygons:

size_t manifold_polygons_length(ManifoldPolygons *ps); // uses size_t
ManifoldSimplePolygon *manifold_polygons_get_simple(void *mem, ManifoldPolygons *ps, int idx); // uses int

ManifoldManifoldVec:

size_t manifold_manifold_vec_length(ManifoldManifoldVec *ms); // uses size_t
void manifold_manifold_vec_set(ManifoldManifoldVec *ms, int idx, ManifoldManifold *m); // uses int
ManifoldManifold *manifold_manifold_vec_get(void *mem, ManifoldManifoldVec *ms, int idx); // uses int

Problem

The use of int for indices is problematic because int cannot represent the full range of values that size_t can. This mismatch can lead to:

Potential bugs: Negative or out-of-range values for indices.
Type safety issues: Implicit conversions and sign mismatches.
Platform-specific inconsistencies: Differences in the size of int and size_t across platforms.

Suggested Solution

All int parameters used for indices in the API should be updated to size_t to ensure consistency with the std::vector representation and avoid these issues.
Would be open to contribute a fix 😄

The text was updated successfully, but these errors were encountered:

pca006132 · 2024-12-03T15:08:09Z

Yeah, this is probably some old code we forgot to change to size_t. PR is welcomed.

NickUfer mentioned this issue Dec 3, 2024

refactor(1089): update index types from int to size_t #1090

Merged

elalish closed this as completed in #1090 Dec 4, 2024

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Inconsistent use of int and size_t in C Bindings for std::vector Types #1089

Inconsistent use of int and size_t in C Bindings for std::vector Types #1089

Inconsistent use of int and size_t in C Bindings for std::vector Types #1089

Inconsistent use of int and size_t in C Bindings for std::vector Types #1089

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Problem

Suggested Solution