[CRITICAL BUG] dynarray_set() uses wrong casting instead of memcpy

[seesee010]

Bug Description

The dynarray_set() function has a critical casting bug that makes it only work for DynArray pointer types, breaking generic functionality.

Location

src/access.c line 34

Current Code

bool dynarray_set(DynArray *array, size_t index, void *value) {
    if (array == NULL) {
        return false;
    }

    if (index >= array->capacity) {
        array->length++;
        return false;
    }

    // i hate myself
    ((DynArray **)array->data)[index] = (DynArray*)value;  // ← WRONG!

    return true;
}

Problem

1. Casts generic void* to DynArray**
2. Only works if storing DynArray pointers
3. For ANY other type (int, float, struct), this causes undefined behavior
4. Should use memcpy() to copy element_size bytes

Expected Behavior

Should copy the actual data bytes, not cast pointers.

Proposed Fix

bool dynarray_set(DynArray *array, size_t index, void *value) {
    if (array == NULL || value == NULL) {
        return false;
    }

    if (index >= array->capacity) {
        return false;
    }

    // Proper generic set using memcpy
    void *dest = (char*)array->data + index * array->element_size;
    memcpy(dest, value, array->element_size);
    
    // Update length if setting beyond current length
    if (index >= array->length) {
        array->length = index + 1;
    }

    return true;
}

Impact

• Severity: Critical
• Any code using set() with non-pointer types will corrupt memory
• Makes the library unusable for its intended generic purpose

Test Case

DynArray *arr = dynarray_create(sizeof(int), 10);
int value = 42;
dynarray_set(arr, 0, &value);  // Currently broken for int types