Reproduction steps:
1. Open the attached project "Project"
2. Attach “Assets/OverflowTest.cs“ to “MainCamera” GameObject
3. Enter the Play mode
4. Observe the console

Expected result: HashSet is created and memory is allocated for it
Actual result: InvalidOperation error is thrown or Editor crashes if the size is increased

Reproducible with: 2.4.2 (2022.3.39f1, 6000.0.12f1)
Couldn’t test with: 1.2.4 (2021.3.40f1) - (error CS0246: The type or namespace name 'NativeParallelHashSet<>' could not be found )

Reproducible on: Windows 10
Not reproducible on: No other environment tested

Notes:
Crashes when allocating a larger HashSet (double the initial capacity in OverflowTest.cs to reproduce the crash)
Calculations in the CalculateDataSize function in UnsafeParallelHashMap.cs appear to hit the integer limit which causes a negative value to be returned, changing var to long resolves the error, this can be seen in the “ProjectWithEditedHashSet“ project, the crash still occurs with the increased size though

First few lines of stack trace:

{noformat}0x00007FFBB304C68E (Unity) memcpy
0x00007FFBAF83FC11 (Unity) UnsafeUtility_CUSTOM_MemCpy
0x000001CBA100FD88 (Mono JIT Code) (wrapper managed-to-native) Unity.Collections.LowLevel.Unsafe.UnsafeUtility:MemCpy (void,void,long)
0x000001CC6D4E2B5B (Mono JIT Code) [.\Library\PackageCache\com.unity.collections\Unity.Collections\UnsafeParallelHashMap.cs:175] Unity.Collections.LowLevel.Unsafe.UnsafeParallelHashMapData:ReallocateHashMap<short3, bool> (Unity.Collections.LowLevel.Unsafe.UnsafeParallelHashMapData*,int,int,Unity.Collections.AllocatorManager/AllocatorHandle)
0x000001CC6D4E2953 (Mono JIT Code) [.\Library\PackageCache\com.unity.collections\Unity.Collections\UnsafeParallelHashMap.cs:1196] Unity.Collections.LowLevel.Unsafe.UnsafeParallelHashMap`2<short3, bool>:set_Capacity (int)
0x000001CC6D4E2893 (Mono JIT Code) [.\Library\PackageCache\com.unity.collections\Unity.Collections\NativeParallelHashMap.cs:169] Unity.Collections.NativeParallelHashMap`2<short3, bool>:set_Capacity (int)
0x000001CC6D4E2763 (Mono JIT Code) [.\Library\PackageCache\com.unity.collections\Unity.Collections\NativeParallelHashSet.cs:71] Unity.Collections.NativeParallelHashSet`1<short3>:set_Capacity (int) {noformat}