Marshal.SizeOf of bool and char report wrong value

[MichalStrehovsky]

Their results seem to vary too:

using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

Console.WriteLine($"[bool] unsafe: {Unsafe.SizeOf<bool>()}, marshal: {Marshal.SizeOf<bool>()}");
Console.WriteLine($"[char] unsafe: {Unsafe.SizeOf<char>()}, marshal: {Marshal.SizeOf<char>()}");

CoreCLR:

[bool] unsafe: 1, marshal: 1
[char] unsafe: 2, marshal: 2

Native AOT:

[bool] unsafe: 1, marshal: 4
[char] unsafe: 2, marshal: 1

.NET 9 and 10p3

Originally posted by @am11 in #113589

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[MichalStrehovsky]

This is a very old bug. TODO for it was added in dotnet/corert#5707 (comment).

I'm actually not sure where the worms are, I would fix it by adding is primitive and not bool or char but we could have done that 7 years ago too so I'm likely missing context... so just filing as a bug.

[jkotas]

I would fix it by adding is primitive and not bool or char

I think it would be fine if it fixed this bug, but I doubt that it is going to fix the problem.

NativeAOT returning 4 for bool means that it is treated as marshalled, but CoreCLR treats it as blittable (?).

[MichalStrehovsky]

NativeAOT returning 4 for bool means that it is treated as marshalled, but CoreCLR treats it as blittable (?).

I think @am11 has the results swapped, I'm seeing this on CoreCLR:

[bool] unsafe: 1, marshal: 4
[char] unsafe: 2, marshal: 1

And this on native AOT:

[bool] unsafe: 1, marshal: 1
[char] unsafe: 2, marshal: 2

I.e. it's marshalled on CoreCLR, but blittable on native AOT.

[am11]

I think @am11 has the results swapped

Ah, I copied nativeaot output first. (in my defense, it was late at night and I was focused on 32 byte delta when this other difference showed up 😅)