Incorrect PInvoke definition will implicitly modify context local variable

[Gascognya]

Description

About libsdl-org/SDL C# bindings by PInvoke.

public static void Main()
{
    SDL_CreateWindow("Demo", 800, 600, 0);

    var loop = true;
    
    while (loop)
    {
        Console.WriteLine(loop); // True
        SDL_PollEvent(out _);
        Console.WriteLine(loop); // False
    }
}

public static void Main()
{
    SDL_CreateWindow("Demo", 800, 600, 0);

    var a = true;
    var b = true;
    var c = true;
    
    while (a || b || c)
    {
        Console.WriteLine($"before: a:{a}, b:{b}, c:{c}");
        SDL_PollEvent(out _);
        Console.WriteLine($"after: a:{a}, b:{b}, c:{c}");
    }
}

it's infinite loop, but broken.

before: a:True, b:True, c:True
after: a:True, b:True, c:False
before: a:True, b:True, c:False
after: a:True, b:True, c:False
before: a:True, b:True, c:False
after: a:False, b:False, c:False

Bug only occurs when the out parameter type definitions are inconsistent.

struct SDL_Event;

[return: MarshalAs(UnmanagedType.I1)]
[LibraryImport("SDL3")]
private static partial bool SDL_PollEvent(out SDL_Event evt);

The true definitions. it's large c union.
https://wiki.libsdl.org/SDL3/SDL_Event

Reproduction Steps

PInvokeSDL.zip

Expected behavior

infinite loop.

Actual behavior

infinite loop was broken.

Regression?

.net 8 and .net 9

Known Workarounds

no

Configuration

.net 8 and .net 9
windows 10
x64

Other information

No response

[huoyaoyuan]

out parameters are allocated on the stack and passed by reference. If its size is incorrect, native code accessing it will overwrite other memory on the stack, including return address.

The behavior is expected. Incorrect P/Invoke definition is unsafe and will corrupt things.

[Gascognya]

out parameters are allocated on the stack and passed by reference. If its size is incorrect, native code accessing it will overwrite other memory on the stack, including return address.

The behavior is expected. Incorrect P/Invoke definition is unsafe and will corrupt things.

that sounds crazy... and thank you bro