Documentation Inconsistency: SuppressGCTransition Usage Scope

[Liangjia0411]

Issue Description

There is a discrepancy between the official documentation for SuppressGCTransition and its actual implementation. The documentation states this attribute can only be used with methods marked with DllImportAttribute, but in practice, it can also be used with delegate* unmanaged function pointer types.

Incorrect Documentation

This attribute is ignored if applied to a method without the DllImportAttribute.

Actual Implementation

In the C# 9.0 function pointers implementation, SuppressGCTransition is already supported as a calling convention modifier for delegate* unmanaged types, as shown in the C# 9.0 function pointers proposal documentation:

delegate* unmanaged[Cdecl, SuppressGCTransition]<int, int> ptr;

[huoyaoyuan]

It's not SuppressGCTransitionAttribute used in function pointer. It's CallConvSuppressGCTransition. Function pointers can be marked with special types with CallConv prefix. They don't use attribute types, although the syntax is similar.

You can see it's definition by hovering in Visual Studio: