Generic-Specific-HasFlag.cs

using System;
using System.IO;
using SharpLab.Runtime;

static class X
{
    public static bool HasFlag(this FileAttributes self, FileAttributes flag) =>
        (self & flag) == flag;

    [JitGeneric(typeof(FileAttributes))]
    public static bool HasFlag<T>(this T self, T flag) where T : Enum, IConvertible =>
        (self.ToInt32(null) & flag.ToInt32(null)) == flag.ToInt32(null);
}

​Generic-Specific-HasFlag.jit.asm

; Core CLR v4.700.19.46205 (coreclr.dll) on x86.

X.HasFlag(System.IO.FileAttributes, System.IO.FileAttributes)
    L0000: and ecx, edx
    L0002: cmp ecx, edx
    L0004: setz al
    L0007: movzx eax, al
    L000a: ret

X.HasFlag[[System.IO.FileAttributes, System.Runtime]](System.IO.FileAttributes, System.IO.FileAttributes)
    L0000: push ebp
    L0001: mov ebp, esp
    L0003: push edi
    L0004: push esi
    L0005: push ebx
    L0006: push eax
    L0007: mov edi, ecx
    L0009: mov esi, edx
    L000b: mov ecx, 0x111b15a0
    L0010: call 0x31c30cc
    L0015: mov ebx, eax
    L0017: mov [ebx+0x4], edi
    L001a: mov ecx, 0x111b15a0
    L001f: call 0x31c30cc
    L0024: mov edi, eax
    L0026: mov ecx, ebx
    L0028: xor edx, edx
    L002a: call dword [0x33309d4]
    L0030: mov ebx, eax
    L0032: mov [edi+0x4], esi
    L0035: mov ecx, 0x111b15a0
    L003a: call 0x31c30cc
    L003f: mov [ebp-0x10], eax
    L0042: mov ecx, edi
    L0044: xor edx, edx
    L0046: call dword [0x33309d4]
    L004c: and ebx, eax
    L004e: mov edi, [ebp-0x10]
    L0051: mov [edi+0x4], esi
    L0054: mov ecx, edi
    L0056: xor edx, edx
    L0058: call dword [0x33309d4]
    L005e: cmp eax, ebx
    L0060: setz al
    L0063: movzx eax, al
    L0066: pop ecx
    L0067: pop ebx
    L0068: pop esi
    L0069: pop edi
    L006a: pop ebp
    L006b: ret

​​.sharplab.json

{
    "version": 1,
    "target": "JIT ASM",
    "mode": "Release",
    "branch": "features-local-function-attributes"
}