ExtractIconW

// SHELL32.dll  (Unicode / -W)
#include <windows.h>

HICON ExtractIconW(
    HINSTANCE hInst,   // optional
    LPCWSTR pszExeFileName,
    DWORD nIconIndex
);

<DllImport("SHELL32.dll", CharSet:=CharSet.Unicode, ExactSpelling:=True)>
Public Shared Function ExtractIconW(
    hInst As IntPtr,   ' HINSTANCE optional
    <MarshalAs(UnmanagedType.LPWStr)> pszExeFileName As String,   ' LPCWSTR
    nIconIndex As UInteger   ' DWORD
) As IntPtr
End Function

' hInst : HINSTANCE optional
' pszExeFileName : LPCWSTR
' nIconIndex : DWORD
Declare PtrSafe Function ExtractIconW Lib "shell32" ( _
    ByVal hInst As LongPtr, _
    ByVal pszExeFileName As LongPtr, _
    ByVal nIconIndex As Long) As LongPtr
' Unicode(W): 文字列は ByVal As LongPtr とし StrPtr(unicodeStr) を渡す
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

ExtractIconW = ctypes.windll.shell32.ExtractIconW
ExtractIconW.restype = ctypes.c_void_p
ExtractIconW.argtypes = [
    wintypes.HANDLE,  # hInst : HINSTANCE optional
    wintypes.LPCWSTR,  # pszExeFileName : LPCWSTR
    wintypes.DWORD,  # nIconIndex : DWORD
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('SHELL32.dll')
ExtractIconW = Fiddle::Function.new(
  lib['ExtractIconW'],
  [
    Fiddle::TYPE_VOIDP,  # hInst : HINSTANCE optional
    Fiddle::TYPE_VOIDP,  # pszExeFileName : LPCWSTR
    -Fiddle::TYPE_INT,  # nIconIndex : DWORD
  ],
  Fiddle::TYPE_VOIDP)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

#[link(name = "shell32")]
extern "system" {
    fn ExtractIconW(
        hInst: *mut core::ffi::c_void,  // HINSTANCE optional
        pszExeFileName: *const u16,  // LPCWSTR
        nIconIndex: u32  // DWORD
    ) -> *mut core::ffi::c_void;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("SHELL32.dll", CharSet = CharSet.Unicode)]
public static extern IntPtr ExtractIconW(IntPtr hInst, [MarshalAs(UnmanagedType.LPWStr)] string pszExeFileName, uint nIconIndex);
"@
$api = Add-Type -MemberDefinition $sig -Name 'SHELL32_ExtractIconW' -Namespace Win32 -PassThru
# $api::ExtractIconW(hInst, pszExeFileName, nIconIndex)

#uselib "SHELL32.dll"
#func global ExtractIconW "ExtractIconW" wptr, wptr, wptr
; ExtractIconW hInst, pszExeFileName, nIconIndex   ; 戻り値は stat
; hInst : HINSTANCE optional -> "wptr"
; pszExeFileName : LPCWSTR -> "wptr"
; nIconIndex : DWORD -> "wptr"
; ※HSP3.7は #func のため戻り値はシステム変数 stat に格納されます。

#uselib "SHELL32.dll"
#cfunc global ExtractIconW "ExtractIconW" sptr, wstr, int
; res = ExtractIconW(hInst, pszExeFileName, nIconIndex)
; hInst : HINSTANCE optional -> "sptr"
; pszExeFileName : LPCWSTR -> "wstr"
; nIconIndex : DWORD -> "int"

; HICON ExtractIconW(HINSTANCE hInst, LPCWSTR pszExeFileName, DWORD nIconIndex)
#uselib "SHELL32.dll"
#cfunc global ExtractIconW "ExtractIconW" intptr, wstr, int
; res = ExtractIconW(hInst, pszExeFileName, nIconIndex)
; hInst : HINSTANCE optional -> "intptr"
; pszExeFileName : LPCWSTR -> "wstr"
; nIconIndex : DWORD -> "int"

import (
	"golang.org/x/sys/windows"
	"unsafe"
)

var (
	shell32 = windows.NewLazySystemDLL("SHELL32.dll")
	procExtractIconW = shell32.NewProc("ExtractIconW")
)

// hInst (HINSTANCE optional), pszExeFileName (LPCWSTR), nIconIndex (DWORD)
r1, _, err := procExtractIconW.Call(
	uintptr(hInst),
	uintptr(unsafe.Pointer(windows.StringToUTF16Ptr(pszExeFileName))),
	uintptr(nIconIndex),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // HICON

function ExtractIconW(
  hInst: THandle;   // HINSTANCE optional
  pszExeFileName: PWideChar;   // LPCWSTR
  nIconIndex: DWORD   // DWORD
): THandle; stdcall;
  external 'SHELL32.dll' name 'ExtractIconW';

result := DllCall("SHELL32\ExtractIconW"
    , "Ptr", hInst   ; HINSTANCE optional
    , "WStr", pszExeFileName   ; LPCWSTR
    , "UInt", nIconIndex   ; DWORD
    , "Ptr")   ; return: HICON

●ExtractIconW(hInst, pszExeFileName, nIconIndex) = DLL("SHELL32.dll", "void* ExtractIconW(void*, char*, dword)")
# 呼び出し: ExtractIconW(hInst, pszExeFileName, nIconIndex)
# hInst : HINSTANCE optional -> "void*"
# pszExeFileName : LPCWSTR -> "char*"
# nIconIndex : DWORD -> "dword"
# なでしこ1は32bit・ANSI(Shift_JIS)。文字列=char*(ANSI)、ポインタ/ハンドル=void*(4byte)。
# ※-W(Unicode)関数。なでしこ1はANSIのため -A 版の利用を推奨。