StrRetToBufW

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

HRESULT StrRetToBufW(
    STRRET* pstr,
    ITEMIDLIST* pidl,   // optional
    LPWSTR pszBuf,
    DWORD cchBuf
);

<DllImport("SHLWAPI.dll", CharSet:=CharSet.Unicode, ExactSpelling:=True)>
Public Shared Function StrRetToBufW(
    pstr As IntPtr,   ' STRRET* in/out
    pidl As IntPtr,   ' ITEMIDLIST* optional
    <MarshalAs(UnmanagedType.LPWStr)> pszBuf As System.Text.StringBuilder,   ' LPWSTR out
    cchBuf As UInteger   ' DWORD
) As Integer
End Function

' pstr : STRRET* in/out
' pidl : ITEMIDLIST* optional
' pszBuf : LPWSTR out
' cchBuf : DWORD
Declare PtrSafe Function StrRetToBufW Lib "shlwapi" ( _
    ByVal pstr As LongPtr, _
    ByVal pidl As LongPtr, _
    ByVal pszBuf As LongPtr, _
    ByVal cchBuf As Long) As Long
' 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

StrRetToBufW = ctypes.windll.shlwapi.StrRetToBufW
StrRetToBufW.restype = ctypes.c_int
StrRetToBufW.argtypes = [
    ctypes.c_void_p,  # pstr : STRRET* in/out
    ctypes.c_void_p,  # pidl : ITEMIDLIST* optional
    wintypes.LPWSTR,  # pszBuf : LPWSTR out
    wintypes.DWORD,  # cchBuf : DWORD
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('SHLWAPI.dll')
StrRetToBufW = Fiddle::Function.new(
  lib['StrRetToBufW'],
  [
    Fiddle::TYPE_VOIDP,  # pstr : STRRET* in/out
    Fiddle::TYPE_VOIDP,  # pidl : ITEMIDLIST* optional
    Fiddle::TYPE_VOIDP,  # pszBuf : LPWSTR out
    -Fiddle::TYPE_INT,  # cchBuf : DWORD
  ],
  Fiddle::TYPE_INT)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

#[link(name = "shlwapi")]
extern "system" {
    fn StrRetToBufW(
        pstr: *mut STRRET,  // STRRET* in/out
        pidl: *mut ITEMIDLIST,  // ITEMIDLIST* optional
        pszBuf: *mut u16,  // LPWSTR out
        cchBuf: u32  // DWORD
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("SHLWAPI.dll", CharSet = CharSet.Unicode)]
public static extern int StrRetToBufW(IntPtr pstr, IntPtr pidl, [MarshalAs(UnmanagedType.LPWStr)] System.Text.StringBuilder pszBuf, uint cchBuf);
"@
$api = Add-Type -MemberDefinition $sig -Name 'SHLWAPI_StrRetToBufW' -Namespace Win32 -PassThru
# $api::StrRetToBufW(pstr, pidl, pszBuf, cchBuf)

#uselib "SHLWAPI.dll"
#func global StrRetToBufW "StrRetToBufW" wptr, wptr, wptr, wptr
; StrRetToBufW varptr(pstr), varptr(pidl), varptr(pszBuf), cchBuf   ; 戻り値は stat
; pstr : STRRET* in/out -> "wptr"
; pidl : ITEMIDLIST* optional -> "wptr"
; pszBuf : LPWSTR out -> "wptr"
; cchBuf : 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 "SHLWAPI.dll"
#cfunc global StrRetToBufW "StrRetToBufW" var, var, var, int
; res = StrRetToBufW(pstr, pidl, pszBuf, cchBuf)
; pstr : STRRET* in/out -> "var"
; pidl : ITEMIDLIST* optional -> "var"
; pszBuf : LPWSTR out -> "var"
; cchBuf : DWORD -> "int"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

; HRESULT StrRetToBufW(STRRET* pstr, ITEMIDLIST* pidl, LPWSTR pszBuf, DWORD cchBuf)
#uselib "SHLWAPI.dll"
#cfunc global StrRetToBufW "StrRetToBufW" var, var, var, int
; res = StrRetToBufW(pstr, pidl, pszBuf, cchBuf)
; pstr : STRRET* in/out -> "var"
; pidl : ITEMIDLIST* optional -> "var"
; pszBuf : LPWSTR out -> "var"
; cchBuf : DWORD -> "int"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

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

var (
	shlwapi = windows.NewLazySystemDLL("SHLWAPI.dll")
	procStrRetToBufW = shlwapi.NewProc("StrRetToBufW")
)

// pstr (STRRET* in/out), pidl (ITEMIDLIST* optional), pszBuf (LPWSTR out), cchBuf (DWORD)
r1, _, err := procStrRetToBufW.Call(
	uintptr(pstr),
	uintptr(pidl),
	uintptr(pszBuf),
	uintptr(cchBuf),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // HRESULT

function StrRetToBufW(
  pstr: Pointer;   // STRRET* in/out
  pidl: Pointer;   // ITEMIDLIST* optional
  pszBuf: PWideChar;   // LPWSTR out
  cchBuf: DWORD   // DWORD
): Integer; stdcall;
  external 'SHLWAPI.dll' name 'StrRetToBufW';

result := DllCall("SHLWAPI\StrRetToBufW"
    , "Ptr", pstr   ; STRRET* in/out
    , "Ptr", pidl   ; ITEMIDLIST* optional
    , "Ptr", pszBuf   ; LPWSTR out
    , "UInt", cchBuf   ; DWORD
    , "Int")   ; return: HRESULT

●StrRetToBufW(pstr, pidl, pszBuf, cchBuf) = DLL("SHLWAPI.dll", "int StrRetToBufW(void*, void*, char*, dword)")
# 呼び出し: StrRetToBufW(pstr, pidl, pszBuf, cchBuf)
# pstr : STRRET* in/out -> "void*"
# pidl : ITEMIDLIST* optional -> "void*"
# pszBuf : LPWSTR out -> "char*"
# cchBuf : 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。