Use Ref for lpMsgBuf (#20051)

* Use Ref for lpMsgBuf

* Prettify

Author: musm

base/libc.jl

@@ -270,23 +270,23 @@ Convert a Win32 system call error code to a descriptive string [only available o
 function FormatMessage end
 
 if is_windows()
-    GetLastError() = ccall(:GetLastError,stdcall,UInt32,())
+    GetLastError() = ccall(:GetLastError, stdcall, UInt32, ())
 
     function FormatMessage(e=GetLastError())
         const FORMAT_MESSAGE_ALLOCATE_BUFFER = UInt32(0x100)
         const FORMAT_MESSAGE_FROM_SYSTEM = UInt32(0x1000)
         const FORMAT_MESSAGE_IGNORE_INSERTS = UInt32(0x200)
         const FORMAT_MESSAGE_MAX_WIDTH_MASK = UInt32(0xFF)
-        lpMsgBuf = Array{Ptr{UInt16},0}()
-        lpMsgBuf[1] = 0
-        len = ccall(:FormatMessageW,stdcall,UInt32,(Cint, Ptr{Void}, Cint, Cint, Ptr{Ptr{UInt16}}, Cint, Ptr{Void}),
+        lpMsgBuf = Ref{Ptr{UInt16}}()
+        lpMsgBuf[] = 0
+        len = ccall(:FormatMessageW, stdcall, UInt32, (Cint, Ptr{Void}, Cint, Cint, Ptr{Ptr{UInt16}}, Cint, Ptr{Void}),
                     FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_MAX_WIDTH_MASK,
                     C_NULL, e, 0, lpMsgBuf, 0, C_NULL)
-        p = lpMsgBuf[1]
+        p = lpMsgBuf[]
         len == 0 && return ""
         buf = Array{UInt16}(len)
         unsafe_copy!(pointer(buf), p, len)
-        ccall(:LocalFree,stdcall,Ptr{Void},(Ptr{Void},),p)
+        ccall(:LocalFree, stdcall, Ptr{Void}, (Ptr{Void},), p)
         return transcode(String, buf)
     end
 end