Easy enough fix to the batch file to solve this. Several fixes like this:

existing code:
echo: >> windows.h

fix:
echo:>> windows.h

When I open files in my editor it highlights trailing whitespace so it's a bit annoying to me personally. I have it solved locally and can submit a PR if interested.

This is from an older verison, so might not be 100% up to date:

CompareFileTime
WIN32_FILE_ATTRIBUTE_DATA
GET_FILEEX_INFO_LEVELS
GetFileAttributesExA
MAXDWORD

You're copying directly from the Windows SDK but the license only allows use of those headers and not modification or public distribution. Projects like mingw, Wine, and ReactOS avoid this problem by either doing a clean-room re-implementation or using the MSDN docs.

I was hoping to use this library this in a public-domain project I'm working on, but obviously the copyright violation prevents me. I'm going to continue with my original plan of writing a miniature public domain Windows.h for my own use. If you like, I will send patches that I know are not contaminated by the Microsoft license. With enough incremental changes the entire library would be fixed.

SecureZeroMemory function is inlined in microsofts headers so WindowsHModular should also embed the implementation.

For details, SecureZeroMemory is a macro defined in WinBase.h (C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\WinBase.h):

#define SecureZeroMemory RtlSecureZeroMemory

and RtlSecureZeroMemory is defined in winnt.h

FORCEINLINE
PVOID
RtlSecureZeroMemory(
    _Out_writes_bytes_all_(cnt) PVOID ptr,
    _In_ SIZE_T cnt
    )
{
    volatile char *vptr = (volatile char *)ptr;

#if defined(_M_AMD64)

    __stosb((PBYTE )((DWORD64)vptr), 0, cnt);

#else

    while (cnt) {

#if !defined(_M_CEE) && (defined(_M_ARM) || defined(_M_ARM64))

        __iso_volatile_store8(vptr, 0);

#else

        *vptr = 0;

#endif

        vptr++;
        cnt--;
    }

#endif // _M_AMD64

    return ptr;
}

This was the whole list for me. I generated it a while back, so it's possible there's more now:

HDC
HGLRC
APIENTRY
VOID
DECLARE_HANDLE
FLOAT
INT64
INT32

The original copyright header has lost

Copyright (c) Microsoft Corporation. All rights reserved.

The source provenance unclear.

win32\windows.h(941): error C2061: syntax error: identifier 'FLOATING_SAVE_AREA'

There's a mostly drop-in windows.h replacement (made by another user) which adds transparent UTF-8 support to ANSI Win32 programs, but as awesome as it is, it currently conflicts with WindowsHModular. Here is the repository in question, for review:

• https://github.com/thpatch/win32_utf8

There is also a related repository, which adds dynamic layout functionality for Win32 dialogues, but it is dependent on Win32_utf8:

• https://github.com/thpatch/win32_smartdlg

Also the adjacant error definition, ERROR_PIPE_BUSY is missing.

I think that these are the ones that needs adding:

#define ERROR_PIPE_BUSY 231L
BOOL WINAPI WaitNamedPipeA(LPCSTR lpNamedPipeName, DWORD nTimeOut);

I think these are the definitions that should be included:

	BOOL SetFileAttributesA(LPCSTR lpFileName, DWORD dwFileAttributes);
	BOOL SetFileAttributesW(LPCWSTR lpFileName, DWORD dwFileAttributes);

These are my 2 most-used windows.h functions, so it would be great to have them!

I have a M1 machine & it's not possible to build the project ...
I didn't rely on the pre-canned MAKEFILE in test directory (since that simply didn't work at all) & instead, I created a very simple CMakeLists.txt config:

cmake_minimum_required(VERSION 3.10)
project(WindowsHModular)

include_directories(include)

add_library(delta-core STATIC
    # Source files
    test/test.c
    main.c
)

& in the main.c file, I only included the win32/windows.h header.
But the project fails to build running the command cmake --build . with error:

fatal error: too many errors emitted, stopping now [-ferror-limit=]

I'll share a list of the errors. (Most of them, I'm familiar with & know a solution for ... they are simply APIs found only on windows & not on other platforms.)
My entire intention of using WindowsHModular was to build a windows-project which relied on Windows.h header in the code ... So I figured this project would fix the absence of the windows headers ...

Just LoadLibraryExA - https://docs.microsoft.com/en-us/windows/win32/api/libloaderapi/nf-libloaderapi-loadlibraryexa
Might as well add LoadLibraryExW as well - https://docs.microsoft.com/en-us/windows/win32/api/libloaderapi/nf-libloaderapi-loadlibraryexw

No new types needed for these functions.