A simple Lua module that converts certain (supported) codes to equivalent Win32 console outputs. UTF/wide inputs are not supported. It is installed to `io.write` as an override.

wansi.cpp

/*
 * WANSI - The Windows ANSI Lua Module
 */
 
#ifndef _WIN32
 static_assert(false, "This Lua module is only intended to be built by MSVC tools on Windows.");
#endif

#include <windows.h>
#include <lua.hpp>

BOOL APIENTRY DllMain(HANDLE module, DWORD reason, LPVOID reserved) { return TRUE; }

/***************************************************/

// Some nifty macros
#define ERRORMSG(L, fmt, ...) {\
	LPSTR buf = 0;\
	FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_ALLOCATE_BUFFER, NULL, GetLastError(), 0, (LPSTR)&buf, 0, 0);\
	luaL_error(L, fmt ": %s", __VA_ARGS__, buf);\
	LocalFree(buf);}

#define XNOT(a, b) ~(~(a) | b)
#define STRIPCOL(mods) XNOT(mods, FOREGROUND_RED | FOREGROUND_GREEN | FOREGROUND_BLUE)
#define STRIPCOLB(mods) XNOT(mods, BACKGROUND_RED | BACKGROUND_GREEN | BACKGROUND_BLUE)

// Set up state
static char last = (char) -1;
static bool escaped = false;
static int curCode = -1; 
static WORD modifiers = 0;

/**
 * ANSI code 'visitor' that manages
 *	the current output state given ANSI
 *	escape codes
 */
void handleAnsi(lua_State* L, int value, int section, int character)
{
	// Switch
	switch(value)
	{
	case 30: modifiers = STRIPCOL(modifiers); break;
	case 31: modifiers = STRIPCOL(modifiers) | FOREGROUND_RED; break;
	case 32: modifiers = STRIPCOL(modifiers) | FOREGROUND_GREEN; break;
	case 33: modifiers = STRIPCOL(modifiers) | FOREGROUND_RED | FOREGROUND_GREEN; break;
	case 34: modifiers = STRIPCOL(modifiers) | FOREGROUND_BLUE; break;
	case 35: modifiers = STRIPCOL(modifiers) | FOREGROUND_RED | FOREGROUND_BLUE; break;
	case 36: modifiers = STRIPCOL(modifiers) | FOREGROUND_BLUE | FOREGROUND_GREEN; break;
	case 37: modifiers = STRIPCOL(modifiers) | FOREGROUND_GREEN | FOREGROUND_BLUE | FOREGROUND_RED; break;

	case 40: modifiers = STRIPCOLB(modifiers); break;
	case 41: modifiers = STRIPCOLB(modifiers) | BACKGROUND_RED; break;
	case 42: modifiers = STRIPCOLB(modifiers) | BACKGROUND_GREEN; break;
	case 43: modifiers = STRIPCOLB(modifiers) | BACKGROUND_RED | BACKGROUND_GREEN; break;
	case 44: modifiers = STRIPCOLB(modifiers) | BACKGROUND_BLUE; break;
	case 45: modifiers = STRIPCOLB(modifiers) | BACKGROUND_RED | BACKGROUND_BLUE; break;
	case 46: modifiers = STRIPCOLB(modifiers) | BACKGROUND_BLUE | BACKGROUND_GREEN; break;
	case 47: modifiers = STRIPCOLB(modifiers) | BACKGROUND_GREEN | BACKGROUND_BLUE | BACKGROUND_RED; break;

	case 39:
	case 0: modifiers |= FOREGROUND_GREEN | FOREGROUND_BLUE | FOREGROUND_RED; break;

	case 49: modifiers = STRIPCOLB(modifiers); break;

	case 1: modifiers |= FOREGROUND_INTENSITY; break;
	case 22: modifiers = XNOT(modifiers, FOREGROUND_INTENSITY); break;

	case 4: modifiers |= COMMON_LVB_UNDERSCORE; break;
	case 24: modifiers = XNOT(modifiers, COMMON_LVB_UNDERSCORE); break;

	case 7: modifiers |= COMMON_LVB_REVERSE_VIDEO; break;
	case 27: modifiers = XNOT(modifiers, COMMON_LVB_REVERSE_VIDEO); break;

	default:
		luaL_error(L, "wansi: unsupported ANSI escape code: %d <%d, %d>", (int)value, character, section);
		break;
	}

	// Update attribute
	if(!SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), modifiers))
		ERRORMSG(L, "could not update attributes <%d, %d>", character, section);

	// Reset code
	curCode = -1;
}

/**
 * io.write() replacement function
 */
int wansi_write(lua_State* L)
{
	// Get number of upvalues
	int n = lua_gettop(L);

	// Iterate
	for(int i = 1; i <= n; i++)
	{
		// Get string
		size_t size;
		const char* str = lua_tolstring(L, i, &size);

		// Iterate
		for(int ci = 0; ci < size; ci++)
		{
			// Get char
			char c = str[ci];

			// Escape?
			if(c == '\x1b')
			{
				// Already escaped?
				if(escaped || last == '\x1b')
					luaL_error(L, "invalid ANSI escape sequence; opcode expected, escape character (x1B) discovered <%d, %d>", ci, i);
				goto parseNext;
			}

			// End of escape code?
			else if(c == 'm' && escaped)
			{
				// No code was given? (i.e. \x[1;m which is invalid)
				if(curCode == -1)
					luaL_error(L, "invalid ANSI escape sequence; opcode expected, end-of-sequence ('m') discovered <%d, %d>", ci, i);

				// Visit
				handleAnsi(L, curCode, i, ci);

				// Unflag
				escaped = false;
				goto parseNext;
			}

			// Open bracket?
			else if(c == '[' && last == '\x1b')
			{
				// Flag
				escaped = true;
				goto parseNext;
			}

			// Semi?
			else if(c == ';' && escaped)
			{
				// No code was given? (i.e. \x[;1m which is invalid)
				if(curCode == -1)
					luaL_error(L, "invalid ANSI escape sequence; opcode expected, code separator (';') discovered <%d, %d>", ci, i);

				// Visit
				handleAnsi(L, curCode, i, ci);

				// Continue
				goto parseNext;
			}

			// Number?
			else if(escaped && c >= '0' && c <= '9')
			{
				// Add to it
				if(curCode == -1)
					curCode = 0;
				curCode *= 10;
				curCode += c - '0';
				goto parseNext;
			}

			// Are we escaped and nothing above applies?
			else if(escaped || last == '\x1b')
				// Nope!
				luaL_error(L, "invalid ANSI escape sequence; unexpected character '%c' <%d, %d>", c, ci, i);
			
			// Write
			DWORD out;
			if(!WriteConsoleA(GetStdHandle(STD_OUTPUT_HANDLE), &c, 1, &out, NULL))
				ERRORMSG(L, "I/O error when writing to console <%d, %d>", ci, i);

parseNext:
			// Store last
			last = c;
		}
	}

	// Return STDOut (this mimics the original io.write for stringing)
	lua_getglobal(L, "io");
	lua_getfield(L, -1, "stdout");
	lua_remove(L, -2);
	return 1;
}

/**
 * Entry point for the Lua module
 */
extern "C" __declspec(dllexport) int luaopen_wansi(lua_State* L)
{
	// Get io
	lua_getglobal(L, "io");
	if(lua_isnil(L, -1))
		return luaL_error(L, "global 'io' does not exist; WANSI cannot install");

	// Get write
	lua_getfield(L, -1, "write");
	if(!lua_isfunction(L, -1))
		return luaL_error(L, "'io.write' does not point to a function; WANSI cannot install");

	// Re-assign
	lua_setfield(L, -2, "rawwrite");

	// Push our function
	lua_pushcfunction(L, wansi_write);

	// Install
	lua_setfield(L, -2, "write");

	// Signal WANSI has been installed
	lua_pushboolean(L, 1);
	lua_setfield(L, -2, "wansi");

	// Clean Up
	lua_pop(L, 1);

	// Return true
	lua_pushboolean(L, 1);
	return 1;
}

/***************************************************/

Include with:

-- Through package loader
fn, err = package.load('<PATH_TO_DLL>\\wansi.dll', 'luaopen_wansi')
if not fn or err then error(err or "could not install WANSI; unknown error") end
fn()
assert(io.wansi) -- Optional

-- Through C-loader
package.cpath = package.cpath .. ";<PATH_TO_DLL>\\?.dll"
require "wansi"
assert(io.wansi) -- Optional