Compiling Lua Module on x86-64 Windows PC with MSVC

[mkashirin]

Hey! I am trying to call my Rust code from Lua but having some issues. For whatever reason, Lua returns the following error (I'm using Git Bash):

$ lua52 -e "require('target/debug/rustfromlua').hello('Lua')"
C:\Program Files\lua52\lua52.exe: error loading module 'target/debug/rustfromlua' from file '.\target/debug/rustfromlua.dll':
        The specified procedure could not be found.

stack traceback:
        [C]: in ?
        [C]: in function 'require'
        (command line):1: in main chunk
        [C]: in ?

Project Files

This is Cargo.toml:

[package]
name = "rustfromlua"
version = "0.1.0"
edition = "2021"

[lib]
crate-type = ["cdylib"]

[dependencies]
mlua = { version = "0.10.1", features = ["lua52", "module"] }

Here is lib.rs:

use mlua::prelude::*;

fn hello(_: &Lua, name: String) -> LuaResult<()> {
    println!("Hello, {}!", name);
    Ok(())
}

#[mlua::lua_module]
fn rustfromlua(lua: &Lua) -> LuaResult<LuaTable> {
    let exports = lua.create_table()?;
    exports.set("hello", lua.create_function(hello)?)?;
    Ok(exports)
}

I am compiling with just cargo build.

[mkashirin]

@khvzak, can you help, please? I tried to link it properly but is does not see the lua52.lib file giving me the following error:

$ LUA_LIB="/d/Desktop\ Access/Documents/GitHub/rustfromlua/.lua/" LUA_LINK="dylib" cargo build
   Compiling mlua-sys v0.6.5
   Compiling mlua v0.10.1
   Compiling rustfromlua v0.1.0 (D:\Desktop Access\Documents\GitHub\rustfromlua)
error: linking with `link.exe` failed: exit code: 1181
  |
  = note: "C:\\Program Files\\Microsoft Visual Studio\\2022\\Community\\VC\\Tools\\MSVC\\14.40.33807\\bin\\HostX64\\x64\\link.exe"...
  = note: LINK : fatal error LNK1181: cannot open input file 'lua52.lib'

error: could not compile `rustfromlua` (lib) due to 1 previous error

Even though I've downloaded lua-5.2.1_Win64_dll10_lib.zip from here:

$ ls .lua/
include  lua52.dll  lua52.lib

The Lua version I'm trying to compile for is 5.2.1.

[mkashirin]

I successfully resolved the issue by doing exactly what the comment. I assume you cannot call the module if you're not exactly in the CWD with the *.dll file. And for whatever reason the module refused to compile unless I put the Lua library files in the $HOME/Downloads directory. In my opinion this happens due to the linker's inability to see the contents of the disk "D".

[khvzak]

You cannot load module like:

lua52 -e "require('target/debug/rustfromlua').hello('Lua')"

You need to set LUA_CPATH and then load through require("rustfromlua").

[mkashirin]

Thank you for the response.