MinGW undefined reference libcurl-CodePudding

So i have written an app in c to download mp3s from the web using a list. It uses libcurl to download them.

I am on linux. Compiling with

 g   main.cpp -lcurl -o word2mp3

works fine. I need an windows executable, but running x86_64-w64-mingw32-g main.cpp -o wordtest returns the

undefined reference to `__imp_curl_easy_init'

followed by the other curl functions. Adding -lcurl to the command also gives an error saying that curl isn't found.

I've tried and searched everywhere, no luck, I'm a beginner.

Link to my github repo: https://github.com/sharpclone/Word2Mp3

CodePudding user response：

You need to compile libcurl with MinGW, or find a precompiled one. The one you installed to compile your app on Linux was compiled with a Linux compiler, and wouldn't work with MinGW.

MSYS2 repos have a bunch of precompiled libraries for different flavors of MinGW.

I've made a script to automatically download those libraries, since their package manager only works on Windows.

git clone https://github.com/holyblackcat/quasi-msys2
cd quasi-msys2
make install _gcc _curl
env/shell.sh

cd ..
git clone https://github.com/sharpclone/Word2Mp3
cd Word2Mp3/
win-clang   main.cpp -lcurl -o word2mp3

This doesn't rely on an external MinGW installation, and only requires Clang (and LLD) to be installed (a regular Clang for Linux, unlike GCC you don't need to install a special version of it to cross-compile).

Or, if you prefer your existing compiler, you can stop at make install _curl, then manually specify the path to the installed library, normally -Lquasi-msys2/root/mingw64/lib. You just need to make sure the MSYS2 repo you're using matches your compiler.

CodePudding user response：

To fix the undefined reference warning, you need to link to the required library, so the -lcurl is correct and required.

If the compiler cannot find the library, you need to tell him where to find it, that can be done by passing -L followed by the path to the library (that would be the path to the directory where libcurl.dll.a is in).

The order of the parameters can also be relevant, I think the correct order would be -L <path> -lcurl.