luafilesystem (lfs) cannot be uninstalled under Windows (msys2/mingw)

[osch]

• Platform:

  • Windows (msys2/mingw)

• LuaRocks version:

  • 3.9.0

• Configuration file:

  rocks_trees = {
     { name = "user", root = home .. "/.luarocks" };
     { name = "system", root = "C:/msys64/mingw64" };
  }
  lua_interpreter = "lua.exe";
  variables = {
     LUA_DIR = "C:/msys64/mingw64";
     LUA_BINDIR = "C:/msys64/mingw64/bin";
  }

• Description:

  Luarocks cannot remove lfs.dll because it is used by luarocks itself and Windows does not allow to remove
  the file while it is open.

  This issue also raises the questions if it's a good idea that Luarocks uses lfs if luafilesystem is installed. This has also the implication of increased complexity because there are two implementations within Luarocks for handling files: one builtin and another one using lfs. This also could hide errors if the fallback implementation is not tested because lfs is arround, see for example Luarocks: use cmd mkdir msys2/MINGW-packages#12002

  Steps to reproduce:

  1. assure that lfs is not installed:

     $  luarocks show luafilesystem
     Error: cannot find package luafilesystem
     Use 'list' to find installed rocks.
     $  lua -e 'print(require"lfs")'
     C:\msys64\mingw64\bin\lua.exe: (command line):1: module 'lfs' not found:
     

  2. install lfs:

     $  luarocks install luafilesystem
     ...
     

  3. check that lfs is installed:

     $  luarocks show luafilesystem
     LuaFileSystem 1.8.0-1 - File System Library for the Lua Programming Language
     ...
     $  lua -e 'print(require"lfs")'
     table: 000001ade2579ef0 C:\msys64\mingw64\bin\..\lib\lua\5.4\lfs.dll
     

  4. remove lfs:

     $  luarocks remove luafilesystem
     Checking stability of dependencies in the absence of
     luafilesystem 1.8.0-1...
     
     Removing luafilesystem 1.8.0-1...
     Removal successful.
     

  5. now luarocks assumes that lfs is uninstalled, however it is still there:

     $  luarocks show luafilesystem
     Error: cannot find package luafilesystem
     Use 'list' to find installed rocks.
     $  lua -e 'print(require"lfs")'
     table: 0000025ce0519eb0 C:\msys64\mingw64\bin\..\lib\lua\5.4\lfs.dll
     

  6. re-installing lfs:

     $  luarocks install luafilesystem
     Installing https://luarocks.org/luafilesystem-1.8.0-1.src.rock
     luafilesystem 1.8.0-1 depends on lua >= 5.1 (5.4-1 provided by VM)
     gcc -O2 -fPIC -c -o src/lfs.o -IC:/msys64/mingw64/include src/lfs.c
     gcc  -shared -o lfs.dll src/lfs.o C:/msys64/mingw64/bin/lua54.dll -lm
     luafilesystem 1.8.0-1 is now installed in C:/msys64/mingw64 (license: MIT/X11)
     Warning: C:/msys64/mingw64/lib/lua/5.4/lfs.dll is not tracked by this installation of LuaRocks. Moving it to C:/msys64/mingw64/lib/lua/5.4/lfs.dll~