config file: do not assume 'variable' table exists (for compat with LR2)

This change results in a default config that works in both LuaRocks 2 and 3.
We do not promise a compatible configuration format, but it's nice to avoid
unnecessary breakage if we can.

2 files changed, 10 insertions, 7 deletions

diff --git a/configure b/configure
index ecdb649a..0fbee6f6 100755
--- a/configure
+++ b/configure
@@ -485,10 +485,12 @@ EOF
    echo '   { name = "system", root = "'"$ROCKS_TREE"'" },'
    echo '}'
    if [ -n "$LUA_INTERPRETER" ]; then echo 'lua_interpreter = "'"$LUA_INTERPRETER"'"' ; fi
-   if [ -n "$LUA_DIR" ]; then echo 'variables.LUA_DIR = "'"$LUA_DIR"'"' ; fi
-   if [ -n "$LUA_INCDIR" ]; then echo 'variables.LUA_INCDIR = "'"$LUA_INCDIR"'"' ; fi
-   if [ -n "$LUA_BINDIR" ]; then echo 'variables.LUA_BINDIR = "'"$LUA_BINDIR"'"' ; fi
-   if [ -n "$LUA_LIBDIR" ]; then echo 'variables.LUA_LIBDIR = "'"$LUA_LIBDIR"'"' ; fi
+   echo 'variables = {'
+   if [ -n "$LUA_DIR" ]; then echo '   LUA_DIR = "'"$LUA_DIR"'",' ; fi
+   if [ -n "$LUA_INCDIR" ]; then echo '   LUA_INCDIR = "'"$LUA_INCDIR"'",' ; fi
+   if [ -n "$LUA_BINDIR" ]; then echo '   LUA_BINDIR = "'"$LUA_BINDIR"'",' ; fi
+   if [ -n "$LUA_LIBDIR" ]; then echo '   LUA_LIBDIR = "'"$LUA_LIBDIR"'",' ; fi
+   echo '}'
 } > "config-$LUA_VERSION.lua.in"
 
 echo
diff --git a/src/luarocks/core/cfg.lua b/src/luarocks/core/cfg.lua
index af57e7ca..b8fedd28 100644
--- a/src/luarocks/core/cfg.lua
+++ b/src/luarocks/core/cfg.lua
@@ -657,9 +657,10 @@ function cfg.init(lua_data, project_dir, warning)
    cfg.lua_version = lua_data.lua_version or cfg.lua_version
    cfg.luajit_version = lua_data.luajit_version or cfg.luajit_version
    cfg.lua_interpreter = lua_data.lua_interpreter or cfg.lua_interpreter
-   cfg.variables.LUA_BINDIR = lua_data.lua_bindir or cfg.variables.LUA_BINDIR
-   cfg.variables.LUA_INCDIR = lua_data.lua_incdir or cfg.variables.LUA_INCDIR
-   cfg.variables.LUA_LIBDIR = lua_data.lua_libdir or cfg.variables.LUA_LIBDIR
+   cfg.variables.LUA_BINDIR = lua_data.lua_bindir or cfg.variables.LUA_BINDIR or lua_bindir
+   cfg.variables.LUA_INCDIR = lua_data.lua_incdir or cfg.variables.LUA_INCDIR or lua_incdir
+   cfg.variables.LUA_LIBDIR = lua_data.lua_libdir or cfg.variables.LUA_LIBDIR or lua_libdir
+   cfg.variables.LUA_DIR = lua_data.lua_dir or cfg.variables.LUA_DIR or lua_dir
 
    -- Build a default list of rocks trees if not given
    if not next(cfg.rocks_trees) then