Simulate module() for older wrappers.

Older versions of LuaRocks (e.g. 2.1.0) install script wrappers
that assume that `luarocks.loader` is available in the global
namespace (this is from the module() era). This workaround detects
this (because site_config.lua files written by these old versions
use module(), and therefore create a `luarocks` global.

To reproduce this issue, make a clean install of LuaRocks 2.1.0,
then run `luarocks install luarocks`. Installation succeds,
but running `luarocks` produces `attempt to index field 'loader'
(a nil value)`.

Bug reported by @tomasguisasola.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/luarocks/loader.lua b/src/luarocks/loader.lua
index 26280e94..06a0cfda 100644
--- a/src/luarocks/loader.lua
+++ b/src/luarocks/loader.lua
@@ -22,6 +22,11 @@ local manif_core = require("luarocks.manif_core")
 local deps = require("luarocks.deps")
 local util = require("luarocks.util")
 
+-- Workaround for wrappers produced by older versions of LuaRocks
+if luarocks then
+   luarocks.loader = loader
+end
+
 loader.context = {}
 
 -- Contains a table when rocks trees are loaded,