Make the workaround for older LuaRocks versions more robust.

1 files changed, 24 insertions, 0 deletions

diff --git a/src/luarocks/loader.lua b/src/luarocks/loader.lua
index 06a0cfda..874bc10c 100644
--- a/src/luarocks/loader.lua
+++ b/src/luarocks/loader.lua
@@ -23,8 +23,25 @@ local deps = require("luarocks.deps")
 local util = require("luarocks.util")
 
 -- Workaround for wrappers produced by older versions of LuaRocks
+local temporary_global = false
 if luarocks then
+   -- The site_config.lua file generated by old versions uses module(),
+   -- so it produces a global `luarocks` table. Since we have the table,
+   -- add the `loader` field to make the old wrappers happy.
    luarocks.loader = loader
+else
+   -- When a new version is installed on top of an old version,
+   -- site_config.lua may be replaced, and then it no longer creates
+   -- a global.
+   -- Detect when being called via -lluarocks.loader; this is
+   -- most likely a wrapper.
+   local info = debug.getinfo(2, "nS")
+   if info.what == "C" and not info.name then
+      luarocks = { loader = loader }
+      temporary_global = true
+      -- For the other half of this hack,
+      -- see the next use of `temporary_global` below.
+   end
 end
 
 loader.context = {}
@@ -60,6 +77,13 @@ function loader.add_context(name, version)
    -- assert(type(name) == "string")
    -- assert(type(version) == "string")
 
+   if temporary_global then
+      -- The first thing a wrapper does is to call add_context.
+      -- From here on, it's safe to clean the global environment.
+      luarocks = nil
+      temporary_global = false
+   end
+
    if loader.context[name] then
       return
    end