rockspec: re-add deprecated function type().

Removing this broke the behavior of some luarocks.build
plugins. LuaRocks does not have a stable public API,
but since this function was returned as part of the
function signature, we'll revert this as a deprecated
function, to be removed in LuaRocks 4.0.

Closes #1800.

2 files changed, 30 insertions, 2 deletions

diff --git a/src/luarocks/rockspecs.lua b/src/luarocks/rockspecs.lua
index 8a1a528e..7f137b87 100644
--- a/src/luarocks/rockspecs.lua
+++ b/src/luarocks/rockspecs.lua
@@ -24,6 +24,19 @@ local vendored_build_type_set = {
    ["none"] = true,
 }
 
+local rockspec_mt_funcs = {}
+
+local rockspec_mt = {}
+rockspec_mt.__index = rockspec_mt_funcs
+
+function rockspec_mt_funcs.type()
+   util.warning("The function rockspec.type() is no longer " ..
+   "necessary and is now deprecated. Please update your " ..
+   "plugin to remove calls to this function.")
+
+   return "rockspec"
+end
+
 
 
 
@@ -181,7 +194,8 @@ function rockspecs.from_persisted_table(filename, rockspec, globals, quick)
       configure_paths(rockspec)
    end
 
-   return rockspec
+
+   return setmetatable(rockspec, rockspec_mt)
 end
 
 return rockspecs
diff --git a/src/luarocks/rockspecs.tl b/src/luarocks/rockspecs.tl
index 9f12649c..7f31f786 100644
--- a/src/luarocks/rockspecs.tl
+++ b/src/luarocks/rockspecs.tl
@@ -24,6 +24,19 @@ local vendored_build_type_set: {string: boolean} = {
    ["none"] = true,
 }
 
+local rockspec_mt_funcs = {}
+
+local rockspec_mt: metatable<Rockspec> = {}
+rockspec_mt.__index = rockspec_mt_funcs
+
+function rockspec_mt_funcs.type(): string
+   util.warning("The function rockspec.type() is no longer " ..
+      "necessary and is now deprecated. Please update your " ..
+      "plugin to remove calls to this function.")
+
+   return "rockspec"
+end
+
 --- Perform platform-specific overrides on a table.
 -- Overrides values of table with the contents of the appropriate
 -- subset of its "platforms" field. The "platforms" field should
@@ -181,7 +194,8 @@ function rockspecs.from_persisted_table(filename: string, rockspec: Rockspec, gl
       configure_paths(rockspec)
    end
 
-   return rockspec
+   -- TODO remove this on LuaRocks 4.0
+   return setmetatable(rockspec, rockspec_mt)
 end
 
 return rockspecs