util.promise: Switch order of parameters to join()

This saves awkward fiddlery with varargs and also echoes the
signature of pcall/xpcall.

2 files changed, 4 insertions, 6 deletions

diff --git a/spec/util_promise_spec.lua b/spec/util_promise_spec.lua
index f64702bf..307c094a 100644
--- a/spec/util_promise_spec.lua
+++ b/spec/util_promise_spec.lua
@@ -498,10 +498,10 @@ describe("util.promise", function ()
 			local res1, res2;
 			local p1, p2 = promise.new(function (resolve) r1 = resolve end), promise.new(function (resolve) r2 = resolve end);
 
-			local p = promise.join(p1, p2, function (_res1, _res2)
+			local p = promise.join(function (_res1, _res2)
 				res1, res2 = _res1, _res2;
 				return promise.resolve("works");
-			end);
+			end, p1, p2);
 
 			local result;
 			local cb = spy.new(function (v)
diff --git a/util/promise.lua b/util/promise.lua
index 89bd1f26..ea30898c 100644
--- a/util/promise.lua
+++ b/util/promise.lua
@@ -146,12 +146,10 @@ local function all_settled(promises)
 	end);
 end
 
-local function join(...)
+local function join(handler, ...)
 	local promises, n = { ... }, select("#", ...);
-	local handler = promises[n];
-	promises[n] = nil;
 	return all(promises):next(function (results)
-		return handler(unpack(results, 1, n - 1));
+		return handler(unpack(results, 1, n));
 	end);
 end