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diff util/multitable.lua @ 14140:c9c4a13732e4 13.0

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util.multitable: Don't treat false as a missing key 'if not next(some_table)' is a tempting pattern to check whether a table is empty, but we have had multiple bugs in the past where a literal `false` was present as a key, incorrectly matching this test. The correct test is to test for nil, which cannot ever be a key, and means the table is legitimately empty.
author Matthew Wild <mwild1@gmail.com>
date Fri, 17 Apr 2026 17:45:31 +0100
parents 39ae08180c81
children
line wrap: on
line diff
--- a/util/multitable.lua	Fri Apr 17 17:39:06 2026 +0100
+++ b/util/multitable.lua	Fri Apr 17 17:45:31 2026 +0100
@@ -58,14 +58,14 @@
 		local v = t[k];
 		if v then
 			r(v, n+1, _end, ...);
-			if not next(v) then
+			if next(v) == nil then
 				t[k] = nil;
 			end
 		end
 	else
 		for _,b in pairs(t) do
 			r(b, n+1, _end, ...);
-			if not next(b) then
+			if next(b) == nil then
 				t[_] = nil;
 			end
 		end