util.format: Handle formats expecting an integer in Lua 5.3+ (fixes #1371)

1 files changed, 6 insertions, 0 deletions

diff --git a/util/format.lua b/util/format.lua
index c31f599f..857bb694 100644
--- a/util/format.lua
+++ b/util/format.lua
@@ -7,6 +7,9 @@ local unpack = table.unpack or unpack; -- luacheck: ignore 113/unpack
 local pack = require "util.table".pack; -- TODO table.pack in 5.2+
 local type = type;
 local dump = require "util.serialization".new("debug");
+local num_type = math.type;
+
+local expects_integer = num_type and { c = true, d = true, i = true, o = true, u = true, X = true, x = true, } or {};
 
 local function format(formatstring, ...)
 	local args = pack(...);
@@ -43,6 +46,9 @@ local function format(formatstring, ...)
 			elseif type(arg) ~= "number" then -- arg isn't number as expected?
 				args[i] = tostring(arg);
 				spec = "[%s]";
+			elseif expects_integer[option] and num_type(arg) ~= "integer" then
+				args[i] = tostring(arg);
+				spec = "[%s]";
 			end
 		end
 		return spec;