Inlining doesn't always occur for functions that are used once

[gaymeowing]

Here I have a function for parsing a date included in a git log:

local GIT_DATE_FORMAT = "(%w+) (%w+) (%d+) (%d+):(%d+):(%d+) (%d+) ([?%+%-]%d%d)(%d%d)"
local MONTHS = table.freeze({ 
	Jan = 1, Feb = 2, Mar = 3, Apr = 4, May = 5, Jun = 6, 
	Jul = 7, Aug = 8, Sep = 9, Oct = 10, Nov = 11, Dec = 12
}) :: { [string]: number }

local MATCH = string.match

local function parse_git_date(date: string): number
	-- git log date format: "Day Mon DD HH:MM:SS YYYY +-ZZZZ"
	local _, month, day, hour, minutes, seconds, year, zone_hours, zone_minutes = MATCH(date, GIT_DATE_FORMAT)
	local zone_minutes = tonumber(zone_minutes)
	local zone_hours = tonumber(zone_hours)
	local seconds = tonumber(seconds)
	local minutes = tonumber(minutes)
	local month = MONTHS[month]
	local year = tonumber(year)
	local hour = tonumber(hour)
	local day = tonumber(day)

	if 
		day and month and hour and minutes and seconds and 
		year and zone_hours and zone_minutes
	then
		local timestamp = os.time({
			min = minutes, sec = seconds, month = month, 
			day = day, year = year, hour = hour,
		})

		return timestamp - ((zone_hours * 3600) + (zone_minutes * 60))
	else
		error(`[GIT DATE] could not parse {date} as it wasnt in format "Day Mon DD HH:MM:SS YYYY +-ZZZZ"`)
	end
end

I only use this function once in my code, and it doesn't get inlined as its deemed too expensive even though it should always be inlined because its only used once.