-- A version number, once published, names one set of bytes forever.

--

-- WHY THIS EXISTS

--

-- Every package in this index is published as an archive of a repository at a

-- tag, so ANY change to that repository changes the artefact. A release

-- therefore needs the version in `mcpp.toml` bumped, and nothing checks that

-- it was: a package's own CI validates the tree in front of it and has no

-- opinion about which numbers are already taken.

--

-- Measured 2026-08-25, following openkal 0.7.0 through the ecosystem: SIX of

-- the eight repositories had a branch ready to merge whose version equalled

-- the version on `main`, which is the version already in this index. Two of

-- them had gained a whole interface implementation. Every one of those

-- packages was green.

--

-- What happens next is quiet rather than loud. `git tag 0.5.3` finds the tag

-- present and succeeds; the archive fetched from that tag is the OLD content;

-- both mirror legs then agree with each other and with the source archive,

-- because all three are the same old bytes. The release verifies perfectly

-- and publishes nothing. The only surviving trace is a second `["0.5.3"]`

-- entry here -- and Lua accepts a repeated key in a table constructor, keeps

-- the last one, and reports nothing.

--

-- THE RULE

--

-- Within one platform section, a version key appears at most once.

--

-- The check is textual and deliberately so. Loading the descriptor is exactly

-- what cannot see this: by the time the table exists, the duplicate has

-- already collapsed into the survivor.

--

-- Usage: lua5.4 tests/check_duplicate_versions.lua <file.lua> [...]

-- Exits non-zero, with ::error lines naming the file, the line, and the

-- platform section the repeat is in.

local failed = false

-- A platform section opens with `<name> = {` at the indentation the

-- descriptors use inside `xpm`, and a version key is `["<digits and dots>"]`.

-- Anything else -- `url`, `sha256`, nested tables -- is passed over.

local function check(path)

local handle = io.open(path, "r")

if not handle then

io.stderr:write(("::error file=%s::cannot be read\n"):format(path))

failed = true

return

end

local section, seen, line_no = nil, {}, 0

for line in handle:lines() do

line_no = line_no + 1

local platform = line:match("^%s%s%s%s%s%s%s%s([%w_]+)%s*=%s*{%s*$")

if platform then

section, seen = platform, {}

end

local version = line:match('^%s*%["([%d][%d%.]*)"%]%s*=')

if version and section then

if seen[version] then

io.stderr:write(("::error file=%s,line=%d::%s appears twice in the %s section (first at line %d). A published version names one set of bytes; bump it instead.\n")

:format(path, line_no, version, section, seen[version]))

failed = true

else

seen[version] = line_no

end

end

end

handle:close()

end

if #arg == 0 then

io.stderr:write("usage: check_duplicate_versions.lua <file.lua> [...]\n")

os.exit(2)

end

for _, path in ipairs(arg) do check(path) end

os.exit(failed and 1 or 0)