apache/beam · warning

Invalid dictionary call

Error message

Invalid dictionary call

What it means

The specialize tool's dict helper builds a map[string]any from alternating key/value arguments. If an odd number of arguments is passed — meaning some key has no value — it panics with 'Invalid dictionary call'.

Solutions

1. Ensure dict() is only ever called with an even number of arguments (key, value pairs)
2. Check each dict(...) call site in main.go and count its arguments
3. Add a compile-time constant or struct for template params instead of variadic pairs to avoid recurrence

Example fix

// before
dict("namespace", ns, "params")
// after
dict("namespace", ns, "params", params)

if len(args)%2 != 0 {
	return errors.New("dict requires key/value pairs")
}

// in the specialize tool
if len(values)%2 != 0 {
	return fmt.Errorf("dict called with odd arg count at %s", callerSite)
}

When it happens

Trigger: Calling dict() inside the specialize tool's template data construction with an odd number of arguments, e.g. dict("key1", v1, "key2") with a missing value.

Common situations: Editing the specialize tool's generated-code parameters and dropping one of a key/value pair; adding a template variable without its value.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• AfterProcessingTime trigger set without a delay or…
• At least one subtrigger required for composite triggers.
• attempted to add namespace to missing coder id
• attempted to add namespace to missing windowing strategy id
• batch: failed to marshal worker UUID

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/9836c5b19e8f7dd0. Report an issue: GitHub.

Appendix: source

Thrown at sdks/go/cmd/specialize/main.go:262

	var ret []int
	for k := 0; k < i; k++ {
		ret = append(ret, k)
	}
	return ret
}

func add(i int, j int) int {
	return i + j
}

func mult(i int, j int) int {
	return i * j
}

func dict(values ...any) map[string]any {
	dict := make(map[string]any, len(values)/2)
	if len(values)%2 != 0 {
		panic("Invalid dictionary call")
	}
	for i := 0; i < len(values); i += 2 {
		dict[values[i].(string)] = values[i+1]
	}

	return dict
}

func list(values ...string) []string {
	return values
}

func genericTypingRepresentation(in int, out int, includeType bool) string {
	seenElements := false
	typing := ""
	if in > 0 {
		typing += fmt.Sprintf("[I%v", 0)
		for i := 1; i < in; i++ {

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