cilium/cilium · info

expected Value as CallExpr

Error message

expected Value as CallExpr

What it means

The KeyValueExpr's value is not a function call (*ast.CallExpr). The analyzer only tracks initializer fields whose value directly calls a *Vec constructor, so non-call values (literals, identifiers, selector expressions) are rejected with this sentinel and skipped.

Source

Thrown at tools/metricslint/pkg/analyzer/analyzer.go:115

		return 0, fmt.Errorf("unsupported nested varlen array: %w", err)
	}
	return len(nestedSlice.Elts), nil
}

func filterRelevantConstructors(node ast.Node) (object, constructor string, argCount int, err error) {
	// Look for an initializer with key-value expressions that call another
	// function to initialize the field.
	kv, ok := node.(*ast.KeyValueExpr)
	if !ok {
		return "", "", 0, fmt.Errorf("expected KeyValueExpr")
	}
	key, ok := kv.Key.(*ast.Ident)
	if !ok {
		return "", "", 0, fmt.Errorf("expected Key as Ident")
	}
	call, ok := kv.Value.(*ast.CallExpr)
	if !ok {
		return "", "", 0, fmt.Errorf("expected Value as CallExpr")
	}

	// Look for a function with at least two args, where the last arg is a
	// composite literal (such as a slice). Example:
	//
	//     metric.NewCounterVec(opts, []string{...})
	if len(call.Args) < 2 {
		return "", "", 0, fmt.Errorf("expected 2+ arguments to constructor")
	}
	lastArg, ok := call.Args[len(call.Args)-1].(*ast.CompositeLit)
	if !ok {
		return "", "", 0, fmt.Errorf("expected last arg as CompositeLit")
	}

	// Store the object and the initializer function. Assume there's just
	// one which has a composite literal as the last parameter.
	object = key.Name
	argCount = len(lastArg.Elts)

View on GitHub (pinned to ac7b90affa)

Solutions

1. No action needed — this is an expected skip for non-constructor initializers
2. If the field is a metric, call the Vec constructor inline in the initializer rather than assigning a pre-built variable

Example fix

// before
var c = metric.NewCounterVec(opts, labels)
s := structA{counter: c}
// after
s := structA{counter: metric.NewCounterVec(opts, labels)}

call, ok := kv.Value.(*ast.CallExpr)
if !ok {
    return // value is not a constructor call; skipped
}

When it happens

Trigger: Struct fields initialized with plain values: counter: someVar, counter: pkg.PreexistingCounter, or counter: &struct{}{...} inside a composite literal scanned by metricslint.

Common situations: Assigning pre-built metrics from other packages or variables; initializing non-metric fields of the same struct; wrapping constructors in helper closures.

Related errors

• unknown identifier
• expected assignment statement
• unexpected RHS expression length
• expected composite literal
• unsupported ellipsis expression

AI-assisted analysis of cilium/cilium@ac7b90affa (2026-08-31). Data as JSON: /api/errors/05a4e4ee3daa1ada. Report an issue: GitHub.