Humanizr/Humanizer · error · InvalidOperationException

Inflection defines unsupported quantity selector; expected '

Error message

Inflection defines unsupported quantity selector; expected 'exact-numeric-singleton'.

What it means

The inflection surface accepts an optional 'quantitySelector' key, but the only supported value is the literal string 'exact-numeric-singleton'. ParseQuantitySelector throws when the key is present with any other value. The throw is caught during catalog collection and surfaced as an HSG003 diagnostic, which suppresses that locale's generated inflection catalog.

Source

Thrown at src/Humanizer.SourceGenerators/Generators/ProfileCatalogs/InflectionCatalogParsing.cs:162

                    NormalizeGuards(
                        GetOptionalStrings(mapping, "skipSimpleWords", "skip-simple-words"),
                        casing,
                        scripts,
                        "skipSimpleWords"),
                    lexemes,
                    rules));
        }

        static string? ParseQuantitySelector(SimpleYamlMapping mapping)
        {
            if (!mapping.TryGetValue("quantitySelector", out var value))
            {
                return null;
            }

            return value is SimpleYamlScalar { Value: ExactNumericSingletonSelector }
                ? ExactNumericSingletonSelector
                : throw new InvalidOperationException(
                    "Inflection defines unsupported quantity selector; expected 'exact-numeric-singleton'.");
        }

        static void ValidateQuantitySelector(
            SimpleYamlMapping mapping,
            string cardinalRule,
            string? quantitySelector,
            ImmutableArray<InflectionLexemeInput> lexemes,
            ImmutableArray<InflectionRuleInput> rules)
        {
            var hasOptedLexeme = lexemes.Any(static lexeme =>
                lexeme.Display.ContainsKey("one"));
            if (quantitySelector is not null)
            {
                if (!hasOptedLexeme)
                {
                    throw new InvalidOperationException(
                        "Inflection quantitySelector 'exact-numeric-singleton' requires at least one lexeme with an authored 'one' display.");

View on GitHub (pinned to ffc2b77c0f)

Solutions

1. Set the value to exactly 'exact-numeric-singleton'
2. Remove the quantitySelector key entirely if the locale does not need singleton-one selection

Example fix

# before
    quantitySelector: 'nearest-numeric-singleton'
# after
    quantitySelector: 'exact-numeric-singleton'

// In a locale-YAML lint pass, before building:
// 1. Parse surfaces.inflection into a SimpleYamlMapping `m`.
// 2. If m contains 'quantitySelector', its scalar must be exactly:
if (m.TryGetValue("quantitySelector", out var v) &&
    (v is not SimpleYamlScalar s || s.Value != "exact-numeric-singleton"))
{
    Report($"{locale}: quantitySelector must be 'exact-numeric-singleton' or absent.");
}

static bool IsValidQuantitySelector(SimpleYamlMapping m) =>
    !m.TryGetValue("quantitySelector", out var v) ||
    v is SimpleYamlScalar { Value: "exact-numeric-singleton" };

When it happens

Trigger: A locale YAML sets 'quantitySelector:' under 'surfaces.inflection' to anything other than 'exact-numeric-singleton' (e.g. 'nearest-numeric-singleton', a typo, or a scalar with different casing).

Common situations: Authoring a new locale that needs per-number singular/plural behavior and guessing the selector name; copy-paste from an unrelated spec; renaming the key during a refactor without checking the parser's single accepted constant.

Related errors

• Inflection quantitySelector 'exact-numeric-singleton' requir
• Inflection quantitySelector 'exact-numeric-singleton' cannot
• Inflection display category 'one' is unreachable without qua
• Active inflection bundle must define lexemes.
• Inflection lexemes must be mappings.

AI-assisted analysis of Humanizr/Humanizer@ffc2b77c0f (2026-08-13). Data as JSON: /api/errors/86f8953e7eb61729. Report an issue: GitHub.