Compiler warning regarding ToDictionary method

[vesnx]

I get a compiler warning in MemoryPack.Generator that perhaps needs consideration The class: MemoryPackGenerator.Emitter.cs

The code:

 string EmitConstructor()
    {
        // no need `;` because after using object initializer
        if (this.Constructor == null || this.Constructor.Parameters.Length == 0)
        {
            return $"new {TypeName}()";
        }
        else
        {
            var nameDict = Members.Where(x => x.Symbol != null && x.IsConstructorParameter).ToDictionary(x => x.ConstructorParameterName, x => x.Name, StringComparer.OrdinalIgnoreCase);//--> line 899
            var parameters = this.Constructor.Parameters
                .Select(x =>
                {
                    if (nameDict.TryGetValue(x.Name, out var name))
                    {
                        return $"__{name}";
                    }
                    return null; // invalid, validated.
                })
                .Where(x => x != null);

            return $"new {TypeName}({string.Join(", ", parameters)})";
        }
    }

Severity Code Description Project File Line Suppression State Warning CS8714 The type 'string?' cannot be used as type parameter 'TKey' in the generic type or method 'Enumerable.ToDictionary<TSource, TKey, TElement>(IEnumerable, Func<TSource, TKey>, Func<TSource, TElement>, IEqualityComparer?)'. Nullability of type argument 'string?' doesn't match 'notnull' constraint. MemoryPack.Generator ..\src\MemoryPack.Generator\MemoryPackGenerator.Emitter.cs 899 Active

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[vesnx]

why doesn't MS look at this?

[olivier-spinelli]

Trying to help here:

• MS has nothing to do with this.
• In ... .ToDictionary(x => x.ConstructorParameterName, ..., x.ConstructorParameterName is a nullable string. => To suppresse the warning, ... .ToDictionary(x => x.ConstructorParameterName!, ... (adding the bang! operator) should be enough.

[vesnx]

sure, however it's not my code

[olivier-spinelli]

Of course. You may create a PR for this.

[hadashiA]

Fixed in #232.