Getting underlying type of an IEnumerable collection from its ISymbol

Question

I have the ISymbol object for an enumerable collection and need to get the underlying type.

e.g.

List<int> intList;

I have the ISymbol for intList, and need to find the underlying type - in this case, it is int.

I tried using the code listed here, but seems like reflection does not work here.

Here's my code snippet:

private Type GetUnderlyingTypeFromEnumerable(ISymbol symbol)
{  
    Type eType = null;  
    Type[] interfaces = symbol.GetType().GetInterfaces();  
    foreach (Type i in interfaces)  
        if (i.IsGenericType && i.GetGenericTypeDefinition().Equals(typeof(IEnumerable<>)))  
        {  
            eType = i.GetGenericArguments()[0];  
            break;  
        }  

    return eType;  
}

If you have something like: IList collName... you can do - collName.GetType() and find the underlying type — Prateek Shrivastava, Oct 24 '17 at 10:24
Possible duplicate of [getting type T from IEnumerable](https://stackoverflow.com/questions/906499/getting-type-t-from-ienumerablet) — mitaness, Oct 24 '17 at 11:22
@PrateekShrivastava I only have the ISymbol object, not the IList. — user3009098, Oct 24 '17 at 12:09
@VijayanathViswanathan Updated my question with the code sample. — user3009098, Oct 24 '17 at 12:31
`ISymbol` tells you about the code. you will have to look into the documentation. `GetType` is only ever going to return the type of the `ISymbol` itself. Reflection wont help you. Roslyn has already analyzed the code — Daniel A. White, Oct 24 '17 at 12:33
You can't mix Reflection & Roslyn symbols. You need to use the `INamedTypeSymbol` API. — SLaks, Oct 24 '17 at 15:07

score 2 · Answer 1 · answered Oct 25 '17 at 11:12

2

Thanks everyone. I pried around the INamedTypeSymbol interface and found an easy way to solve this:

    private ITypeSymbol GetUnderlyingTypeFromEnumerable(INamedTypeSymbol symbol)
    {
        return symbol.TypeArguments.First();
    }

answered Oct 25 '17 at 11:12

user3009098

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Getting underlying type of an IEnumerable collection from its ISymbol

1 Answers1