sample.cs

        private static ITypeSymbol GetRangeVariableType(SemanticModel semanticModel, IRangeVariableSymbol symbol)
        {
            ITypeSymbol type = null;

            if (!symbol.Locations.IsEmpty)
            {
                var location = symbol.Locations.First();
                if (location.IsInSource && location.SourceTree == semanticModel.SyntaxTree)
                {
                    var token = location.SourceTree.GetRoot().FindToken(symbol.Locations.First().SourceSpan.Start);
                    var queryBody = GetQueryBody(token);
                    if (queryBody != null)
                    {
                        // To heuristically determine the type of the range variable in a query
                        // clause, we speculatively bind the name of the variable in the select
                        // or group clause of the query body.
                        var identifierName = SyntaxFactory.IdentifierName(symbol.Name);
                        type = semanticModel.GetSpeculativeTypeInfo(
                            queryBody.SelectOrGroup.Span.End - 1, identifierName, SpeculativeBindingOption.BindAsExpression).Type;
                    }

                    var identifier = token.Parent as IdentifierNameSyntax;
                    if (identifier != null)
                    {
                        type = semanticModel.GetTypeInfo(identifier).Type;
                    }
                }
            }

            return type;
        }