GSL/GSL.natvis

<?xml version="1.0" encoding="utf-8"?>
<!-- 
    This will make GitHub and some editors recognize this code as XML: 
    vim: syntax=xml
-->
<AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
    <!-- These types are from the util header. -->
    <Type Name="gsl::final_action&lt;*&gt;">
        <DisplayString>{{ invoke = {invoke_}, action = {f_} }}</DisplayString>
        <Expand>
            <Item Name="[invoke]">invoke_</Item>
            <Item Name="[callback]">f_</Item>
        </Expand>
    </Type>

  <!-- These types are from the span header. -->
  <Type Name="gsl::span&lt;*, *&gt;">
        <DisplayString>{{ extent = {storage_.size_} }}</DisplayString>
        <Expand>
            <ArrayItems>
                <Size>storage_.size_</Size>
                <ValuePointer>storage_.data_</ValuePointer>
            </ArrayItems>
        </Expand>
    </Type>

    <!-- These types are from the pointers header. -->
    <Type Name="gsl::not_null&lt;*&gt;">
        <!-- We can always dereference this since it's an invariant. -->
        <DisplayString>value = {*ptr_}</DisplayString>
    </Type>
</AutoVisualizer>