Config generator emits lambdas for error path that force allocation on success path #90971
Description
Consider a method like:
internal class C1
{
public int Value { get; set; }
public static void M(IConfiguration configuration, C1 c) => configuration.Bind(c);
}That results in this BindCore method being emitted:
public static void BindCore(IConfiguration configuration, ref C1 obj, BinderOptions? binderOptions)
{
ValidateConfigurationKeys(typeof(C1), s_configKeys_C1, configuration, binderOptions);
if (configuration["Value"] is string value15)
{
obj.Value = ParseInt(value15, () => configuration.GetSection("Value").Path);
}
}That ParseInt call closes over the configuration parameter, which means the compiler will lift the configuration parameter to a display class and generate code like this:
public static void BindCore(IConfiguration configuration, ref C1 obj, [Nullable(2)] BinderOptions binderOptions)
{
<>c__DisplayClass15_0 <>c__DisplayClass15_ = new <>c__DisplayClass15_0();
<>c__DisplayClass15_.configuration = configuration;
ValidateConfigurationKeys(typeof(C1), s_configKeys_C1, <>c__DisplayClass15_.configuration, binderOptions);
string value22 = <>c__DisplayClass15_.configuration["Value"];
if (value22 != null)
{
obj.Value = ParseInt(value22, new Func<string>(<>c__DisplayClass15_.<BindCore>b__0));
}
}That means we're allocating a <>c__DisplayClass15_0 object on all invocation, even though that lambda causing the closure is only used by ParseInt when parsing fails and an exception is thrown and caught.