Config generator doesn't match nullability semantics of built-in Bind

[stephentoub]

The built-in Bind method annotates the object as nullable:

public static void Bind(this IConfiguration configuration, object? instance)

and then explicitly nops if it's null:

if (instance != null)
{
    ...
}

In contrast, the code generated by the generator annotates it as non-nullable and throws an exception if it's null, changing the semantics when using the source generator.

if (obj is null)
{
    throw new ArgumentNullException(nameof(obj));
}

(It also names the parameter obj instead of instance.)

[ghost]

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Issue Details

---

The built-in Bind method annotates the object as nullable:

public static void Bind(this IConfiguration configuration, object? instance)

and then explicitly nops if it's null:

if (instance != null)
{
    ...
}

In contrast, the code generated by the generator annotates it as non-nullable and throws an exception if it's null, changing the semantics when using the source generator.

if (obj is null)
{
    throw new ArgumentNullException(nameof(obj));
}

(It also names the parameter obj instead of instance.)

Author:	stephentoub
Assignees:	-
Labels:	untriaged, area-Extensions-Configuration
Milestone:	-

[layomia]

Consistency is desired cc @tarekgh.

[layomia]

Fixed for 8.0 in #91359.