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// For compile-time compat, the following rules should work for producing a reference assembly. We drop all private fields, |
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// but add back certain synthesized private fields for a value type (struct) as follows: |
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// 1. If there is a ref field or reference type field in the struct or within the fields' type closure, |
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// it should emit a reference type and a value type dummy field. |
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// - The reference type dummy field is needed in order to inform the compiler to block |
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// taking pointers to this struct because the GC will not track updating those references. |
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// - The value type dummy field is needed in order for the compiler to error correctly on definite assignment checks in all scenarios. dotnet/roslyn#30194 |
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// 2. If there are no reference type fields, but there are value type fields in the struct field closure, |
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// and at least one of these fields is a nonempty struct, then we should emit a value type dummy field. |
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// - The previous rules are for definite assignment checks, so the compiler knows there is a private field |
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// that has not been initialized to error about uninitialized structs. |
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// |
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// 3. If the type is generic, then for every type parameter of the type, if there are any private |
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// or internal fields that are or contain any members whose type is that type parameter, |
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// we add a direct private field of that type. |
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// - Compiler needs to see all fields that have generic arguments (even private ones) to be able |
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// to validate there aren't any struct layout cycles. |
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// Note: By "private", we mean not visible outside the assembly. |
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// For more details see issue https://github.com/dotnet/corefx/issues/6185 |
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// this blog is helpful as well http://blog.paranoidcoding.com/2016/02/15/are-private-members-api-surface.html |