Update metadata when entities are deleted by an EnC edit

[tmat]

Roslyn now allows to delete type members. Deleted method bodies are updated to throw MissingMethodException or to call to the new method (WIP). The deletions are however not reflected in metadata returned by Reflection which may affect app frameworks that depend on Reflection information.

Consider adding a naming convention for names of deleted members that Roslyn can use to mark deleted members and that Reflection skips over when enumerating type members.

[ghost]

Tagging subscribers to this area: @dotnet/area-system-reflection
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Issue Details

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Roslyn now allows to delete type members. Deleted method bodies are updated to throw MissingMethodException or to call to the new method (WIP). The deletions are however not reflected in metadata returned by Reflection which may affect Frameworks that depend on Reflection information.

Consider adding a naming convention for names of deleted members that Roslyn can use to mark deleted members and that Reflection skips over when enumerating type members.

Author:	tmat
Assignees:	-
Labels:	area-System.Reflection
Milestone:	-

[tmat]

@lambdageek
@tommcdon (FYI: I added area-EnC-CLR label)
@davidwengier

[tommcdon]

cc @mikelle-rogers

[lambdageek]

Mono has had this code since time immemorial (but only for fields, not methods, properties, events, etc):

/* a field is ignored if it's named "_Deleted" and it has the specialname and rtspecialname flags set */
#define mono_field_is_deleted(field) (((field)->type->attrs & (FIELD_ATTRIBUTE_SPECIAL_NAME | FIELD_ATTRIBUTE_RT_SPECIAL_NAME)) \
				      && (strcmp (mono_field_get_name (field), "_Deleted") == 0))

Perhaps we could formalize something like this? (on the other hand, this affects more than reflection in Mono, it's also used in the instance layout calculation, for example)

In any case, the ECMA "special name" attribute flags on members might be useful

[teo-tsirpanis]

Can you rename the label to area-EnC-coreclr to match with the others' naming style (and I will keep only this because issues have only one area)? docs/area-owners.md needs to be updated as well.

[ghost]

Tagging subscribers to this area: @tommcdon
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Roslyn now allows to delete type members. Deleted method bodies are updated to throw MissingMethodException or to call to the new method (WIP). The deletions are however not reflected in metadata returned by Reflection which may affect app frameworks that depend on Reflection information.

Consider adding a naming convention for names of deleted members that Roslyn can use to mark deleted members and that Reflection skips over when enumerating type members.

Author:	tmat
Assignees:	mikelle-rogers
Labels:	area-Diagnostics-coreclr, feature-request, area-EnC-mono
Milestone:	8.0.0

[jeffschwMSFT]

I deleted area-enc-clr and added the area label area-diagnostics-coreclr

[GSPP]

Throwing MissingMethodException seems dubious because this exception usually means a mismatch between binaries from different compilations/versions. This is going to be misleading.