[clang] SSAF JSON Format (PR #180021)

[Aviral Goel via cfe-commits]

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@@ -29,6 +29,7 @@ class EntityIdTable;
 /// \see EntityIdTable
 class EntityId {
   friend class EntityIdTable;
+  friend class SerializationFormat;
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aviralg wrote:

For serializing and deserializing EntityId objects.

https://github.com/llvm/llvm-project/pull/180021