[clang] WIP [clang][ssaf] Add TUSummaryBuilder and testing features (PR #180779)

[Jan Korous via cfe-commits]

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@@ -40,6 +44,8 @@ class EntityId {
   bool operator==(const EntityId &Other) const { return Index == Other.Index; }
   bool operator<(const EntityId &Other) const { return Index < Other.Index; }
   bool operator!=(const EntityId &Other) const { return !(*this == Other); }
+
+  friend llvm::raw_ostream &operator<<(llvm::raw_ostream &, const EntityId &);
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jkorous-apple wrote:

The commit message says it's for debugging. What scenario do we have in mind? FWIW classes used in AST implement `dump` method.

https://github.com/llvm/llvm-project/pull/180779