state-holding fix: track unique identifiers for Func's in CompHash's, not Func's themselves

src/CompHash.cc

@@ -260,13 +260,16 @@ bool CompositeHash::RecoverOneVal(const HashKey& hk, Type* t, ValPtr* pval, bool
 					{
 					uint32_t id;
 					hk.Read("func", id);
-					const auto& f = Func::GetFuncPtrByID(id);
 
-					if ( ! f )
+					ASSERT(func_id_to_func != nullptr);
+
+					if ( id >= func_id_to_func->size() )
 						reporter->InternalError("failed to look up unique function id %" PRIu32
 						                        " in CompositeHash::RecoverOneVal()",
 						                        id);
 
+					const auto& f = func_id_to_func->at(id);
+
 					*pval = make_intrusive<FuncVal>(f);
 					const auto& pvt = (*pval)->GetType();
 
@@ -547,7 +550,31 @@ bool CompositeHash::SingleValHash(HashKey& hk, const Val* v, Type* bt, bool type
 			switch ( v->GetType()->Tag() )
 				{
 				case TYPE_FUNC:
-					hk.Write("func", v->AsFunc()->GetUniqueFuncID());
+					{
+					auto f = v->AsFunc();
+
+					if ( ! func_to_func_id )
+						const_cast<CompositeHash*>(this)->BuildFuncMappings();
+
+					auto id_mapping = func_to_func_id->find(f);
+					uint32_t id;
+
+					if ( id_mapping == func_to_func_id->end() )
+						{
+						// We need the pointer to stick around
+						// for our lifetime, so we have to get
+						// a non-const version we can ref.
+						FuncPtr fptr = {NewRef{}, const_cast<Func*>(f)};
+
+						id = func_id_to_func->size();
+						func_id_to_func->push_back(std::move(fptr));
+						func_to_func_id->insert_or_assign(f, id);
+						}
+					else
+						id = id_mapping->second;
+
+					hk.Write("func", id);
+					}
 					break;
 
 				case TYPE_PATTERN:

src/CompHash.h

@@ -4,7 +4,7 @@
 
 #include <memory>
 
-#include "zeek/IntrusivePtr.h"
+#include "zeek/Func.h"
 #include "zeek/Type.h"
 
 namespace zeek
@@ -61,6 +61,18 @@ protected:
 
 	bool EnsureTypeReserve(HashKey& hk, const Val* v, Type* bt, bool type_check) const;
 
+	// The following are for allowing hashing of function values.
+	// These can occur, for example, in sets of predicates that get
+	// iterated over.  We use pointers in order to keep storage
+	// lower for the common case of these not being needed.
+	std::unique_ptr<std::unordered_map<const Func*, uint32_t>> func_to_func_id;
+	std::unique_ptr<std::vector<FuncPtr>> func_id_to_func;
+	void BuildFuncMappings()
+		{
+		func_to_func_id = std::make_unique<std::unordered_map<const Func*, uint32_t>>();
+		func_id_to_func = std::make_unique<std::vector<FuncPtr>>();
+		}
+
 	TypeListPtr type;
 	bool is_singleton = false; // if just one type in index
 	};

src/Func.cc

@@ -133,20 +133,6 @@ std::string render_call_stack()
 	return rval;
 	}
 
-Func::Func()
-	{
-	unique_id = unique_ids.size();
-	unique_ids.push_back({NewRef{}, this});
-	}
-
-Func::Func(Kind arg_kind) : kind(arg_kind)
-	{
-	unique_id = unique_ids.size();
-	unique_ids.push_back({NewRef{}, this});
-	}
-
-Func::~Func() = default;
-
 void Func::AddBody(detail::StmtPtr /* new_body */,
                    const std::vector<detail::IDPtr>& /* new_inits */, size_t /* new_frame_size */,
                    int /* priority */)
@@ -238,7 +224,6 @@ void Func::CopyStateInto(Func* other) const
 	other->type = type;
 
 	other->name = name;
-	other->unique_id = unique_id;
 	}
 
 void Func::CheckPluginResult(bool handled, const ValPtr& hook_result, FunctionFlavor flavor) const

src/Func.h

@@ -61,9 +61,7 @@ public:
 		BUILTIN_FUNC
 		};
 
-	explicit Func(Kind arg_kind);
-
-	~Func() override;
+	explicit Func(Kind arg_kind) : kind(arg_kind) { }
 
 	virtual bool IsPure() const = 0;
 	FunctionFlavor Flavor() const { return GetType()->Flavor(); }
@@ -122,14 +120,8 @@ public:
 
 	virtual detail::TraversalCode Traverse(detail::TraversalCallback* cb) const;
 
-	uint32_t GetUniqueFuncID() const { return unique_id; }
-	static const FuncPtr& GetFuncPtrByID(uint32_t id)
-		{
-		return id >= unique_ids.size() ? Func::nil : unique_ids[id];
-		}
-
 protected:
-	Func();
+	Func() = default;
 
 	// Copies this function's state into other.
 	void CopyStateInto(Func* other) const;
@@ -140,10 +132,8 @@ protected:
 	std::vector<Body> bodies;
 	detail::ScopePtr scope;
 	Kind kind = SCRIPT_FUNC;
-	uint32_t unique_id = 0;
 	FuncTypePtr type;
 	std::string name;
-	static inline std::vector<FuncPtr> unique_ids;
 	};
 
 namespace detail