diff --git a/CHANGES b/CHANGES
index efaa51f596..89cc1d1c22 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,4 +1,22 @@
 
+4.1.0-dev.355 | 2021-03-23 19:05:10 -0700
+
+  * add option for deterministic descriptions of sets & tables (Vern Paxson, Corelight)
+
+  * determinism for concurrent Zeek test suite invocations; split out deprecations (Vern Paxson, Corelight)
+
+  * disambiguate descriptions of enum types; include attributes when describing record types (Vern Paxson, Corelight)
+
+  * more liberal view of attribute equality; allow suppressing attr type-checking (Vern Paxson, Corelight)
+
+  * support for operations on sets that return new values (Vern Paxson, Corelight)
+
+  * add low-level method for adding new enum values (Vern Paxson, Corelight)
+
+  * sundry accessors/cast-ers; RE_Matcher's track their construction values (Vern Paxson, Corelight)
+
+  * add convenience functions for comparing IP addresses (Vern Paxson, Corelight)
+
 4.1.0-dev.346 | 2021-03-23 17:25:02 -0700
 
   * Add new ``./configure --plugindir`` option (Vlad Grigorescu)
diff --git a/VERSION b/VERSION
index 5775bc751e..d1342ec5fb 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.1.0-dev.346
+4.1.0-dev.355
diff --git a/src/Attr.cc b/src/Attr.cc
index 6850c80b5f..976fde083e 100644
--- a/src/Attr.cc
+++ b/src/Attr.cc
@@ -208,8 +208,11 @@ void Attributes::AddAttr(AttrPtr attr, bool is_redef)
 	attrs.emplace_back(attr);
 
 	// We only check the attribute after we've added it, to facilitate
-	// generating error messages via Attributes::Describe.
-	CheckAttr(attr.get());
+	// generating error messages via Attributes::Describe.  If the
+	// instantiator of the object specified a null type, however, then
+	// that's a signal to skip the checking.
+	if ( type )
+		CheckAttr(attr.get());
 
 	// For ADD_FUNC or DEL_FUNC, add in an implicit REDEF, since
 	// those attributes only have meaning for a redefinable value.
diff --git a/src/Attr.h b/src/Attr.h
index 5f1f2ab59f..9c29c4ccd0 100644
--- a/src/Attr.h
+++ b/src/Attr.h
@@ -86,10 +86,11 @@ public:
 			return false;
 
 		if ( expr || other.expr )
-			// If any has an expression and they aren't the same object, we
-			// declare them unequal, as we can't really find out if the two
-			// expressions are equivalent.
-			return (expr == other.expr);
+			// Too hard to check for equivalency, since one
+			// might be expressed/compiled differently than
+			// the other, so assume they're compatible, as
+			// long as both are present.
+			return expr && other.expr;
 
 		return true;
 		}
diff --git a/src/Desc.cc b/src/Desc.cc
index 3497f73680..0def8cd8aa 100644
--- a/src/Desc.cc
+++ b/src/Desc.cc
@@ -40,6 +40,7 @@ ODesc::ODesc(DescType t, File* arg_f)
 	indent_level = 0;
 	is_short = false;
 	want_quotes = false;
+	want_determinism = false;
 	do_flush = true;
 	include_stats = false;
 	indent_with_spaces = 0;
diff --git a/src/Desc.h b/src/Desc.h
index 54900329ec..23fb172ec6 100644
--- a/src/Desc.h
+++ b/src/Desc.h
@@ -47,6 +47,11 @@ public:
 	bool WantQuotes() const	{ return want_quotes; }
 	void SetQuotes(bool q)	{ want_quotes = q; }
 
+	// Whether to ensure deterministic output (for example, when
+	// describing TableVal's).
+	bool WantDeterminism() const	{ return want_determinism; }
+	void SetDeterminism(bool d)	{ want_determinism = d; }
+
 	// Whether we want to print statistics like access time and execution
 	// count where available.
 	bool IncludeStats() const	{ return include_stats; }
@@ -194,6 +199,7 @@ protected:
 	bool escape;	// escape unprintable characters in output?
 	bool is_short;
 	bool want_quotes;
+	bool want_determinism;
 
 	int indent_with_spaces;
 
diff --git a/src/Expr.h b/src/Expr.h
index d0560942e1..ae275a7a84 100644
--- a/src/Expr.h
+++ b/src/Expr.h
@@ -96,6 +96,7 @@ class IndexAssignExpr;
 class IndexExpr;
 class IsExpr;
 class InlineExpr;
+class LambdaExpr;
 class ListExpr;
 class NameExpr;
 class RefExpr;
@@ -216,6 +217,7 @@ public:
 	ZEEK_EXPR_ACCESSOR_DECLS(IndexExpr)
 	ZEEK_EXPR_ACCESSOR_DECLS(IsExpr)
 	ZEEK_EXPR_ACCESSOR_DECLS(InlineExpr)
+	ZEEK_EXPR_ACCESSOR_DECLS(LambdaExpr)
 	ZEEK_EXPR_ACCESSOR_DECLS(ListExpr)
 	ZEEK_EXPR_ACCESSOR_DECLS(NameExpr)
 	ZEEK_EXPR_ACCESSOR_DECLS(RefExpr)
@@ -1304,7 +1306,9 @@ public:
 	LambdaExpr(std::unique_ptr<function_ingredients> ingredients,
 	           IDPList outer_ids);
 
+	const std::string& Name() const	{ return my_name; }
 	const IDPList& OuterIDs() const	{ return outer_ids; }
+	const function_ingredients& Ingredients() const	{ return *ingredients; }
 
 	ValPtr Eval(Frame* f) const override;
 	TraversalCode Traverse(TraversalCallback* cb) const override;
@@ -1427,7 +1431,7 @@ class IsExpr final : public UnaryExpr {
 public:
 	IsExpr(ExprPtr op, TypePtr t);
 
-	TypePtr TestType() const	{ return t; }
+	const TypePtr& TestType() const	{ return t; }
 
 	// Optimization-related:
 	ExprPtr Duplicate() override;
diff --git a/src/IPAddr.h b/src/IPAddr.h
index f4b9d0693d..d2cfda09b1 100644
--- a/src/IPAddr.h
+++ b/src/IPAddr.h
@@ -39,7 +39,11 @@ struct ConnIDKey {
 		}
 
 	bool operator<(const ConnIDKey& rhs) const { return memcmp(this, &rhs, sizeof(ConnIDKey)) < 0; }
+	bool operator<=(const ConnIDKey& rhs) const { return memcmp(this, &rhs, sizeof(ConnIDKey)) <= 0; }
 	bool operator==(const ConnIDKey& rhs) const { return memcmp(this, &rhs, sizeof(ConnIDKey)) == 0; }
+	bool operator!=(const ConnIDKey& rhs) const { return memcmp(this, &rhs, sizeof(ConnIDKey)) != 0; }
+	bool operator>=(const ConnIDKey& rhs) const { return memcmp(this, &rhs, sizeof(ConnIDKey)) >= 0; }
+	bool operator>(const ConnIDKey& rhs) const { return memcmp(this, &rhs, sizeof(ConnIDKey)) > 0; }
 
 	ConnIDKey& operator=(const ConnIDKey& rhs)
 		{
diff --git a/src/RE.cc b/src/RE.cc
index 9639f8223c..0348dc4284 100644
--- a/src/RE.cc
+++ b/src/RE.cc
@@ -479,7 +479,7 @@ RE_Matcher::RE_Matcher()
 	re_exact = new detail::Specific_RE_Matcher(detail::MATCH_EXACTLY);
 	}
 
-RE_Matcher::RE_Matcher(const char* pat)
+RE_Matcher::RE_Matcher(const char* pat) : orig_text(pat)
 	{
 	re_anywhere = new detail::Specific_RE_Matcher(detail::MATCH_ANYWHERE);
 	re_exact = new detail::Specific_RE_Matcher(detail::MATCH_EXACTLY);
@@ -511,6 +511,8 @@ void RE_Matcher::MakeCaseInsensitive()
 	{
 	re_anywhere->MakeCaseInsensitive();
 	re_exact->MakeCaseInsensitive();
+
+	is_case_insensitive = true;
 	}
 
 bool RE_Matcher::Compile(bool lazy)
diff --git a/src/RE.h b/src/RE.h
index fdbd023fd7..ab1b5a3439 100644
--- a/src/RE.h
+++ b/src/RE.h
@@ -197,6 +197,7 @@ public:
 
 	// Makes the matcher as specified to date case-insensitive.
 	void MakeCaseInsensitive();
+	bool IsCaseInsensitive() const	{ return is_case_insensitive; }
 
 	bool Compile(bool lazy = false);
 
@@ -227,6 +228,10 @@ public:
 	const char* PatternText() const	{ return re_exact->PatternText(); }
 	const char* AnywherePatternText() const	{ return re_anywhere->PatternText(); }
 
+	// Original text used to construct this matcher.  Empty unless
+	// the main ("explicit") constructor was used.
+	const char* OrigText() const	{ return orig_text.c_str(); }
+
 	unsigned int MemoryAllocation() const
 		{
 		return padded_sizeof(*this)
@@ -235,8 +240,12 @@ public:
 		}
 
 protected:
+	std::string orig_text;
+
 	detail::Specific_RE_Matcher* re_anywhere;
 	detail::Specific_RE_Matcher* re_exact;
+
+	bool is_case_insensitive = false;
 };
 
 } // namespace zeek
diff --git a/src/Type.cc b/src/Type.cc
index 4969d56dc2..7f545059f2 100644
--- a/src/Type.cc
+++ b/src/Type.cc
@@ -147,6 +147,18 @@ FuncType* Type::AsFuncType()
 	return (FuncType*) this;
 	}
 
+const FileType* Type::AsFileType() const
+	{
+	CHECK_TYPE_TAG(TYPE_FILE, "Type::AsFileType");
+	return (const FileType*) this;
+	}
+
+FileType* Type::AsFileType()
+	{
+	CHECK_TYPE_TAG(TYPE_FILE, "Type::AsFileType");
+	return (FileType*) this;
+	}
+
 const EnumType* Type::AsEnumType() const
 	{
 	CHECK_TYPE_TAG(TYPE_ENUM, "Type::AsEnumType");
@@ -1052,6 +1064,12 @@ void RecordType::DescribeFields(ODesc* d) const
 			else
 				td->type->Describe(d);
 
+			if ( td->attrs )
+				{
+				d->SP();
+				td->attrs->Describe(d);
+				}
+
 			d->Add(";");
 			}
 		}
@@ -1355,6 +1373,14 @@ void EnumType::AddNameInternal(const string& module_name, const char* name,
 	names[fullname] = val;
 	}
 
+void EnumType::AddNameInternal(const string& full_name, bro_int_t val)
+	{
+	names[full_name] = val;
+
+	if ( vals.find(val) == vals.end() )
+		vals[val] = make_intrusive<EnumVal>(IntrusivePtr{NewRef{}, this}, val);
+	}
+
 bro_int_t EnumType::Lookup(const string& module_name, const char* name) const
 	{
 	NameMap::const_iterator pos =
@@ -1399,6 +1425,27 @@ const EnumValPtr& EnumType::GetEnumVal(bro_int_t i)
 	return it->second;
 	}
 
+void EnumType::Describe(ODesc* d) const
+	{
+	auto t = Tag();
+
+	if ( d->IsBinary() )
+		{
+		d->Add(int(t));
+		if ( ! d->IsShort() )
+			d->Add(GetName());
+		}
+	else
+		{
+		d->Add(type_name(t));
+		if ( ! d->IsShort() )
+			{
+			d->SP();
+			d->Add(GetName());
+			}
+		}
+	}
+
 void EnumType::DescribeReST(ODesc* d, bool roles_only) const
 	{
 	d->Add(":zeek:type:`enum`");
diff --git a/src/Type.h b/src/Type.h
index 7726da52c9..72c52a6e45 100644
--- a/src/Type.h
+++ b/src/Type.h
@@ -219,6 +219,9 @@ public:
 	const FuncType* AsFuncType() const;
 	FuncType* AsFuncType();
 
+	const FileType* AsFileType() const;
+	FileType* AsFileType();
+
 	const EnumType* AsEnumType() const;
 	EnumType* AsEnumType();
 
@@ -595,7 +598,8 @@ public:
 	// Given an offset, returns the field's name.
 	const char* FieldName(int field) const;
 
-	type_decl_list* Types() { return types; }
+	const type_decl_list* Types() const	{ return types; }
+	type_decl_list* Types()			{ return types; }
 
 	// Given an offset, returns the field's TypeDecl.
 	const TypeDecl* FieldDecl(int field) const;
@@ -704,6 +708,7 @@ public:
 	// will be fully qualified with their module name.
 	enum_name_list Names() const;
 
+	void Describe(ODesc* d) const override;
 	void DescribeReST(ODesc* d, bool roles_only = false) const override;
 
 	const EnumValPtr& GetEnumVal(bro_int_t i);
@@ -712,6 +717,8 @@ protected:
 	void AddNameInternal(const std::string& module_name,
 			const char* name, bro_int_t val, bool is_export);
 
+	void AddNameInternal(const std::string& full_name, bro_int_t val);
+
 	void CheckAndAddName(const std::string& module_name,
 	                     const char* name, bro_int_t val, bool is_export,
 	                     detail::Expr* deprecation = nullptr,
diff --git a/src/Val.cc b/src/Val.cc
index e76a62d0f8..924e0e858e 100644
--- a/src/Val.cc
+++ b/src/Val.cc
@@ -71,6 +71,8 @@ Val::~Val()
 	CONVERTER(tag, ctype, name) \
 	CONST_CONVERTER(tag, ctype, name)
 
+CONVERTERS(TYPE_FUNC, FuncVal*, Val::AsFuncVal)
+CONVERTERS(TYPE_FILE, FileVal*, Val::AsFileVal)
 CONVERTERS(TYPE_PATTERN, PatternVal*, Val::AsPatternVal)
 CONVERTERS(TYPE_PORT, PortVal*, Val::AsPortVal)
 CONVERTERS(TYPE_SUBNET, SubNetVal*, Val::AsSubNetVal)
@@ -2332,6 +2334,9 @@ void TableVal::Describe(ODesc* d) const
 		d->PushIndent();
 		}
 
+	bool determ = d->WantDeterminism();
+	std::vector<std::string> elem_descs;
+
 	auto iter = table_val->begin();
 
 	for ( int i = 0; i < n; ++i )
@@ -2345,7 +2350,10 @@ void TableVal::Describe(ODesc* d) const
 		auto vl = table_hash->RecoverVals(*k);
 		int dim = vl->Length();
 
-		if ( i > 0 )
+		ODesc intermediary_d;
+		ODesc* d_ptr = determ ? &intermediary_d : d;
+
+		if ( ! determ && i > 0 )
 			{
 			if ( ! d->IsBinary() )
 				d->Add(",");
@@ -2356,42 +2364,65 @@ void TableVal::Describe(ODesc* d) const
 		if ( d->IsReadable() )
 			{
 			if ( dim != 1 || ! table_type->IsSet() )
-				d->Add("[");
+				d_ptr->Add("[");
 			}
 		else
 			{
-			d->Add(dim);
-			d->SP();
+			d_ptr->Add(dim);
+			d_ptr->SP();
 			}
 
-		vl->Describe(d);
+		vl->Describe(d_ptr);
 
 		if ( table_type->IsSet() )
 			{ // We're a set, not a table.
 			if ( d->IsReadable() )
 				if ( dim != 1 )
-					d->AddSP("]");
+					d_ptr->AddSP("]");
 			}
 		else
 			{
 			if ( d->IsReadable() )
-				d->AddSP("] =");
+				d_ptr->AddSP("] =");
 			if ( v->GetVal() )
-				v->GetVal()->Describe(d);
+				v->GetVal()->Describe(d_ptr);
 			}
 
 		if ( d->IsReadable() && ! d->IsShort() && d->IncludeStats() )
 			{
-			d->Add(" @");
-			d->Add(util::detail::fmt_access_time(v->ExpireAccessTime()));
+			d_ptr->Add(" @");
+			d_ptr->Add(util::detail::fmt_access_time(v->ExpireAccessTime()));
 			}
 
+		if ( determ )
+			elem_descs.emplace_back(d_ptr->Description());
+
 		++iter;
 		}
 
 	if ( iter != table_val->end() )
 		reporter->InternalError("hash table overflow in TableVal::Describe");
 
+	if ( determ )
+		{
+		sort(elem_descs.begin(), elem_descs.end());
+		bool did_elems = false;
+
+		for ( const auto& ed : elem_descs )
+			{
+			if ( did_elems )
+				{
+				if ( ! d->IsBinary() )
+					d->Add(",");
+
+				d->NL();
+				}
+
+			d->Add(ed);
+			did_elems = true;
+			}
+		}
+
 	if ( d->IsPortable() || d->IsReadable() )
 		{
 		d->PopIndent();
@@ -3499,7 +3530,8 @@ void describe_vals(const std::vector<ValPtr>& vals,
 		if ( i > offset && d->IsReadable() && d->Style() != RAW_STYLE )
 			d->Add(", ");
 
-		vals[i]->Describe(d);
+		if ( vals[i] )
+			vals[i]->Describe(d);
 		}
 	}
 
diff --git a/src/Val.h b/src/Val.h
index e035e8a76e..4ee197afdb 100644
--- a/src/Val.h
+++ b/src/Val.h
@@ -61,6 +61,8 @@ class PortVal;
 class AddrVal;
 class SubNetVal;
 class IntervalVal;
+class FuncVal;
+class FileVal;
 class PatternVal;
 class TableVal;
 class RecordVal;
@@ -143,6 +145,12 @@ UNDERLYING_ACCESSOR_DECL(PatternVal, const RE_Matcher*, AsPattern)
 UNDERLYING_ACCESSOR_DECL(TableVal, const PDict<TableEntryVal>*, AsTable)
 UNDERLYING_ACCESSOR_DECL(TypeVal, zeek::Type*, AsType)
 
+	FuncVal* AsFuncVal();
+	const FuncVal* AsFuncVal() const;
+
+	FileVal* AsFileVal();
+	const FileVal* AsFileVal() const;
+
 	PatternVal* AsPatternVal();
 	const PatternVal* AsPatternVal() const;
 
@@ -760,6 +768,32 @@ public:
 	 */
 	TableValPtr Intersection(const TableVal& v) const;
 
+	/**
+	 * Returns a new table that is the union of this table and the
+	 * given table.  Union is done only on index, so this generally
+	 * makes most sense to use for sets, not tables.
+	 * @param v  The union'ing table.
+	 * @return  The union of this table and the given one.
+	 */
+	TableValPtr Union(TableVal* v) const
+		{
+		auto v_clone = cast_intrusive<TableVal>(v->Clone());
+		AddTo(v_clone.get(), false, false);
+		return v_clone;
+		}
+
+	/**
+	 * Returns a copy of this table with the given table removed.
+	 * @param v  The table to remove.
+	 * @return  The subset of this table that doesn't include v.
+	 */
+	TableValPtr TakeOut(TableVal* v)
+		{
+		auto clone = cast_intrusive<TableVal>(Clone());
+		v->RemoveFrom(clone.get());
+		return clone;
+		}
+
 	// Returns true if this set contains the same members as the
 	// given set.  Note that comparisons are done using hash keys,
 	// so errors can arise for compound sets such as sets-of-sets.
diff --git a/src/script_opt/Expr.cc b/src/script_opt/Expr.cc
index 8002ef37a6..d77f20ea22 100644
--- a/src/script_opt/Expr.cc
+++ b/src/script_opt/Expr.cc
@@ -85,6 +85,12 @@ const AnyIndexExpr* Expr::AsAnyIndexExpr() const
 	return (const AnyIndexExpr*) this;
 	}
 
+const LambdaExpr* Expr::AsLambdaExpr() const
+	{
+	CHECK_TAG(tag, EXPR_LAMBDA, "ExprVal::AsLambdaExpr", expr_name)
+	return (const LambdaExpr*) this;
+	}
+
 ExprPtr Expr::GetOp1() const { return nullptr; }
 ExprPtr Expr::GetOp2() const { return nullptr; }
 ExprPtr Expr::GetOp3() const { return nullptr; }
diff --git a/testing/btest/Baseline/bifs.type_name/out b/testing/btest/Baseline/bifs.type_name/out
index f96c9b51cc..8b4e1ce81e 100644
--- a/testing/btest/Baseline/bifs.type_name/out
+++ b/testing/btest/Baseline/bifs.type_name/out
@@ -7,7 +7,7 @@ bool
 time
 interval
 pattern
-enum
+enum color
 port
 addr
 addr
diff --git a/testing/btest/Baseline/language.alternate-prototypes-default-args/errors b/testing/btest/Baseline/language.alternate-prototypes-default-args/errors
index 842e9f2548..a4ebed301e 100644
--- a/testing/btest/Baseline/language.alternate-prototypes-default-args/errors
+++ b/testing/btest/Baseline/language.alternate-prototypes-default-args/errors
@@ -1,2 +1,2 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
-error in ./bad.zeek, line 2 and ./bad.zeek, line 1: alternate function prototype arguments may not have attributes: arg 'a' (event(c:string; b:string; a:string;) and event(a:string; b:string; c:string;))
+error in ./bad.zeek, line 2 and ./bad.zeek, line 1: alternate function prototype arguments may not have attributes: arg 'a' (event(c:string; b:string; a:string &default=A, &optional;) and event(a:string; b:string; c:string &default=C, &optional;))
diff --git a/testing/btest/Baseline/language.closure-binding-deprecated/out b/testing/btest/Baseline/language.closure-binding-deprecated/out
new file mode 100644
index 0000000000..066ca90cec
--- /dev/null
+++ b/testing/btest/Baseline/language.closure-binding-deprecated/out
@@ -0,0 +1,12 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+reference capture
+4, 10
+6, 8
+7, 7
+reference double capture
+4
+2, 10, 47
+4
+2, 8, 47
+3
+1, 7, 47
diff --git a/testing/btest/Baseline/language.closure-binding/out b/testing/btest/Baseline/language.closure-binding/out
index 891492d324..d5c7c22634 100644
--- a/testing/btest/Baseline/language.closure-binding/out
+++ b/testing/btest/Baseline/language.closure-binding/out
@@ -1,43 +1,42 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
-4, 10
-6, 8
-7, 7
+shallow copy
 4, 10
 5, 8
 6, 7
+deep copy
 4, 10
 5, 9
 6, 8
+mixed copy, case 1
 4, 10
 5, 8
 6, 7
+mixed copy, case 2
 4, 10
 5, 9
 6, 8
-4
-2, 10, 47
-4
-2, 8, 47
-3
-1, 7, 47
+double shallow copy
 4
 2, 10, 47
 5
 3, 8, 47
 6
 4, 7, 47
+double deep copy, case 1
 4
 2, 10, 47
 5
 3, 9, 47
 6
 4, 8, 47
+double deep copy, case 2
 4
 2, 10, 91
 5
 3, 9, 91
 6
 4, 9, 91
+double deep copy, case 3
 4
 2, 10, 91
 5
diff --git a/testing/btest/Baseline/language.closure-sending-deprecated/recv.recv.out b/testing/btest/Baseline/language.closure-sending-deprecated/recv.recv.out
new file mode 100644
index 0000000000..d48a41b96d
--- /dev/null
+++ b/testing/btest/Baseline/language.closure-sending-deprecated/recv.recv.out
@@ -0,0 +1,27 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+hello :-)
+peer added
+receiver got ping: function 2
+inside: 1 | outside: 12 | global: 100
+77
+receiver got ping: function 1
+begin: 100 | base_step: 2
+begin: 100 | base_step: 2 | step: 76
+178
+receiver got ping: function 2
+inside: 3 | outside: 12 | global: 100
+79
+receiver got ping: function 1
+begin: 100 | base_step: 4
+begin: 100 | base_step: 4 | step: 76
+180
+receiver got ping: function 2
+inside: 5 | outside: 12 | global: 100
+81
+receiver got ping: function 1
+begin: 100 | base_step: 6
+begin: 100 | base_step: 6 | step: 76
+182
+receiver got ping: function 2
+inside: 7 | outside: 12 | global: 100
+83
diff --git a/testing/btest/Baseline/language.closure-sending-deprecated/send.send.out b/testing/btest/Baseline/language.closure-sending-deprecated/send.send.out
new file mode 100644
index 0000000000..39d70d48d5
--- /dev/null
+++ b/testing/btest/Baseline/language.closure-sending-deprecated/send.send.out
@@ -0,0 +1,32 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+hello :)
+peer added
+begin: 100 | base_step: 50
+sender got pong: function 2
+inside: 1 | outside: 12 | global: 10
+77
+begin: 100 | base_step: 50
+sender got pong: function 1
+begin: 178 | base_step: 2
+begin: 178 | base_step: 2 | step: 76
+256
+begin: 100 | base_step: 50
+sender got pong: function 2
+inside: 3 | outside: 12 | global: 10
+79
+begin: 100 | base_step: 50
+sender got pong: function 1
+begin: 180 | base_step: 4
+begin: 180 | base_step: 4 | step: 76
+260
+begin: 100 | base_step: 50
+sender got pong: function 2
+inside: 5 | outside: 12 | global: 10
+81
+begin: 100 | base_step: 50
+sender got pong: function 1
+begin: 182 | base_step: 6
+begin: 182 | base_step: 6 | step: 76
+264
+begin: 100 | base_step: 50
+peer lost
diff --git a/testing/btest/Baseline/language.copy-all-types/out b/testing/btest/Baseline/language.copy-all-types/out
index 767e229f78..3a5e6dbb8d 100644
--- a/testing/btest/Baseline/language.copy-all-types/out
+++ b/testing/btest/Baseline/language.copy-all-types/out
@@ -9,5 +9,5 @@ orig=/^?(.*PATTERN.*)$?/ (pattern) clone=/^?(.*PATTERN.*)$?/ (pattern) same_obje
 orig=2,5,3,4,1 (set[count]) clone=2,5,3,4,1 (set[count]) equal=T same_object=F (ok)
 orig=[1, 2, 3, 4, 5] (vector of count) clone=[1, 2, 3, 4, 5] (vector of count) equal=T same_object=F (ok)
 orig=a=va;b=vb (table[string] of string) clone=a=va;b=vb (table[string] of string) equal=T same_object=F (ok)
-orig=ENUMME (enum) clone=ENUMME (enum) equal=T same_object=T (ok)
-orig=[s1=s1, s2=s2, i1=[a=a], i2=[a=a], donotset=<uninitialized>, def=5] (record { s1:string; s2:string; i1:record { a:string; }; i2:record { a:string; }; donotset:record { a:string; }; def:count; }) clone=[s1=s1, s2=s2, i1=[a=a], i2=[a=a], donotset=<uninitialized>, def=5] (record { s1:string; s2:string; i1:record { a:string; }; i2:record { a:string; }; donotset:record { a:string; }; def:count; }) equal=T same_object=F (ok)
+orig=ENUMME (enum MyEnum) clone=ENUMME (enum MyEnum) equal=T same_object=T (ok)
+orig=[s1=s1, s2=s2, i1=[a=a], i2=[a=a], donotset=<uninitialized>, def=5] (record { s1:string; s2:string; i1:record { a:string; }; i2:record { a:string; } &optional; donotset:record { a:string; } &optional; def:count &default=5, &optional; }) clone=[s1=s1, s2=s2, i1=[a=a], i2=[a=a], donotset=<uninitialized>, def=5] (record { s1:string; s2:string; i1:record { a:string; }; i2:record { a:string; } &optional; donotset:record { a:string; } &optional; def:count &default=5, &optional; }) equal=T same_object=F (ok)
diff --git a/testing/btest/Baseline/language.record-function-recursion/out b/testing/btest/Baseline/language.record-function-recursion/out
index 15181bfcc1..9f32322cd6 100644
--- a/testing/btest/Baseline/language.record-function-recursion/out
+++ b/testing/btest/Baseline/language.record-function-recursion/out
@@ -1,3 +1,3 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
 [id=<uninitialized>, inner=<uninitialized>]
-record { id:count; inner:record { create:function(input:<recursion>;) : string; }; }
+record { id:count &optional; inner:record { create:function(input:<recursion>;) : string; } &optional; }
diff --git a/testing/btest/Baseline/language.type-cast-error-dynamic/output b/testing/btest/Baseline/language.type-cast-error-dynamic/output
index 19e917d7be..bf6438e3e6 100644
--- a/testing/btest/Baseline/language.type-cast-error-dynamic/output
+++ b/testing/btest/Baseline/language.type-cast-error-dynamic/output
@@ -1,5 +1,5 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
 expression error in <...>/type-cast-error-dynamic.zeek, line 11: invalid cast of value with type 'count' to type 'string' (a as string)
 expression error in <...>/type-cast-error-dynamic.zeek, line 11: invalid cast of value with type 'record { a:addr; b:port; }' to type 'string' (a as string)
-expression error in <...>/type-cast-error-dynamic.zeek, line 11: invalid cast of value with type 'record { data:opaque of Broker::Data; }' to type 'string' (nil $data field) (a as string)
+expression error in <...>/type-cast-error-dynamic.zeek, line 11: invalid cast of value with type 'record { data:opaque of Broker::Data &optional; }' to type 'string' (nil $data field) (a as string)
 data is string, F
diff --git a/testing/btest/Baseline/language.type-coerce-numerics/first_set.out b/testing/btest/Baseline/language.type-coerce-numerics/first_set.out
index 7516e00089..f053ab7046 100644
--- a/testing/btest/Baseline/language.type-coerce-numerics/first_set.out
+++ b/testing/btest/Baseline/language.type-coerce-numerics/first_set.out
@@ -1,6 +1,6 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
 error in int and ./first_set.zeek, line 46: overflow promoting from unsigned/double to signed arithmetic value (int and 9223372036854775808)
-expression error in ./first_set.zeek, line 46: Failed type conversion ((coerce [$ii=9223372036854775808] to record { ii:int; cc:count; dd:double; }))
+expression error in ./first_set.zeek, line 46: Failed type conversion ((coerce [$ii=9223372036854775808] to record { ii:int &optional; cc:count &optional; dd:double &optional; }))
 3
 int
 4
diff --git a/testing/btest/Baseline/language.uninitialized-local3/out b/testing/btest/Baseline/language.uninitialized-local3/out
index 70650b5bb5..e65bf87f36 100644
--- a/testing/btest/Baseline/language.uninitialized-local3/out
+++ b/testing/btest/Baseline/language.uninitialized-local3/out
@@ -1,6 +1,6 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
-warning in <...>/uninitialized-local3.zeek, line 33: possibly used without definition (x4)
-expression error in <...>/uninitialized-local3.zeek, line 33: value used but not set (x4)
+warning in <...>/uninitialized-local3.zeek, line 38: possibly used without definition (x4)
+expression error in <...>/uninitialized-local3.zeek, line 38: value used but not set (x4)
 x$a (x <...>/uninitialized-local3.zeek, line 20) possibly used without being set
 x$e (x <...>/uninitialized-local3.zeek, line 20) possibly used without being set
 x$e (x <...>/uninitialized-local3.zeek, line 24) possibly used without being set
diff --git a/testing/btest/Baseline/language.vector-of-enum/out b/testing/btest/Baseline/language.vector-of-enum/out
index d02272c5f3..283fcabc84 100644
--- a/testing/btest/Baseline/language.vector-of-enum/out
+++ b/testing/btest/Baseline/language.vector-of-enum/out
@@ -1,2 +1,2 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
-vector of enum, [Red, Green, Blue]
+vector of enum color, [Red, Green, Blue]
diff --git a/testing/btest/Baseline/plugins.hooks/output b/testing/btest/Baseline/plugins.hooks/output
index 780e01ccde..700c195e39 100644
--- a/testing/btest/Baseline/plugins.hooks/output
+++ b/testing/btest/Baseline/plugins.hooks/output
@@ -615,14 +615,14 @@
 0.000000   MetaHookPost  CallFunction(SumStats::add_observe_plugin_dependency, <frame>, (SumStats::VARIANCE, SumStats::AVERAGE)) -> <no result>
 0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::AVERAGE, lambda_<3452231521688988155>{ if (!SumStats::rv?$average) SumStats::rv$average = SumStats::valelseSumStats::rv$average += (SumStats::val - SumStats::rv$average) / (coerce SumStats::rv$num to double)})) -> <no result>
 0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::HLL_UNIQUE, lambda_<943258244234523627>{ if (!SumStats::rv?$card) { SumStats::rv$card = hll_cardinality_init(SumStats::r$hll_error_margin, SumStats::r$hll_confidence)SumStats::rv$hll_error_margin = SumStats::r$hll_error_marginSumStats::rv$hll_confidence = SumStats::r$hll_confidence}hll_cardinality_add(SumStats::rv$card, SumStats::obs)SumStats::rv$hll_unique = double_to_count(hll_cardinality_estimate(SumStats::rv$card))})) -> <no result>
-0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::LAST, lambda_<14831357773699754131>{ if (0 < SumStats::r$num_last_elements) { if (!SumStats::rv?$last_elements) SumStats::rv$last_elements = Queue::init((coerce [$max_len=SumStats::r$num_last_elements] to Queue::Settings))Queue::put(SumStats::rv$last_elements, SumStats::obs)}})) -> <no result>
+0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::LAST, lambda_<6246854644409869026>{ if (0 < SumStats::r$num_last_elements) { if (!SumStats::rv?$last_elements) SumStats::rv$last_elements = Queue::init((coerce [$max_len=SumStats::r$num_last_elements] to Queue::Settings))Queue::put(SumStats::rv$last_elements, SumStats::obs)}})) -> <no result>
 0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::MAX, lambda_<9734000075919044397>{ if (!SumStats::rv?$max) SumStats::rv$max = SumStats::valelseif (SumStats::rv$max < SumStats::val) SumStats::rv$max = SumStats::val})) -> <no result>
 0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::MIN, lambda_<2451066605226214733>{ if (!SumStats::rv?$min) SumStats::rv$min = SumStats::valelseif (SumStats::val < SumStats::rv$min) SumStats::rv$min = SumStats::val})) -> <no result>
 0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::SAMPLE, lambda_<11888441397542569241>{ SumStats::sample_add_sample(SumStats::obs, SumStats::rv)})) -> <no result>
 0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::STD_DEV, lambda_<5704045257244168718>{ SumStats::calc_std_dev(SumStats::rv)})) -> <no result>
 0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::SUM, lambda_<6958532551242393774>{ SumStats::rv$sum += SumStats::val})) -> <no result>
 0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::TOPK, lambda_<2861372781530360365>{ topk_add(SumStats::rv$topk, SumStats::obs)})) -> <no result>
-0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::UNIQUE, lambda_<10387912117292132662>{ if (!SumStats::rv?$unique_vals) SumStats::rv$unique_vals = (coerce set() to set[SumStats::Observation])if (SumStats::r?$unique_max) SumStats::rv$unique_max = SumStats::r$unique_maxif (!SumStats::r?$unique_max || sizeofSumStats::rv$unique_vals <= SumStats::r$unique_max) add SumStats::rv$unique_vals[SumStats::obs]SumStats::rv$unique = sizeofSumStats::rv$unique_vals})) -> <no result>
+0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::UNIQUE, lambda_<14393221830775341876>{ if (!SumStats::rv?$unique_vals) SumStats::rv$unique_vals = (coerce set() to set[SumStats::Observation])if (SumStats::r?$unique_max) SumStats::rv$unique_max = SumStats::r$unique_maxif (!SumStats::r?$unique_max || sizeofSumStats::rv$unique_vals <= SumStats::r$unique_max) add SumStats::rv$unique_vals[SumStats::obs]SumStats::rv$unique = sizeofSumStats::rv$unique_vals})) -> <no result>
 0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::VARIANCE, lambda_<6557258612059469785>{ if (1 < SumStats::rv$num) SumStats::rv$var_s += ((SumStats::val - SumStats::rv$prev_avg) * (SumStats::val - SumStats::rv$average))SumStats::calc_variance(SumStats::rv)SumStats::rv$prev_avg = SumStats::rv$average})) -> <no result>
 0.000000   MetaHookPost  CallFunction(SumStats::register_observe_plugins, <frame>, ()) -> <no result>
 0.000000   MetaHookPost  CallFunction(__init_primary_bifs, <null>, ()) -> <no result>
@@ -1618,14 +1618,14 @@
 0.000000   MetaHookPre   CallFunction(SumStats::add_observe_plugin_dependency, <frame>, (SumStats::VARIANCE, SumStats::AVERAGE))
 0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::AVERAGE, lambda_<3452231521688988155>{ if (!SumStats::rv?$average) SumStats::rv$average = SumStats::valelseSumStats::rv$average += (SumStats::val - SumStats::rv$average) / (coerce SumStats::rv$num to double)}))
 0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::HLL_UNIQUE, lambda_<943258244234523627>{ if (!SumStats::rv?$card) { SumStats::rv$card = hll_cardinality_init(SumStats::r$hll_error_margin, SumStats::r$hll_confidence)SumStats::rv$hll_error_margin = SumStats::r$hll_error_marginSumStats::rv$hll_confidence = SumStats::r$hll_confidence}hll_cardinality_add(SumStats::rv$card, SumStats::obs)SumStats::rv$hll_unique = double_to_count(hll_cardinality_estimate(SumStats::rv$card))}))
-0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::LAST, lambda_<14831357773699754131>{ if (0 < SumStats::r$num_last_elements) { if (!SumStats::rv?$last_elements) SumStats::rv$last_elements = Queue::init((coerce [$max_len=SumStats::r$num_last_elements] to Queue::Settings))Queue::put(SumStats::rv$last_elements, SumStats::obs)}}))
+0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::LAST, lambda_<6246854644409869026>{ if (0 < SumStats::r$num_last_elements) { if (!SumStats::rv?$last_elements) SumStats::rv$last_elements = Queue::init((coerce [$max_len=SumStats::r$num_last_elements] to Queue::Settings))Queue::put(SumStats::rv$last_elements, SumStats::obs)}}))
 0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::MAX, lambda_<9734000075919044397>{ if (!SumStats::rv?$max) SumStats::rv$max = SumStats::valelseif (SumStats::rv$max < SumStats::val) SumStats::rv$max = SumStats::val}))
 0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::MIN, lambda_<2451066605226214733>{ if (!SumStats::rv?$min) SumStats::rv$min = SumStats::valelseif (SumStats::val < SumStats::rv$min) SumStats::rv$min = SumStats::val}))
 0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::SAMPLE, lambda_<11888441397542569241>{ SumStats::sample_add_sample(SumStats::obs, SumStats::rv)}))
 0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::STD_DEV, lambda_<5704045257244168718>{ SumStats::calc_std_dev(SumStats::rv)}))
 0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::SUM, lambda_<6958532551242393774>{ SumStats::rv$sum += SumStats::val}))
 0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::TOPK, lambda_<2861372781530360365>{ topk_add(SumStats::rv$topk, SumStats::obs)}))
-0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::UNIQUE, lambda_<10387912117292132662>{ if (!SumStats::rv?$unique_vals) SumStats::rv$unique_vals = (coerce set() to set[SumStats::Observation])if (SumStats::r?$unique_max) SumStats::rv$unique_max = SumStats::r$unique_maxif (!SumStats::r?$unique_max || sizeofSumStats::rv$unique_vals <= SumStats::r$unique_max) add SumStats::rv$unique_vals[SumStats::obs]SumStats::rv$unique = sizeofSumStats::rv$unique_vals}))
+0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::UNIQUE, lambda_<14393221830775341876>{ if (!SumStats::rv?$unique_vals) SumStats::rv$unique_vals = (coerce set() to set[SumStats::Observation])if (SumStats::r?$unique_max) SumStats::rv$unique_max = SumStats::r$unique_maxif (!SumStats::r?$unique_max || sizeofSumStats::rv$unique_vals <= SumStats::r$unique_max) add SumStats::rv$unique_vals[SumStats::obs]SumStats::rv$unique = sizeofSumStats::rv$unique_vals}))
 0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugin, <frame>, (SumStats::VARIANCE, lambda_<6557258612059469785>{ if (1 < SumStats::rv$num) SumStats::rv$var_s += ((SumStats::val - SumStats::rv$prev_avg) * (SumStats::val - SumStats::rv$average))SumStats::calc_variance(SumStats::rv)SumStats::rv$prev_avg = SumStats::rv$average}))
 0.000000   MetaHookPre   CallFunction(SumStats::register_observe_plugins, <frame>, ())
 0.000000   MetaHookPre   CallFunction(__init_primary_bifs, <null>, ())
@@ -2620,14 +2620,14 @@
 0.000000 | HookCallFunction SumStats::add_observe_plugin_dependency(SumStats::VARIANCE, SumStats::AVERAGE)
 0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::AVERAGE, lambda_<3452231521688988155>{ if (!SumStats::rv?$average) SumStats::rv$average = SumStats::valelseSumStats::rv$average += (SumStats::val - SumStats::rv$average) / (coerce SumStats::rv$num to double)})
 0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::HLL_UNIQUE, lambda_<943258244234523627>{ if (!SumStats::rv?$card) { SumStats::rv$card = hll_cardinality_init(SumStats::r$hll_error_margin, SumStats::r$hll_confidence)SumStats::rv$hll_error_margin = SumStats::r$hll_error_marginSumStats::rv$hll_confidence = SumStats::r$hll_confidence}hll_cardinality_add(SumStats::rv$card, SumStats::obs)SumStats::rv$hll_unique = double_to_count(hll_cardinality_estimate(SumStats::rv$card))})
-0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::LAST, lambda_<14831357773699754131>{ if (0 < SumStats::r$num_last_elements) { if (!SumStats::rv?$last_elements) SumStats::rv$last_elements = Queue::init((coerce [$max_len=SumStats::r$num_last_elements] to Queue::Settings))Queue::put(SumStats::rv$last_elements, SumStats::obs)}})
+0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::LAST, lambda_<6246854644409869026>{ if (0 < SumStats::r$num_last_elements) { if (!SumStats::rv?$last_elements) SumStats::rv$last_elements = Queue::init((coerce [$max_len=SumStats::r$num_last_elements] to Queue::Settings))Queue::put(SumStats::rv$last_elements, SumStats::obs)}})
 0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::MAX, lambda_<9734000075919044397>{ if (!SumStats::rv?$max) SumStats::rv$max = SumStats::valelseif (SumStats::rv$max < SumStats::val) SumStats::rv$max = SumStats::val})
 0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::MIN, lambda_<2451066605226214733>{ if (!SumStats::rv?$min) SumStats::rv$min = SumStats::valelseif (SumStats::val < SumStats::rv$min) SumStats::rv$min = SumStats::val})
 0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::SAMPLE, lambda_<11888441397542569241>{ SumStats::sample_add_sample(SumStats::obs, SumStats::rv)})
 0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::STD_DEV, lambda_<5704045257244168718>{ SumStats::calc_std_dev(SumStats::rv)})
 0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::SUM, lambda_<6958532551242393774>{ SumStats::rv$sum += SumStats::val})
 0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::TOPK, lambda_<2861372781530360365>{ topk_add(SumStats::rv$topk, SumStats::obs)})
-0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::UNIQUE, lambda_<10387912117292132662>{ if (!SumStats::rv?$unique_vals) SumStats::rv$unique_vals = (coerce set() to set[SumStats::Observation])if (SumStats::r?$unique_max) SumStats::rv$unique_max = SumStats::r$unique_maxif (!SumStats::r?$unique_max || sizeofSumStats::rv$unique_vals <= SumStats::r$unique_max) add SumStats::rv$unique_vals[SumStats::obs]SumStats::rv$unique = sizeofSumStats::rv$unique_vals})
+0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::UNIQUE, lambda_<14393221830775341876>{ if (!SumStats::rv?$unique_vals) SumStats::rv$unique_vals = (coerce set() to set[SumStats::Observation])if (SumStats::r?$unique_max) SumStats::rv$unique_max = SumStats::r$unique_maxif (!SumStats::r?$unique_max || sizeofSumStats::rv$unique_vals <= SumStats::r$unique_max) add SumStats::rv$unique_vals[SumStats::obs]SumStats::rv$unique = sizeofSumStats::rv$unique_vals})
 0.000000 | HookCallFunction SumStats::register_observe_plugin(SumStats::VARIANCE, lambda_<6557258612059469785>{ if (1 < SumStats::rv$num) SumStats::rv$var_s += ((SumStats::val - SumStats::rv$prev_avg) * (SumStats::val - SumStats::rv$average))SumStats::calc_variance(SumStats::rv)SumStats::rv$prev_avg = SumStats::rv$average})
 0.000000 | HookCallFunction SumStats::register_observe_plugins()
 0.000000 | HookCallFunction __init_primary_bifs()
diff --git a/testing/btest/Baseline/scripts.base.frameworks.input.errors/.stderr b/testing/btest/Baseline/scripts.base.frameworks.input.errors/.stderr
index 62cc8f4164..902551f30a 100644
--- a/testing/btest/Baseline/scripts.base.frameworks.input.errors/.stderr
+++ b/testing/btest/Baseline/scripts.base.frameworks.input.errors/.stderr
@@ -9,29 +9,29 @@ error: Input stream filetable: Problem unrolling
 The input framework does not support optional record fields: "r"
 error: Input stream optionalrecordtable: Problem unrolling
 Encountered incompatible type "file" in type definition for field "s" in ReaderFrontend. Ignoring optional field.
-error: Input stream optionalfiletable: Table type does not match value type. Need type 'record { i:int; s:file of string; }', got 'record { i:int; r:record { i:int; s:file of string; }; }'
+error: Input stream optionalfiletable: Table type does not match value type. Need type 'record { i:int; s:file of string &optional; }', got 'record { i:int; r:record { i:int; s:file of string; } &optional; }'
 error: Input stream optionalfiletable2: Table type does not match index type. Need type 'count':count, got 'string':string
 error: Input stream optionalfiletable3: Stream event is a function, not an event
 error: Input stream optionalfiletable3: Table event must take 4 arguments
 error: Input stream optionalfiletable4: Table event's first attribute must be of type Input::TableDescription
 error: Input stream optionalfiletable5: Table event's second attribute must be of type Input::Event
-error: Input stream optionalfiletable6: Table event's index attributes do not match. Need 'record { c:count; }', got 'record { i:int; r:record { i:int; s:file of string; }; }'
-error: Input stream optionalfiletable7: Table event's value attributes do not match. Need 'record { i:int; s:file of string; }', got 'record { i:int; r:record { i:int; s:file of string; }; }'
+error: Input stream optionalfiletable6: Table event's index attributes do not match. Need 'record { c:count; }', got 'record { i:int; r:record { i:int; s:file of string; } &optional; }'
+error: Input stream optionalfiletable7: Table event's value attributes do not match. Need 'record { i:int; s:file of string &optional; }', got 'record { i:int; r:record { i:int; s:file of string; } &optional; }'
 error: Input stream optionalfiletable8: Stream does not want a record (want_record=F), but has more then one value field.
 error: Input stream optionalfiletable9: Table has less elements than index definition
 error: Input stream optionalfiletable10: Table type has more indexes than index definition
 error: Input stream optionalfiletable11: Table type does not match value type. Need type 'count', got 'int'
 error: Input stream optionalfiletable12: Table type does not match value type. Need type 'count', got 'record { i:int; s:string; a:addr; }'
-error: Input stream optionalfiletable14: Table type does not match value type. Need type 'int', got 'record { i:int; s:file of string; }'
+error: Input stream optionalfiletable14: Table type does not match value type. Need type 'int', got 'record { i:int; s:file of string &optional; }'
 error: Input stream optionalfiletable15: Table type does not match value type. Need type 'record { c:count; }', got 'record { i:int; s:string; a:addr; }'
 error: Input stream event1: Stream event is a function, not an event
 error: Input stream event2: Event does not take enough arguments
 error: Input stream event3: Event's first attribute must be of type Input::EventDescription
 error: Input stream event4: Event's second attribute must be of type Input::Event
-error: Input stream event5: Incompatible type 'record':record { i:int; r:record { i:int; s:file of string; }; } for event, which needs type 'record':record { i:int; s:file of string; }
+error: Input stream event5: Incompatible type 'record':record { i:int; r:record { i:int; s:file of string; } &optional; } for event, which needs type 'record':record { i:int; s:file of string &optional; }
 
 error: Input stream event6: Event has wrong number of arguments
-error: Input stream event7: Incompatible type for event in field 3. Need type 'int':int, got 'record':record { i:int; r:record { i:int; s:file of string; }; }
+error: Input stream event7: Incompatible type for event in field 3. Need type 'int':int, got 'record':record { i:int; r:record { i:int; s:file of string; } &optional; }
 error: Input stream event8: Incompatible type for event in field 5. Need type 'addr':addr, got 'string':string
 error: Input stream event9: Event has wrong number of arguments
 error: Input stream error1: Error event's first attribute must be of type Input::EventDescription
diff --git a/testing/btest/core/conn-uid.zeek b/testing/btest/core/conn-uid.zeek
index 5852236ff0..6c7c326492 100644
--- a/testing/btest/core/conn-uid.zeek
+++ b/testing/btest/core/conn-uid.zeek
@@ -1,7 +1,7 @@
 #
 # In "normal" test mode, connection uids should be determistic.
 #
-# @TEST-EXEC: zeek -b -C -r $TRACES/wikipedia.trace %INPUT >output
+# @TEST-EXEC: zeek -b -D -C -r $TRACES/wikipedia.trace %INPUT >output
 # @TEST-EXEC: btest-diff output
 #
 # Without a seed, they should differ each time:
diff --git a/testing/btest/language/closure-binding-deprecated.zeek b/testing/btest/language/closure-binding-deprecated.zeek
new file mode 100644
index 0000000000..90a5c7e78f
--- /dev/null
+++ b/testing/btest/language/closure-binding-deprecated.zeek
@@ -0,0 +1,47 @@
+# @TEST-EXEC: zeek -b %INPUT >out
+# @TEST-EXEC: btest-diff out
+
+type mutable_aggregate: record { x: count; };
+
+function reference_capture() : function()
+	{
+	local a = 3;
+	local b = mutable_aggregate($x=11);
+	local f = function() { print ++a, --b$x; };
+	f();
+	++a;
+	--b$x;
+	f();
+
+	return f;
+	}
+
+function reference_capture_double() : function() : function()
+	{
+	local a = 3;
+	local b = mutable_aggregate($x=11);
+	local f = function() : function() {
+		local c = mutable_aggregate($x=88);
+		print ++a;
+		local f2 = function() { print a -= 2, --b$x, c$x += 3; };
+		c$x = c$x / 2;
+		return f2;
+		};
+	f()();
+	++a;
+	--b$x;
+	f()();
+
+	return f;
+	}
+
+event zeek_init()
+	{
+	print "reference capture";
+	local rc = reference_capture();
+	rc();
+
+	print "reference double capture";
+	local rc2 = reference_capture_double();
+	rc2()();
+	}
diff --git a/testing/btest/language/closure-binding.zeek b/testing/btest/language/closure-binding.zeek
index 6e1596b6f9..241c92484d 100644
--- a/testing/btest/language/closure-binding.zeek
+++ b/testing/btest/language/closure-binding.zeek
@@ -3,19 +3,6 @@
 
 type mutable_aggregate: record { x: count; };
 
-function reference_capture() : function()
-	{
-	local a = 3;
-	local b = mutable_aggregate($x=11);
-	local f = function() { print ++a, --b$x; };
-	f();
-	++a;
-	--b$x;
-	f();
-
-	return f;
-	}
-
 function shallow_copy_capture() : function()
 	{
 	local a = 3;
@@ -68,25 +55,6 @@ function mixed_copy_capture_b() : function()
 	return f;
 	}
 
-function reference_capture_double() : function() : function()
-	{
-	local a = 3;
-	local b = mutable_aggregate($x=11);
-	local f = function() : function() {
-		local c = mutable_aggregate($x=88);
-		print ++a;
-		local f2 = function() { print a -= 2, --b$x, c$x += 3; };
-		c$x = c$x / 2;
-		return f2;
-		};
-	f()();
-	++a;
-	--b$x;
-	f()();
-
-	return f;
-	}
-
 function shallow_copy_capture_double() : function() : function()
 	{
 	local a = 3;
@@ -167,33 +135,35 @@ function deep_copy3_capture_double() : function() : function()
 
 event zeek_init()
 	{
-	local rc = reference_capture();
-	rc();
-
+	print "shallow copy";
 	local scc = shallow_copy_capture();
 	scc();
 
+	print "deep copy";
 	local dcc = deep_copy_capture();
 	dcc();
 
+	print "mixed copy, case 1";
 	local mcca = mixed_copy_capture_a();
 	mcca();
 
+	print "mixed copy, case 2";
 	local mccb = mixed_copy_capture_b();
 	mccb();
 
-	local rc2 = reference_capture_double();
-	rc2()();
-
+	print "double shallow copy";
 	local scc2 = shallow_copy_capture_double();
 	scc2()();
 
+	print "double deep copy, case 1";
 	local dcc2_1 = deep_copy1_capture_double();
 	dcc2_1()();
 
+	print "double deep copy, case 2";
 	local dcc2_2 = deep_copy2_capture_double();
 	dcc2_2()();
 
+	print "double deep copy, case 3";
 	local dcc2_3 = deep_copy3_capture_double();
 	dcc2_3()();
 	}
diff --git a/testing/btest/language/closure-sending.zeek b/testing/btest/language/closure-sending-deprecated.zeek
similarity index 96%
rename from testing/btest/language/closure-sending.zeek
rename to testing/btest/language/closure-sending-deprecated.zeek
index f5a3e44035..09f403fc9b 100644
--- a/testing/btest/language/closure-sending.zeek
+++ b/testing/btest/language/closure-sending-deprecated.zeek
@@ -1,7 +1,7 @@
 # @TEST-PORT: BROKER_PORT
 #
-# @TEST-EXEC: btest-bg-run recv "zeek -B broker -b ../recv.zeek >recv.out"
-# @TEST-EXEC: btest-bg-run send "zeek -B broker -b ../send.zeek >send.out"
+# @TEST-EXEC: btest-bg-run recv "zeek -D -B broker -b ../recv.zeek >recv.out"
+# @TEST-EXEC: btest-bg-run send "zeek -D -B broker -b ../send.zeek >send.out"
 #
 # @TEST-EXEC: btest-bg-wait 45
 # @TEST-EXEC: btest-diff recv/recv.out
diff --git a/testing/btest/language/closure-sending-naming.zeek b/testing/btest/language/closure-sending-naming.zeek
index e616574002..92268c9a93 100644
--- a/testing/btest/language/closure-sending-naming.zeek
+++ b/testing/btest/language/closure-sending-naming.zeek
@@ -1,7 +1,7 @@
 # @TEST-PORT: BROKER_PORT
 #
-# @TEST-EXEC: btest-bg-run recv "zeek -B broker -b ../recv.zeek >recv.out 2>recv.error"
-# @TEST-EXEC: btest-bg-run send "zeek -B broker -b ../send.zeek >send.out"
+# @TEST-EXEC: btest-bg-run recv "zeek -D -B broker -b ../recv.zeek >recv.out 2>recv.error"
+# @TEST-EXEC: btest-bg-run send "zeek -D -B broker -b ../send.zeek >send.out"
 #
 # @TEST-EXEC: btest-bg-wait 20
 # @TEST-EXEC: btest-diff recv/recv.error
diff --git a/testing/btest/language/closure-sending2.zeek b/testing/btest/language/closure-sending2.zeek
index c6a421a708..e447b8224c 100644
--- a/testing/btest/language/closure-sending2.zeek
+++ b/testing/btest/language/closure-sending2.zeek
@@ -1,7 +1,7 @@
 # @TEST-PORT: BROKER_PORT
 #
-# @TEST-EXEC: btest-bg-run recv "zeek -B broker -b ../recv.zeek >recv.out"
-# @TEST-EXEC: btest-bg-run send "zeek -B broker -b ../send.zeek >send.out"
+# @TEST-EXEC: btest-bg-run recv "zeek -D -B broker -b ../recv.zeek >recv.out"
+# @TEST-EXEC: btest-bg-run send "zeek -D -B broker -b ../send.zeek >send.out"
 #
 # @TEST-EXEC: btest-bg-wait 45
 # @TEST-EXEC: btest-diff recv/recv.out
diff --git a/testing/btest/language/function-sending.zeek b/testing/btest/language/function-sending.zeek
index a45911878a..234e0a5431 100644
--- a/testing/btest/language/function-sending.zeek
+++ b/testing/btest/language/function-sending.zeek
@@ -1,7 +1,7 @@
 # @TEST-PORT: BROKER_PORT
 #
-# @TEST-EXEC: btest-bg-run recv "zeek -B broker -b ../recv.zeek >recv.out"
-# @TEST-EXEC: btest-bg-run send "zeek -B broker -b ../send.zeek >send.out"
+# @TEST-EXEC: btest-bg-run recv "zeek -D -B broker -b ../recv.zeek >recv.out"
+# @TEST-EXEC: btest-bg-run send "zeek -D -B broker -b ../send.zeek >send.out"
 #
 # @TEST-EXEC: btest-bg-wait 20
 # @TEST-EXEC: btest-diff recv/recv.out
diff --git a/testing/btest/language/paraglob-serialization.zeek b/testing/btest/language/paraglob-serialization.zeek
index c5d5d516dd..788aa4e95f 100644
--- a/testing/btest/language/paraglob-serialization.zeek
+++ b/testing/btest/language/paraglob-serialization.zeek
@@ -1,7 +1,7 @@
 # @TEST-PORT: BROKER_PORT
 #
-# @TEST-EXEC: btest-bg-run recv "zeek -B broker -b ../recv.zeek >recv.out"
-# @TEST-EXEC: btest-bg-run send "zeek -B broker -b ../send.zeek >send.out"
+# @TEST-EXEC: btest-bg-run recv "zeek -D -B broker -b ../recv.zeek >recv.out"
+# @TEST-EXEC: btest-bg-run send "zeek -D -B broker -b ../send.zeek >send.out"
 #
 # @TEST-EXEC: btest-bg-wait 45
 # @TEST-EXEC: btest-diff recv/recv.out
diff --git a/testing/btest/language/uninitialized-local3.zeek b/testing/btest/language/uninitialized-local3.zeek
index b251960633..f3aae38f5b 100644
--- a/testing/btest/language/uninitialized-local3.zeek
+++ b/testing/btest/language/uninitialized-local3.zeek
@@ -30,5 +30,13 @@ event zeek_init()
 	print x3;
 
 	local x4: count;
-	print x4;	# note, no execution after this point due to error
+	# note, no execution after this point due to error
+
+	# We use this slightly baroque expression because compiled code
+	# may have x4 genuinely uninitialized, and we want deterministic
+	# output in that case.
+	if ( x4 > 5 )
+		print T;
+	else
+		print T;
 	}