Type/is_supported_index_type: Deal with recursive record types

This plugs the issue reported in #2690, there might be more though.

Closes #2690

src/Type.cc

@@ -7,6 +7,7 @@
 #include <list>
 #include <map>
 #include <string>
+#include <unordered_set>
 
 #include "zeek/Attr.h"
 #include "zeek/Desc.h"
@@ -469,11 +470,19 @@ detail::TraversalCode IndexType::Traverse(detail::TraversalCallback* cb) const
 	HANDLE_TC_TYPE_POST(tc);
 	}
 
-static bool is_supported_index_type(const TypePtr& t, const char** tname)
+static bool is_supported_index_type(const TypePtr& t, const char** tname,
+                                    std::unordered_set<TypePtr>& seen)
 	{
 	if ( t->InternalType() != TYPE_INTERNAL_OTHER )
 		return true;
 
+	// Handle recursive calls as good: If they turn out not
+	// to be, that should've been discovered further down.
+	if ( seen.count(t) > 0 )
+		return true;
+
+	seen.insert(t);
+
 	auto tag = t->Tag();
 
 	switch ( tag )
@@ -490,7 +499,7 @@ static bool is_supported_index_type(const TypePtr& t, const char** tname)
 			auto rt = t->AsRecordType();
 
 			for ( auto i = 0; i < rt->NumFields(); ++i )
-				if ( ! is_supported_index_type(rt->GetFieldType(i), tname) )
+				if ( ! is_supported_index_type(rt->GetFieldType(i), tname, seen) )
 					return false;
 
 			return true;
@@ -499,7 +508,7 @@ static bool is_supported_index_type(const TypePtr& t, const char** tname)
 		case TYPE_LIST:
 			{
 			for ( const auto& type : t->AsTypeList()->GetTypes() )
-				if ( ! is_supported_index_type(type, tname) )
+				if ( ! is_supported_index_type(type, tname, seen) )
 					return false;
 
 			return true;
@@ -509,7 +518,7 @@ static bool is_supported_index_type(const TypePtr& t, const char** tname)
 			{
 			auto tt = t->AsTableType();
 
-			if ( ! is_supported_index_type(tt->GetIndices(), tname) )
+			if ( ! is_supported_index_type(tt->GetIndices(), tname, seen) )
 				return false;
 
 			const auto& yt = tt->Yield();
@@ -517,11 +526,11 @@ static bool is_supported_index_type(const TypePtr& t, const char** tname)
 			if ( ! yt )
 				return true;
 
-			return is_supported_index_type(yt, tname);
+			return is_supported_index_type(yt, tname, seen);
 			}
 
 		case TYPE_VECTOR:
-			return is_supported_index_type(t->AsVectorType()->Yield(), tname);
+			return is_supported_index_type(t->AsVectorType()->Yield(), tname, seen);
 
 		default:
 			*tname = type_name(tag);
@@ -545,7 +554,8 @@ TableType::TableType(TypeListPtr ind, TypePtr yield)
 		if ( t == TYPE_INTERNAL_ERROR )
 			break;
 
-		if ( ! is_supported_index_type(tli, &unsupported_type_name) )
+		std::unordered_set<TypePtr> seen;
+		if ( ! is_supported_index_type(tli, &unsupported_type_name, seen) )
 			{
 			auto msg = util::fmt("index type containing '%s' is not supported",
 			                     unsupported_type_name);

testing/btest/Baseline/language.record-recursive-table-2/output

@@ -0,0 +1,7 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+===, 0, {
+
+}
+===, 1, {
+[[id=1, foo=<uninitialized>]] = [id=2, foo=[id=1, foo=<uninitialized>]]
+}

testing/btest/Baseline/language.record-recursive-table/output

@@ -0,0 +1,38 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+===, 1, {
+[[bar=1, parent={
+
+}]] = {
+1
+}
+}
+{
+[[bar=1, parent={
+
+}]] = {
+1
+}
+}
+===, 2, {
+[[bar=1, parent={
+
+}]] = {
+1
+},
+[[bar=1, parent={
+[T] = [bar=2, parent={
+
+}]
+}]] = {
+2
+}
+}
+===, 1, {
+[[bar=1, parent={
+[T] = [bar=2, parent={
+
+}]
+}]] = {
+2
+}
+}

testing/btest/language/record-recursive-table.zeek

@@ -0,0 +1,56 @@
+# @TEST-EXEC: zeek -b %INPUT >output
+# @TEST-EXEC: btest-diff output
+
+type Foo: record {
+	bar: count;
+};
+
+redef record Foo += {
+	parent: table[bool] of Foo &default=table();
+};
+
+event zeek_init()
+	{
+	local tbl: table[Foo] of set[count];
+	local f = Foo($bar=1);
+	tbl[f] = set(1);
+	print "===", |tbl|, tbl;
+	print tbl;
+
+	local parent_tbl: table[bool] of Foo = [
+		[T] = Foo($bar=2),
+	];
+	f$parent = parent_tbl;
+	tbl[f] = set(2);
+
+	# This now has two entries in the table, because
+	# after setting f$parent, that's a different key.
+	print "===", |tbl|, tbl;
+
+	# Mutate f and use it to delete the first entry again.
+	f$parent = table();
+	delete tbl[f];
+
+	# This will be size 1
+	print "===", |tbl|, tbl;
+	}
+
+#@TEST-START-NEXT
+
+type Foo: record {
+	id: string;
+};
+
+redef record Foo += {
+	foo: Foo &optional;
+};
+
+event zeek_init()
+	{
+	local tbl: table[Foo] of Foo;
+	local f1 = Foo($id="1");
+	local f2 = Foo($id="2", $foo=f1);
+	print "===", |tbl|, tbl;
+	tbl[f1] = f2;
+	print "===", |tbl|, tbl;
+	}