ifcparse: keep unresolved references in the attribute slots

The parser could not resolve a #name when it read it, because the
instance may be defined further down the file, so it left the slot empty
and appended (owner, attribute, name) to a side table that a second pass
walked. The table held one entry per reference for the whole read: 64 MB
on a 58 MB model, the high-water mark of opening.

Now the reference stays where the tokenizer put it: the attribute slot
holds the instance_reference, or the reference_or_simple_type aggregate
for a list (mixed with inline typed values or not), until every instance
has been read, and resolve_instance_references() walks each instance's
slots and swaps names for instances. Ordering is what the tokenizer
produced; nothing is re-derived. A missing name becomes null in a scalar
and is dropped from an aggregate, as before; the error keeps its offset.
The three transient alternatives are appended to the attribute pack and
to argument_type in lock step and are never visible once a file is
loaded. Simple type instances read inline (IfcPropertySetDefinitionSet)
have their own slots, so their references need no diversion.

The table remains for the header entities and for streaming consumers of
instance_streamer::references(), which leave resolve_references_in_place
off.

TXG 58 MB / 210_King 147 MB / OKgate22 231 MB, single thread: time
unchanged (1.05 / 2.69 / 4.99 s), memory after the parse 287 -> 274,
698 -> 654, 1086 -> 1036 MB, peak 400 -> 365, 965 -> 871, 1471 -> 1347 MB.

This commit was written by an AI coding tool and has not been verified by
a human.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013wcN7XquTfUi4vsKQ4KchL

src/ifcparse/tests/test_ifcopenshell_parse.cpp

@@ -5,6 +5,8 @@
 #include <ifcparse/file.h>
 #include <ifcparse/parse.h>
 #include <cstdint>
+#include <filesystem>
+#include <fstream>
 #include <sstream>
 #include <string>
 #include <vector>
@@ -342,3 +344,93 @@ TEST_CASE("The index token policy ends every token where the full policy does, w
     lexer.next();
     CHECK(lexer.next().as_string() == "a\xc2\xa7" "b");
 }
+
+namespace {
+const char* const reference_resolution_spf =
+    "ISO-10303-21;\n"
+    "HEADER;\n"
+    "FILE_DESCRIPTION(('ViewDefinition [CoordinationView]'),'2;1');\n"
+    "FILE_NAME('','',(''),(''),'','','');\n"
+    "FILE_SCHEMA(('IFC4'));\n"
+    "ENDSEC;\n"
+    "DATA;\n"
+    "#1=IFCCARTESIANPOINT((0.,0.,0.));\n"
+    "#2=IFCCARTESIANPOINT((1.,0.,0.));\n"
+    "#3=IFCCARTESIANPOINT((0.,1.,0.));\n"
+    "#4=IFCPOLYLINE((#1,#2,#3));\n"
+    "#5=IFCTRIMMEDCURVE(#4,(IFCPARAMETERVALUE(0.),#1),(IFCPARAMETERVALUE(1.)),.T.,.PARAMETER.);\n"
+    "#6=IFCPROPERTYSINGLEVALUE('A',$,IFCLABEL('x'),$);\n"
+    "#7=IFCPROPERTYSET('0YvctVUKr0kugbFTf53O9L',$,'Pset',$,(#6,#999));\n"
+    "#8=IFCWALL('1F$7lN9$r5MOA_lpAoNM52',$,$,$,$,$,$,$,$);\n"
+    "#9=IFCRELDEFINESBYPROPERTIES('2F$7lN9$r5MOA_lpAoNM53',$,$,$,(#8),#7);\n"
+    "#10=IFCBSPLINESURFACEWITHKNOTS(1,1,((#1,#2),(#3,#999)),.UNSPECIFIED.,.F.,.F.,.U.,(2,2),(2,2),(0.,1.),(0.,1.),.UNSPECIFIED.);\n"
+    "#11=IFCRELAGGREGATES('3F$7lN9$r5MOA_lpAoNM54',$,$,$,#999,(#8));\n"
+    "ENDSEC;\n"
+    "END-ISO-10303-21;\n";
+}
+
+TEST_CASE("References are resolved in place: scalars, lists, nested lists, mixed selects and missing names", "[ifcparse]") {
+    std::string data(reference_resolution_spf);
+    ifcopenshell::file file(data.data(), (int)data.size());
+    REQUIRE(file.good());
+
+    const std::vector<express::base> points = file.instance_by_id(4).get_attribute_value(0);
+    REQUIRE(points.size() == 3);
+    CHECK(points[0].id() == 1);
+    CHECK(points[2].id() == 3);
+
+    // A select-typed list mixing an inline typed value with a reference.
+    const std::vector<express::base> trim1 = file.instance_by_id(5).get_attribute_value(1);
+    REQUIRE(trim1.size() == 2);
+    CHECK(trim1[0].declaration().name() == "IfcParameterValue");
+    CHECK(trim1[1].id() == 1);
+    const std::vector<express::base> trim2 = file.instance_by_id(5).get_attribute_value(2);
+    REQUIRE(trim2.size() == 1);
+    CHECK(trim2[0].declaration().name() == "IfcParameterValue");
+
+    // A missing name is dropped from a list and nulls a scalar.
+    const std::vector<express::base> properties = file.instance_by_id(7).get_attribute_value(4);
+    REQUIRE(properties.size() == 1);
+    CHECK(properties[0].id() == 6);
+    CHECK(file.instance_by_id(11).get_attribute_value(4).isNull());
+    const std::vector<express::base> related = file.instance_by_id(11).get_attribute_value(5);
+    REQUIRE(related.size() == 1);
+    CHECK(related[0].id() == 8);
+
+    const express::base definition = file.instance_by_id(9).get_attribute_value(5);
+    REQUIRE(definition);
+    CHECK(definition.id() == 7);
+
+    const std::vector<std::vector<express::base>> control_points = file.instance_by_id(10).get_attribute_value(2);
+    REQUIRE(control_points.size() == 2);
+    REQUIRE(control_points[0].size() == 2);
+    CHECK(control_points[0][1].id() == 2);
+    REQUIRE(control_points[1].size() == 1);
+    CHECK(control_points[1][0].id() == 3);
+
+    // Inverses were registered for every reference, resolved or not.
+    CHECK(file.instances_by_reference(1).size() == 3);
+    CHECK(file.instances_by_reference(8).size() == 2);
+}
+
+TEST_CASE("References to bypassed instances are dropped from slots and from mixed lists", "[ifcparse]") {
+    const auto path = std::filesystem::temp_directory_path() / "ifcopenshell_reference_resolution_test.ifc";
+    {
+        std::ofstream out(path);
+        out << reference_resolution_spf;
+    }
+    ifcopenshell::file file(ifcopenshell::uninitialized_tag{});
+    file.bypass_type("IfcCartesianPoint");
+    REQUIRE(file.initialize(path.string()));
+    std::filesystem::remove(path);
+
+    const std::vector<express::base> points = file.instance_by_id(4).get_attribute_value(0);
+    CHECK(points.empty());
+    const std::vector<express::base> trim1 = file.instance_by_id(5).get_attribute_value(1);
+    REQUIRE(trim1.size() == 1);
+    CHECK(trim1[0].declaration().name() == "IfcParameterValue");
+    const std::vector<std::vector<express::base>> control_points = file.instance_by_id(10).get_attribute_value(2);
+    REQUIRE(control_points.size() == 2);
+    CHECK(control_points[0].empty());
+    CHECK(control_points[1].empty());
+}