refactor: extract src/ifcutil/ from src/ifcviewer/ (Unit, Geolocation, Placement)

Unit / Geolocation / Placement are schema-agnostic IFC helpers ported
from ifcopenshell.util.{unit,geolocation,placement}. Nothing about
them is viewer-specific: pure IfcParse + Eigen, no Qt, no IfcGeom, no
renderer. Living under src/ifcviewer/ implies an unwanted dependency
direction every time a non-viewer caller (test_federation, the bonsai
SettingsView georef readout, a future standalone IFC tool) wants to
use them.

Move them to a new `src/ifcutil/` static lib (IfcUtil). The lib has
PUBLIC `target_include_directories(${CMAKE_CURRENT_SOURCE_DIR})` so
callers that link IfcUtil can keep `#include "Unit.h"` etc. without
relative-path adjustments — the include dir propagates transitively
via IfcViewer's PUBLIC link.

## Changes

* `git mv src/ifcviewer/{Geolocation,Placement,Unit}.{h,cpp}
   → src/ifcutil/` (history follows the rename).
* `src/ifcutil/CMakeLists.txt`: IfcUtil static lib, PUBLIC links
  IfcParse + Eigen3::Eigen, PUBLIC include dir.
* `cmake/CMakeLists.txt`: `add_subdirectory(../src/ifcutil ifcutil)`
  before ifcviewer/ so the link target exists when IfcViewer's
  CMakeLists runs.
* `src/ifcviewer/CMakeLists.txt`: IfcUtil added to IfcViewer's PUBLIC
  link_libraries.
* `src/ifcviewer/tests/CMakeLists.txt`: test_federation drops the
  explicit `${IFCVIEWER_SRC}/{Unit,Geolocation,Placement}.cpp`
  source list and links `IfcUtil` instead (matches how production
  code resolves the symbols).
* `src/bonsaiviewer/modules/models/SettingsView.cpp`: the two
  explicit `#include "../../../ifcviewer/{Geolocation,Unit}.h"`
  paths swap to `../../../ifcutil/…`. All other callers use bare
  `#include "Unit.h"` style and continue to work via the propagated
  include dir.

## Verification

* `ninja -C build-viewer` builds clean: IfcUtil + IfcViewer +
  IfcViewerMinimal + BonsaiViewer + all four pre-existing
  ifcviewer tests + the two from-wgpu tests.
* `test_federation` runs green: 226 assertions in 22 test cases
  pass with IfcUtil linked instead of the explicit-source compile.
* `git log --follow` traces e.g. `Geolocation.cpp` back through the
  rename to its prior location in src/ifcviewer/.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

cmake/CMakeLists.txt

@@ -700,6 +700,11 @@ if(BUILD_BONSAIVIEWER_TESTS)
 endif()
 
 if(BUILD_BONSAIVIEWER)
+    # IfcUtil first — schema-agnostic helpers (Unit, Geolocation,
+    # Placement) that IfcViewer's Federation links against. Adding here
+    # before ifcviewer/ so the link target exists when IfcViewer's
+    # CMakeLists runs.
+    add_subdirectory(../src/ifcutil ifcutil)
     # IfcViewer is the unified scene + render lib since the wgpu/ifcviewer
     # merge — wgpu-native is fetched inside its CMakeLists.txt.
     add_subdirectory(../src/ifcviewer ifcviewer)

src/bonsaiviewer/modules/models/SettingsView.cpp

@@ -23,9 +23,9 @@
 
 #include "../../SessionState.h"
 #include "../../../ifcviewer/Federation.h"
-#include "../../../ifcviewer/Geolocation.h"
+#include "../../../ifcutil/Geolocation.h"
 #include "../../../ifcviewer/SceneLoader.h"
-#include "../../../ifcviewer/Unit.h"
+#include "../../../ifcutil/Unit.h"
 
 #include <cmath>
 

src/ifcutil/CMakeLists.txt

@@ -0,0 +1,60 @@
+################################################################################
+#                                                                              #
+# This file is part of IfcOpenShell.                                           #
+#                                                                              #
+# IfcOpenShell is free software: you can redistribute it and/or modify         #
+# it under the terms of the Lesser GNU General Public License as published by  #
+# the Free Software Foundation, either version 3.0 of the License, or          #
+# (at your option) any later version.                                          #
+#                                                                              #
+# IfcOpenShell is distributed in the hope that it will be useful,              #
+# but WITHOUT ANY WARRANTY; without even the implied warranty of               #
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the                 #
+# Lesser GNU General Public License for more details.                          #
+#                                                                              #
+# You should have received a copy of the Lesser GNU General Public License     #
+# along with this program. If not, see <http://www.gnu.org/licenses/>.         #
+#                                                                              #
+################################################################################
+
+message("Running CMakeLists.txt in /src/ifcutil")
+
+# Schema-agnostic IFC helpers ported from ifcopenshell.util.*. Pure
+# IfcParse + Eigen, no Qt, no IfcGeom, no viewer/renderer deps — so unit
+# tests and standalone IFC tools can pull them in without dragging
+# OpenCASCADE or Qt6 into the link.
+#
+# Currently:
+#   * Unit        — unit conversions (ifcopenshell.util.unit)
+#   * Geolocation — IfcMapConversion / WCS / helmert helpers
+#                   (ifcopenshell.util.geolocation)
+#   * Placement   — IfcLocalPlacement / IfcAxis2Placement reduction
+#                   (ifcopenshell.util.placement)
+
+find_package(Eigen3 REQUIRED)
+
+file(GLOB IFCUTIL_CPP_FILES ${CMAKE_CURRENT_SOURCE_DIR}/*.cpp)
+file(GLOB IFCUTIL_H_FILES   ${CMAKE_CURRENT_SOURCE_DIR}/*.h)
+
+add_library(IfcUtil STATIC ${IFCUTIL_CPP_FILES} ${IFCUTIL_H_FILES})
+
+set_target_properties(IfcUtil PROPERTIES
+    VERSION   "${PROJECT_VERSION}"
+    SOVERSION "${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}"
+)
+
+# PUBLIC: callers (IfcViewer, test_federation, future tools) get
+# `#include "Unit.h"` etc. via this directory automatically, no
+# `#include "../ifcutil/Unit.h"` ugliness at call sites.
+target_include_directories(IfcUtil PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+
+target_link_libraries(IfcUtil PUBLIC
+    IfcParse
+    Eigen3::Eigen
+)
+
+install(TARGETS IfcUtil EXPORT ${IFCOPENSHELL_EXPORT_TARGETS})
+
+install(FILES ${IFCUTIL_H_FILES}
+    DESTINATION ${INCLUDEDIR}/ifcutil
+)

src/ifcviewer/CMakeLists.txt

@@ -140,6 +140,7 @@ target_include_directories(IfcViewer PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
 add_dependencies(IfcViewer ${kernel_libraries} ${mapping_libraries})
 
 target_link_libraries(IfcViewer PUBLIC
+    IfcUtil
     IfcGeom
     IfcParse
     ${OpenCASCADE_LIBRARIES}

src/ifcviewer/tests/CMakeLists.txt

@@ -66,15 +66,6 @@ find_package(Eigen3 REQUIRED)
 add_executable(test_federation
     test_federation.cpp
     ${IFCVIEWER_SRC}/Federation.cpp
-    # Federation pulls in Unit::convert for federationUnitToMeters and
-    # Geolocation helpers (helmertMetersFromParameters, getWcs, getMapUnit)
-    # for computeModelGeoref; compile both directly so the test doesn't
-    # have to link the whole IfcViewer library (which would drag in
-    # Qt6::OpenGL, OpenCASCADE, etc.).  Placement.cpp provides
-    # getAxis2Placement, called from Geolocation::getWcs.
-    ${IFCVIEWER_SRC}/Unit.cpp
-    ${IFCVIEWER_SRC}/Geolocation.cpp
-    ${IFCVIEWER_SRC}/Placement.cpp
 )
 set_target_properties(test_federation PROPERTIES AUTOMOC ON)
 target_include_directories(test_federation PRIVATE ${IFCVIEWER_SRC})
@@ -84,6 +75,11 @@ target_link_libraries(test_federation PRIVATE
     Qt${QT_VERSION}::Gui    # Federation::HomeView uses QVector3D from QtGui
     Qt${QT_VERSION}::Test   # QSignalSpy
     Eigen3::Eigen           # Federation.h: composed matrices use Eigen
-    IfcParse                # Unit.cpp uses express::Base / file APIs
+    # IfcUtil provides Unit::convert + Geolocation helpers
+    # (helmertMetersFromParameters, getWcs, getMapUnit) + Placement
+    # (getAxis2Placement, called from Geolocation::getWcs). Linking the
+    # static lib avoids re-compiling those .cpp files here and pulls
+    # the IfcUtil include dir + IfcParse transitively.
+    IfcUtil
 )
 catch_discover_tests(test_federation)