Fix builds using the system expat library (#1458)

Author: bcoconni

.github/workflows/cpp-python-build.yml

@@ -309,6 +309,7 @@ jobs:
       fail-fast: false
       matrix:
         shared_libs: [ON, OFF]
+        expat: [ON, OFF]
     steps:
       - name: Checkout JSBSim
         uses: actions/checkout@v6
@@ -327,6 +328,9 @@ jobs:
           python-version: '3.10'
       - name: Install Python packages
         run: pip install -r python/requirements.txt
+      - name: Install Expat
+        if: matrix.expat == 'ON'
+        run:  vcpkg install expat
       - name: Checkout CxxTest
         uses: actions/checkout@v6
         with:
@@ -353,7 +357,7 @@ jobs:
         run: |
           New-Item -Path .\build -ItemType Directory -Force
           cd build
-          cmake -DCMAKE_INCLUDE_PATH="$(get-location)\..\cxxtest" -DCMAKE_PREFIX_PATH="$(get-location)\..\backward-cpp" -DBUILD_SHARED_LIBS=${{matrix.shared_libs}} -DFPECTL_DISPLAY_STACK_TRACE=ON -DSTACK_DETAILS_AUTO_DETECT=FALSE ..
+          cmake -DCMAKE_INCLUDE_PATH="$(get-location)\..\cxxtest" -DCMAKE_PREFIX_PATH="$(get-location)\..\backward-cpp" -DBUILD_SHARED_LIBS=${{matrix.shared_libs}} -DSYSTEM_EXPAT=${{matrix.expat}} -DFPECTL_DISPLAY_STACK_TRACE=ON -DSTACK_DETAILS_AUTO_DETECT=FALSE -DCMAKE_TOOLCHAIN_FILE=C:\vcpkg\scripts\buildsystems\vcpkg.cmake ..
       - name: Build JSBSim
         working-directory: build
         run: cmake --build . --config RelWithDebInfo --parallel $Env:NUMBER_OF_PROCESSORS

CMakeLists.txt

@@ -16,9 +16,6 @@ set(LIBRARY_VERSION ${PROJECT_VERSION})
 set(LIBRARY_SOVERSION ${PROJECT_VERSION_MAJOR})
 
 option(SYSTEM_EXPAT "Set to ON to build JSBSim using the system libExpat" OFF)
-if (SYSTEM_EXPAT)
-  find_package(EXPAT)
-endif()
 
 function(get_tail INPUT_STRING OUTPUT_STRING SEPARATOR)
   string(REPLACE ${SEPARATOR} " " TEMP_LIST ${INPUT_STRING})
@@ -134,7 +131,7 @@ endif(CXXTEST_FOUND)
 # Packaging                                                                    #
 ################################################################################
 
-if (PKG_CONFIG_FOUND)
+if (PkgConfig_FOUND)
   if (NOT BUILD_SHARED_LIBS)
     get_target_property(libJSBSim_LINK_LIBRARIES libJSBSim LINK_LIBRARIES)
     foreach(_LIB ${libJSBSim_LINK_LIBRARIES})

src/CMakeLists.txt

@@ -33,39 +33,31 @@ set(HEADERS FGFDMExec.h
 set(SOURCES FGFDMExec.cpp
             FGJSBBase.cpp)
 
-add_library(libJSBSim ${SOURCES}
-  $<TARGET_OBJECTS:Init>
-  $<TARGET_OBJECTS:Atmosphere>
-  $<TARGET_OBJECTS:FlightControl>
-  $<TARGET_OBJECTS:Propulsion>
-  $<TARGET_OBJECTS:Models>
-  $<TARGET_OBJECTS:Math>
-  $<TARGET_OBJECTS:InputOutput>
-  $<TARGET_OBJECTS:Properties>
-  $<TARGET_OBJECTS:Xml>
-  $<TARGET_OBJECTS:Magvar>
-  $<TARGET_OBJECTS:Misc>
-  $<TARGET_OBJECTS:IOStreams>
-  $<TARGET_OBJECTS:GeographicLib>
-  )
+set(OBJECT_LIBS Atmosphere
+                FlightControl
+                GeographicLib
+                Init
+                InputOutput
+                IOStreams
+                Magvar
+                Math
+                Misc
+                Models
+                Properties
+                Propulsion
+                Xml)
+
+add_library(libJSBSim ${SOURCES})
+target_link_libraries(libJSBSim PRIVATE ${OBJECT_LIBS})
 
 target_compile_definitions(libJSBSim PUBLIC
                            JSBSIM_VERSION="${PROJECT_VERSION}${VERSION_MESSAGE}")
 target_include_directories(libJSBSim PUBLIC
                            $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
 
-if(EXPAT_FOUND)
-  target_include_directories(libJSBSim PRIVATE ${EXPAT_INCLUDE_DIRS})
-  if (PKG_CONFIG_FOUND)
-    target_link_libraries(libJSBSim ${PC_EXPAT_LIBRARIES})
-  else()
-    target_link_libraries(libJSBSim ${EXPAT_LIBRARIES})
-  endif()
-endif(EXPAT_FOUND)
-
 if(WIN32)
   target_compile_definitions(libJSBSim PUBLIC _USE_MATH_DEFINES)
-  target_link_libraries(libJSBSim wsock32 ws2_32)
+  target_link_libraries(libJSBSim PUBLIC wsock32 ws2_32)
 
   if(BUILD_SHARED_LIBS)
     set(JSBSIM_LIBRARY_TYPE JSBSIM_EXPORT)
@@ -78,14 +70,11 @@ if(WIN32)
     target_compile_definitions(libJSBSim PUBLIC JSBSIM_STATIC_LINK)
   endif(BUILD_SHARED_LIBS)
 
-  get_target_property(libJSBSim_SOURCE_FILES libJSBSim SOURCES)
-  foreach(OBJECT ${libJSBSim_SOURCE_FILES})
-    if (${OBJECT} MATCHES "TARGET_OBJECTS:([^ >]+)")
-      target_compile_definitions(${CMAKE_MATCH_1} PRIVATE ${JSBSIM_LIBRARY_TYPE})
-    endif()
+  foreach(OBJECT ${OBJECT_LIBS})
+    target_compile_definitions(${OBJECT} PRIVATE ${JSBSIM_LIBRARY_TYPE})
   endforeach(OBJECT)
 elseif(UNIX)
-  target_link_libraries(libJSBSim m)
+  target_link_libraries(libJSBSim PUBLIC m)
 endif(WIN32)
 
 set_target_properties(libJSBSim PROPERTIES

src/simgear/xml/CMakeLists.txt

@@ -1,7 +1,7 @@
 set(SOURCES easyxml.cxx)
 set(HEADERS easyxml.hxx)
 
-if(NOT EXPAT_FOUND)
+if(NOT SYSTEM_EXPAT)
   list(APPEND SOURCES xmlparse.c
                       xmltok.c
                       xmlrole.c)
@@ -25,12 +25,20 @@ if(NOT EXPAT_FOUND)
                       siphash.h)
   set_property(SOURCE xmltok_impl.c PROPERTY HEADER_FILE_ONLY)
   set_property(SOURCE xmltok_ns.c PROPERTY HEADER_FILE_ONLY)
-endif(NOT EXPAT_FOUND)
+endif(NOT SYSTEM_EXPAT)
 
 add_library(Xml OBJECT ${SOURCES})
-target_include_directories(Xml PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
 
-if(WIN32 AND NOT EXPAT_FOUND)
+if(SYSTEM_EXPAT)
+  target_compile_definitions(Xml PRIVATE SYSTEM_EXPAT)
+  if (PkgConfig_FOUND)
+    pkg_check_modules(PC_EXPAT IMPORTED_TARGET expat)
+    target_link_libraries(Xml PkgConfig::PC_EXPAT)
+  else()
+    find_package(EXPAT)
+    target_link_libraries(Xml EXPAT::EXPAT)
+  endif()
+elseif(WIN32)
   target_compile_definitions(Xml PRIVATE XML_STATIC)
 endif()
 

src/simgear/xml/easyxml.cxx

@@ -14,18 +14,19 @@
 INCLUDES
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
-#include "../compiler.h"
-
 #include <string.h>
-
-#include "easyxml.hxx"
-#include "expat.h"
-
 #include <fstream>
 #include <iostream>
 #include <sstream>
 
-#include "FGJSBBase.h"
+#ifdef SYSTEM_EXPAT
+#include <expat.h>
+#else
+#include "expat.h"
+#endif
+
+#include "../compiler.h"
+#include "easyxml.hxx"
 #include "input_output/FGLog.h"
 
 using std::istream;