Change libexpat to be included with add_subdirectory()

- Confirmed that libexpat is built statically and linked with xlsxreader
- May need da7cda3a85 for Windows
- Although libexpat's CMake options are all prefixed with LIBEXPAT_, it also adds some cache entries like SIZE_T (from expat/ConfigureChecks.cmake). Unsure if these affect other libs.
- xlsxio may need additional reconfiguration after moving to add_subdirectory() to find libexpat/libzip on non-Linux platforms.

depends/CMakeLists.txt

@@ -35,25 +35,19 @@ endforeach()
 include(ExternalProject)
 
 if(WIN32)
-  set(EXPAT_LIB_NAME_SUFFIX "MD")
   set(XLSXIO_C_FLAGS "${CMAKE_C_FLAGS} /DXML_STATIC")
 else()
-  set(EXPAT_LIB_NAME_SUFFIX "")
   set(XLSXIO_C_FLAGS "${CMAKE_C_FLAGS} -DXML_STATIC")
 endif()
 
-set(LIBEXPAT_INSTALL_DIR ${CMAKE_CURRENT_BINARY_DIR}/libexpat)
-set(LIBEXPAT_LIB ${LIBEXPAT_INSTALL_DIR}/lib/libexpat${EXPAT_LIB_NAME_SUFFIX}${CMAKE_STATIC_LIBRARY_SUFFIX})
-set(LIBEXPAT_LIB ${LIBEXPAT_LIB} PARENT_SCOPE)
-ExternalProject_Add(libexpat_project
-    PREFIX      libexpat
-    SOURCE_DIR  ${CMAKE_CURRENT_SOURCE_DIR}/libexpat/expat
-    INSTALL_DIR ${LIBEXPAT_INSTALL_DIR}
-    BUILD_BYPRODUCTS ${LIBEXPAT_LIB}
-    CMAKE_GENERATOR "${CMAKE_GENERATOR}"
-    CMAKE_GENERATOR_TOOLSET "${CMAKE_GENERATOR_TOOLSET}"
-    CMAKE_ARGS  ${CL_ARGS} -DCMAKE_INSTALL_PREFIX=${LIBEXPAT_INSTALL_DIR} -DCMAKE_BUILD_TYPE=Release -DEXPAT_BUILD_EXAMPLES=OFF -DEXPAT_BUILD_TESTS=OFF -DEXPAT_BUILD_TOOLS=OFF -DEXPAT_SHARED_LIBS=OFF -DCMAKE_INSTALL_LIBDIR=lib -DCMAKE_POSITION_INDEPENDENT_CODE=ON
-)
+# set the default values of libexpat options - the descriptions are left empty
+# because later option() calls *do* override those
+set(EXPAT_BUILD_EXAMPLES OFF CACHE BOOL "")
+set(EXPAT_BUILD_TESTS OFF CACHE BOOL "")
+set(EXPAT_BUILD_TOOLS OFF CACHE BOOL "")
+set(EXPAT_SHARED_LIBS OFF CACHE BOOL "")
+set(EXPAT_BUILD_DOCS OFF CACHE BOOL "")
+add_subdirectory(libexpat/expat)
 
 set(LIBZIP_INSTALL_DIR ${CMAKE_CURRENT_BINARY_DIR}/libzip)
 set(LIBZIP_LIB ${LIBZIP_INSTALL_DIR}/lib/${CMAKE_STATIC_LIBRARY_PREFIX}zip${CMAKE_STATIC_LIBRARY_SUFFIX})
@@ -74,11 +68,11 @@ set(XLSXIO_LIB ${XLSXIO_INSTALL_DIR}/lib/${CMAKE_STATIC_LIBRARY_PREFIX}xlsxio_re
 set(XLSXIO_LIB ${XLSXIO_LIB} PARENT_SCOPE)
 ExternalProject_Add(xlsxio_project
     PREFIX      xlsxio
-    DEPENDS     libexpat_project libzip_project
+    DEPENDS     libzip_project
     SOURCE_DIR  ${CMAKE_CURRENT_SOURCE_DIR}/xlsxio
     INSTALL_DIR ${XLSXIO_INSTALL_DIR}
     BUILD_BYPRODUCTS ${XLSXIO_LIB}
     CMAKE_GENERATOR "${CMAKE_GENERATOR}"
     CMAKE_GENERATOR_TOOLSET "${CMAKE_GENERATOR_TOOLSET}"
-    CMAKE_ARGS  ${CL_ARGS} -DCMAKE_INSTALL_PREFIX=${XLSXIO_INSTALL_DIR} -DCMAKE_BUILD_TYPE=Release -DBUILD_STATIC=ON -DBUILD_SHARED=OFF -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DBUILD_TOOLS=OFF -DBUILD_EXAMPLES=OFF -DBUILD_DOCUMENTATION=OFF -DWITH_LIBZIP=ON -DZLIB_DIR=${ZLIB_DIR} -DLIBZIP_DIR=${LIBZIP_INSTALL_DIR} -DEXPAT_DIR=${LIBEXPAT_INSTALL_DIR} -DEXPAT_LIBRARIES=${LIBEXPAT_LIB} -DEXPAT_INCLUDE_DIRS=${LIBEXPAT_INSTALL_DIR}/include -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DCMAKE_C_FLAGS=${XLSXIO_C_FLAGS}
+    CMAKE_ARGS  ${CL_ARGS} -DCMAKE_INSTALL_PREFIX=${XLSXIO_INSTALL_DIR} -DCMAKE_BUILD_TYPE=Release -DBUILD_STATIC=ON -DBUILD_SHARED=OFF -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DBUILD_TOOLS=OFF -DBUILD_EXAMPLES=OFF -DBUILD_DOCUMENTATION=OFF -DWITH_LIBZIP=ON -DZLIB_DIR=${ZLIB_DIR} -DLIBZIP_DIR=${LIBZIP_INSTALL_DIR} -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DCMAKE_C_FLAGS=${XLSXIO_C_FLAGS}
 )

plugins/CMakeLists.txt

@@ -82,8 +82,6 @@ add_library(xlsxio_read STATIC IMPORTED)
 set_target_properties(xlsxio_read PROPERTIES IMPORTED_LOCATION ${XLSXIO_LIB})
 add_library(zip STATIC IMPORTED)
 set_target_properties(zip PROPERTIES IMPORTED_LOCATION ${LIBZIP_LIB})
-add_library(expat STATIC IMPORTED)
-set_target_properties(expat PROPERTIES IMPORTED_LOCATION ${LIBEXPAT_LIB})
 
 if(WIN32)
   set(LIB_Z_LIB "depends/zlib/lib/zlib")