Another round of CMake improvements

CMakeLists.txt

@@ -7,6 +7,11 @@ project(QWebdav
   LANGUAGES CXX
 )
 
+# By default, look for and support both versions of Qt, but they
+# can be individually turned off with e.g. -DENABLE_QT5=OFF
+option(ENABLE_QT5 "Search for Qt5 libraries and build ${PROJECT_NAME} for Qt5 if found" ON)
+option(ENABLE_QT6 "Search for Qt6 libraries and build ${PROJECT_NAME} for Qt6 if found" ON)
+
 ### Find ECM up-front and complain otherwise
 #
 #
@@ -37,19 +42,29 @@ include(CMakePackageConfigHelpers)
 set(QT_NO_CREATE_VERSIONLESS_TARGETS ON)
 set(QT5_REQUIRED_VERSION 5.15.0)
 set(QT6_REQUIRED_VERSION 6.5.0)
-find_package(Qt6 ${QT6_REQUIRED_VERSION} CONFIG COMPONENTS Core Network Xml)
-find_package(Qt5 ${QT5_REQUIRED_VERSION} CONFIG COMPONENTS Core Network Xml)
+if(ENABLE_QT6)
+  find_package(Qt6 ${QT6_REQUIRED_VERSION} CONFIG COMPONENTS Core Network Xml)
+endif()
+if(ENABLE_QT5)
+  find_package(Qt5 ${QT5_REQUIRED_VERSION} CONFIG COMPONENTS Core Network Xml)
+endif()
 
 set(WITH_QT5 FALSE) # Used when creating the Config.cmake file
 set(WITH_QT6 FALSE)
-if(TARGET Qt5::Core)
+if(ENABLE_QT5 AND TARGET Qt5::Core)
   message(STATUS "Building Qt5 version of ${PROJECT_NAME}")
   set(WITH_QT5 TRUE)
 endif()
-if(TARGET Qt6::Core)
+if(ENABLE_QT5 AND NOT TARGET Qt5::Core)
+  message(STATUS "Qt5 enabled but not found.")
+endif()
+if(ENABLE_QT6 AND TARGET Qt6::Core)
   message(STATUS "Building Qt6 version of ${PROJECT_NAME}")
   set(WITH_QT6 TRUE)
 endif()
+if(ENABLE_QT6 AND NOT TARGET Qt6::Core)
+  message(STATUS "Qt6 enabled but not found.")
+endif()
 if(NOT TARGET Qt5::Core AND NOT TARGET Qt6::Core)
   # If neither is found, complain about Qt5 because then the
   # error message says ">= 5.15.0" which reads most naturally.
@@ -61,49 +76,25 @@ if(NOT TARGET Qt5::Core AND NOT TARGET Qt6::Core)
   )
 endif()
 
+feature_summary(WHAT REQUIRED_PACKAGES_NOT_FOUND FATAL_ON_MISSING_REQUIRED_PACKAGES)
+
 ### QWebdav version header is independent of build type
 #
-#
+# Generate one copy in the top-level, this is installed to
+# multiple locations (per-Qt-version)
 ecm_setup_version(${PROJECT_VERSION}
   VARIABLE_PREFIX QWebdav
-  VERSION_HEADER "${CMAKE_CURRENT_BINARY_DIR}/qwebdav_version.h"
-  PACKAGE_VERSION_FILE "${CMAKE_CURRENT_BINARY_DIR}/QWebdavConfigVersion.cmake"
+  VERSION_HEADER "${CMAKE_BINARY_DIR}/qwebdav_version.h"
+  PACKAGE_VERSION_FILE "${CMAKE_BINARY_DIR}/QWebdavConfigVersion.cmake"
   SOVERSION 1
 )
-install(
-  FILES
-    "${CMAKE_CURRENT_BINARY_DIR}/qwebdav_version.h"
-  DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/QWebdav
-  COMPONENT devel
-)
 
 ### Build
 #
 #
 add_subdirectory(qwebdavlib)
 add_subdirectory(qwebdavlibExample)
 
-### CMake Configuration Files
-#
-#
-configure_package_config_file(
-  "${CMAKE_CURRENT_SOURCE_DIR}/QWebdavConfig.cmake.in"
-  "${CMAKE_CURRENT_BINARY_DIR}/QWebdavConfig.cmake"
-  INSTALL_DESTINATION ${KDE_INSTALL_CMAKEPACKAGEDIR}/QWebdav
-)
-install(
-  FILES
-    "${CMAKE_CURRENT_BINARY_DIR}/QWebdavConfig.cmake"
-    "${CMAKE_CURRENT_BINARY_DIR}/QWebdavConfigVersion.cmake"
-  DESTINATION "${KDE_INSTALL_CMAKEPACKAGEDIR}/QWebdav"
-  COMPONENT devel
-)
-install(
-  EXPORT QWebdavTargets
-  DESTINATION "${KDE_INSTALL_CMAKEPACKAGEDIR}/QWebdav"
-  FILE QWebdavTargets.cmake
-)
-
 ### PackageConfig files
 #
 # These are slightly different from the qmake-produced

qwebdavlib/CMakeLists.txt

@@ -47,34 +47,69 @@ function(add_qwebdav_library QT_VERSION)
 
   install(
     TARGETS qwebdav-qt${QT_VERSION}
-    EXPORT QWebdavTargets
+    EXPORT QWebdav${QT_VERSION}Targets
     ${KDE_INSTALL_TARGETS_DEFAULT_ARGS}
   )
+
+  generate_export_header(qwebdav-qt${QT_VERSION})
+
+  # One copy of the headers per Qt-version, even though they are
+  # identical: this is so that you can build packages of Qt5 and Qt6
+  # libraries separately and they won't collide over the headers.
+  set(_includedir ${KDE_INSTALL_INCLUDEDIR}/qt${QT_VERSION}/qwebdav-qt${QT_VERSION})
+  install(
+    FILES
+      # Generated export-header isn't used (qwebdav_global contains similar
+      # definitions) and the naturalsort header is for internal use.
+      #
+      # ${CMAKE_CURRENT_BINARY_DIR}/qwebdav_export.h
+      # qnaturalsort.h
+      qwebdav.h
+      qwebdav_global.h
+      qwebdavdirparser.h
+      qwebdavitem.h
+    DESTINATION ${_includedir}
+    COMPONENT devel
+  )
+  install(
+    FILES
+      "${CMAKE_BINARY_DIR}/qwebdav_version.h"
+    DESTINATION ${_includedir}
+    COMPONENT devel
+  )
+
+  ### CMake Configuration Files
+  #
+  #
+  configure_package_config_file(
+    "${CMAKE_SOURCE_DIR}/QWebdavConfig.cmake.in"
+    "${CMAKE_CURRENT_BINARY_DIR}/QWebdav${QT_VERSION}Config.cmake"
+    INSTALL_DESTINATION ${KDE_INSTALL_CMAKEPACKAGEDIR}/QWebdav${QT_VERSION}
+  )
+  install(
+    FILES
+      "${CMAKE_CURRENT_BINARY_DIR}/QWebdav${QT_VERSION}Config.cmake"
+    DESTINATION "${KDE_INSTALL_CMAKEPACKAGEDIR}/QWebdav${QT_VERSION}"
+    COMPONENT devel
+  )
+  install(
+    FILES
+      "${CMAKE_BINARY_DIR}/QWebdavConfigVersion.cmake"
+    RENAME
+      "QWebdav${QT_VERSION}ConfigVersion.cmake"
+    DESTINATION "${KDE_INSTALL_CMAKEPACKAGEDIR}/QWebdav${QT_VERSION}"
+    COMPONENT devel
+  )
+  install(
+    EXPORT QWebdav${QT_VERSION}Targets
+    DESTINATION "${KDE_INSTALL_CMAKEPACKAGEDIR}/QWebdav${QT_VERSION}"
+    FILE QWebdav${QT_VERSION}Targets.cmake
+  )
 endfunction()
 
 if(WITH_QT5)
   add_qwebdav_library(5)
-  add_library(QWebdav ALIAS qwebdav-qt5)
 endif()
 if(WITH_QT6)
   add_qwebdav_library(6)
-  if(NOT TARGET QWebdav)
-    add_library(QWebdav ALIAS qwebdav-qt6)
-  endif()
 endif()
-
-# Only one export header, regardless of which libraries are built
-generate_export_header(QWebdav)
-
-# Only one copy of the headers, regardless of which libraries are built
-install(
-  FILES
-    ${CMAKE_CURRENT_BINARY_DIR}/qwebdav_export.h
-    qnaturalsort.h
-    qwebdav.h
-    qwebdav_global.h
-    qwebdavdirparser.h
-    qwebdavitem.h
-  DESTINATION ${KDE_INSTALL_INCLUDEDIR}/QWebdav
-  COMPONENT devel
-)

qwebdavlibExample/CMakeLists.txt

@@ -13,8 +13,15 @@ project(QWebdavExample
 set(CMAKE_AUTOMOC ON)
 
 # If we're building as part of the QWebDAV top-level build, we already
-# have the target QWebdav available. In that case, do only the CMake-
-# based build.
+# have a QWebdav target available -- prefer Qt6, and give it an alias.
+
+if(TARGET qwebdav-qt6)
+  add_library(QWebdav ALIAS qwebdav-qt6)
+elseif(TARGET qwebdav-qt5)
+  add_library(QWebdav ALIAS qwebdav-qt5)
+endif()
+
+# If we have a QWebdav target, do only the CMake-based build.
 if(NOT TARGET QWebdav)
   # Outside of the QWebDAV top-level build, demonstrate both
   # CMake and pkgconfig approaches.
@@ -28,6 +35,11 @@ if(NOT TARGET QWebdav)
   if(NOT TARGET Qt5::Core AND NOT TARGET Qt6::Core)
     message(FATAL_ERROR "No installed Qt version found.")
   endif()
+  if(TARGET Qt6::Core)
+    set(QT_VERSION 6)
+  else()
+    set(QT_VERSION 5)
+  endif()
 
   find_package(PkgConfig)
   if(PkgConfig_FOUND)
@@ -39,7 +51,7 @@ if(NOT TARGET QWebdav)
     endif()
   endif()
 
-  find_package(QWebdav 1.0) # Works with whatever Qt versions are installed
+  find_package(QWebdav${QT_VERSION} 1.0) # Works with whatever Qt versions are installed
 
   if(NOT TARGET QWebdav AND NOT TARGET PkgConfig::QWebdav)
     message(FATAL_ERROR "No installed QWebDAV found.")