Increase CMake minimum version from 3.9 to 3.16

CMakeLists.txt

@@ -9,7 +9,7 @@
 ################################################################################
 # General settings
 ################################################################################
-cmake_minimum_required(VERSION 3.9 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.16)
 
 project(PROJ
   DESCRIPTION "PROJ coordinate transformation software library"
@@ -219,16 +219,6 @@ if(ENABLE_CURL)
   if(CURL_FOUND)
     set(CURL_ENABLED TRUE)
 
-    # Target CURL::libcurl only defined since CMake 3.12
-    # TODO: remove this when CMake >= 3.12 required
-    if(NOT TARGET CURL::libcurl)
-      add_library(CURL::libcurl INTERFACE IMPORTED)
-      set_target_properties(CURL::libcurl PROPERTIES
-        INTERFACE_INCLUDE_DIRECTORIES "${CURL_INCLUDE_DIRS}"
-        INTERFACE_LINK_LIBRARIES      "${CURL_LIBRARIES}"
-      )
-    endif()
-
     # Curl SSL options are described in
     #   https://curl.se/libcurl/c/CURLOPT_SSL_OPTIONS.html
     #set(CURLSSLOPT_NO_REVOKE 2)

cmake/Ccache.cmake

@@ -7,8 +7,6 @@
 # Add "include(Ccache)" to CMakeLists.txt and enable
 # using the option -D USE_CCACHE=ON
 
-cmake_minimum_required(VERSION 3.9)
-
 
 option(USE_CCACHE
   "Use ccache (or clcache for MSVC) to compile C/C++ objects" OFF)

cmake/ProjUtilities.cmake

@@ -116,9 +116,10 @@ function(configure_proj_pc)
   if(HAVE_LIBDL)
     list(APPEND EXTRA_LIBS -ldl)
   endif()
-  # Join list with a space; list(JOIN) added CMake 3.12
-  string(REPLACE ";" " " EXTRA_LIBS "${EXTRA_LIBS}")
-  string(REPLACE ";" " " EXTRA_REQUIRES "${EXTRA_REQUIRES}")
+
+  # Join lists with a space
+  list(JOIN EXTRA_LIBS " " EXTRA_LIBS)
+  list(JOIN EXTRA_REQUIRES " " EXTRA_REQUIRES)
 
   configure_file(
     ${CMAKE_CURRENT_SOURCE_DIR}/proj.pc.in

src/lib_proj.cmake

@@ -258,19 +258,22 @@ set(SRC_LIBPROJ_CORE
   ${CMAKE_CURRENT_BINARY_DIR}/proj_config.h
 )
 
-if (CMAKE_VERSION VERSION_GREATER_EQUAL 3.16)
-  set_property(SOURCE list.cpp # because if sets DO_NOT_DEFINE_PROJ_HEAD
-                      transformations/defmodel.cpp # Evaluator class conflict
-                      transformations/tinshift.cpp # Evaluator class conflict
-                      wkt1_parser.cpp
-                      wkt2_parser.cpp
-                      wkt1_generated_parser.c
-                      wkt2_generated_parser.c
-               PROPERTY SKIP_UNITY_BUILD_INCLUSION ON)
-  if(WIN32)
-      set_property(SOURCE networkfilemanager.cpp PROPERTY SKIP_UNITY_BUILD_INCLUSION ON)
-  endif()
-endif ()
+# Skip Unity build for specific files
+set(SKIP_UNITY_BUILD_FILES
+  list.cpp # because if sets DO_NOT_DEFINE_PROJ_HEAD
+  transformations/defmodel.cpp # Evaluator class conflict
+  transformations/tinshift.cpp # Evaluator class conflict
+  wkt1_parser.cpp
+  wkt2_parser.cpp
+  wkt1_generated_parser.c
+  wkt2_generated_parser.c
+)
+if(WIN32)
+  list(APPEND SKIP_UNITY_BUILD_FILES
+    networkfilemanager.cpp
+  )
+endif()
+set_property(SOURCE ${SKIP_UNITY_BUILD_FILES} PROPERTY SKIP_UNITY_BUILD_INCLUSION ON)
 
 set(HEADERS_LIBPROJ
   proj.h
@@ -470,26 +473,12 @@ endif()
 
 if(TIFF_ENABLED)
   target_compile_definitions(proj PRIVATE -DTIFF_ENABLED)
-  if( CMAKE_VERSION VERSION_LESS 3.11 AND CMAKE_CROSSCOMPILING )
-      # Hack needed for ubuntu:18.04 mingw64 cross compiling to avoid
-      # -isystem to be emitted (similar to https://discourse.cmake.org/t/use-of-isystem/1574)
-      target_include_directories(proj PRIVATE ${TIFF_INCLUDE_DIRS})
-      target_link_libraries(proj PRIVATE ${TIFF_LIBRARIES})
-  else()
-      target_link_libraries(proj PRIVATE TIFF::TIFF)
-  endif()
+  target_link_libraries(proj PRIVATE TIFF::TIFF)
 endif()
 
 if(CURL_ENABLED)
   target_compile_definitions(proj PRIVATE -DCURL_ENABLED)
-  if( CMAKE_VERSION VERSION_LESS 3.11 AND CMAKE_CROSSCOMPILING )
-      # Hack needed for ubuntu:18.04 mingw64 cross compiling to avoid
-      # -isystem to be emitted (similar to https://discourse.cmake.org/t/use-of-isystem/1574)
-      target_include_directories(proj PRIVATE ${CURL_INCLUDE_DIRS})
-      target_link_libraries(proj PRIVATE ${CURL_LIBRARIES})
-  else()
-      target_link_libraries(proj PRIVATE CURL::libcurl)
-  endif()
+  target_link_libraries(proj PRIVATE CURL::libcurl)
   target_link_libraries(proj
     PRIVATE
       $<$<CXX_COMPILER_ID:MSVC>:ws2_32>

test/unit/CMakeLists.txt

@@ -25,49 +25,21 @@ endif()
 
 else()
 
-message(STATUS "Using internal GTest")
+message(STATUS "Fetching GTest")
 
+# Add Google Test
 #
-# Build Google Test
-#
-# Source /~https://github.com/google/googletest/blob/master/googletest/README.md
-# Download and unpack googletest at configure time
-configure_file(
-  ${PROJ_SOURCE_DIR}/test/googletest/CMakeLists.txt.in
-  ${PROJ_BINARY_DIR}/googletest-download/CMakeLists.txt)
-
-if(CYGWIN)
-# needed at least with gcc 11.3.0 Cygwin, otherwise build errors in
-# in googletest-src/googletest/include/gtest/internal/gtest-port.h related to
-# fileno() and other functions, when building gtest or including it
-add_definitions(-D_GNU_SOURCE)
-endif()
+# Source /~https://github.com/google/googletest/blob/main/googletest/README.md
 
-execute_process(COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
-  RESULT_VARIABLE result
-  WORKING_DIRECTORY ${PROJ_BINARY_DIR}/googletest-download)
-if(result)
-  message(FATAL_ERROR "CMake step for googletest failed: ${result}")
-endif()
-execute_process(COMMAND ${CMAKE_COMMAND} --build .
-  RESULT_VARIABLE result
-  WORKING_DIRECTORY ${PROJ_BINARY_DIR}/googletest-download)
-if(result)
-  message(FATAL_ERROR "Build step for googletest failed: ${result}")
-endif()
-# Prevent overriding the parent project's compiler/linker
-# settings on Windows
+include(FetchContent)
+FetchContent_Declare(
+  googletest
+  # Specify the commit you depend on and update it regularly.
+  URL /~https://github.com/google/googletest/archive/5376968f6948923e2411081fd9372e71a59d8e77.zip
+)
+# For Windows: Prevent overriding the parent project's compiler/linker settings
 set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
-# Add googletest directly to our build. This defines
-# the gtest and gtest_main targets.
-option(INSTALL_GTEST "Enable installation of googletest" OFF)
-add_subdirectory(
-  ${PROJ_BINARY_DIR}/googletest-src
-  ${PROJ_BINARY_DIR}/googletest-build
-  EXCLUDE_FROM_ALL)
-
-# Provide the same target name as find_package(GTest)
-add_library(GTest::gtest ALIAS gtest)
+FetchContent_MakeAvailable(googletest)
 
 endif()  # USE_EXTERNAL_GTEST
 
@@ -148,9 +120,7 @@ set(PROJ_TEST_CPP_API_SOURCES
   test_c_api.cpp
   test_grids.cpp)
 add_executable(proj_test_cpp_api ${PROJ_TEST_CPP_API_SOURCES})
-if (CMAKE_VERSION VERSION_GREATER_EQUAL 3.16)
-  set_property(SOURCE ${PROJ_TEST_CPP_API_SOURCES} PROPERTY SKIP_UNITY_BUILD_INCLUSION ON)
-endif ()
+set_property(SOURCE ${PROJ_TEST_CPP_API_SOURCES} PROPERTY SKIP_UNITY_BUILD_INCLUSION ON)
 
 target_link_libraries(proj_test_cpp_api
   PRIVATE GTest::gtest
@@ -182,14 +152,7 @@ add_executable(test_network
   test_network.cpp)
 if(CURL_ENABLED)
   target_compile_definitions(test_network PRIVATE -DCURL_ENABLED)
-  if( CMAKE_VERSION VERSION_LESS 3.11 AND CMAKE_CROSSCOMPILING )
-      # Hack needed for ubuntu:18.04 mingw64 cross compiling to avoid
-      # -isystem to be emitted (similar to https://discourse.cmake.org/t/use-of-isystem/1574)
-      target_include_directories(test_network PRIVATE ${CURL_INCLUDE_DIRS})
-      target_link_libraries(test_network PRIVATE ${CURL_LIBRARIES})
-  else()
-      target_link_libraries(test_network PRIVATE CURL::libcurl)
-  endif()
+  target_link_libraries(test_network PRIVATE CURL::libcurl)
 endif()
 target_link_libraries(test_network
   PRIVATE GTest::gtest