CMake: Raise cmake_minimum_required from 3.12 to 3.15

Remove code that checks CMake versions lower than 3.15

CMake/compatibility.cmake

@@ -1,7 +1,7 @@
 #
 # CMake compatibility functions and macros for the Fast Light Tool Kit (FLTK)
 #
-# Copyright 1998-2021 by Bill Spitzak and others.
+# Copyright 1998-2023 by Bill Spitzak and others.
 #
 # This library is free software. Distribution and use rights are outlined in
 # the file "COPYING" which should have been included with this file.  If this
@@ -16,7 +16,7 @@
 
 ################################################################################
 #
-# The functions (and macros) in this file are defined to simplify CMake
+# The functions and maybe macros in this file are defined to simplify CMake
 # code that uses features not available in all supported CMake versions.
 # Functions should be preferred (rather than macros) because functions
 # have their own variable scope.
@@ -33,6 +33,12 @@
 #
 ################################################################################
 
+
+# Right now we don't need compatibility functions
+# This file is currently "empty" but left for documentation purposes
+# An example function documentation follows...
+
+
 ################################################################################
 #
 # function fl_target_link_directories - add link directories to target
@@ -62,13 +68,3 @@
 #   can be an empty list.
 #
 ################################################################################
-
-function (fl_target_link_directories TARGET SCOPE DIRS)
-
-  if (CMAKE_VERSION VERSION_LESS "3.13")
-    link_directories (${DIRS})
-  else ()
-    target_link_directories (${TARGET} ${SCOPE} ${DIRS})
-  endif ()
-
-endfunction () # fl_target_link_directories()

CMake/fl_create_example.cmake

@@ -125,7 +125,7 @@ function (CREATE_EXAMPLE NAME SOURCES LIBRARIES)
   endif ()
 
   if (FLTK_HAVE_CAIRO AND PKG_CAIRO_LIBRARY_DIRS)
-    fl_target_link_directories (${TARGET_NAME} PUBLIC ${PKG_CAIRO_LIBRARY_DIRS})
+    target_link_directories (${TARGET_NAME} PUBLIC ${PKG_CAIRO_LIBRARY_DIRS})
   endif ()
 
   if (USE_GDIPLUS)        # can only be true on Windows

CMake/options.cmake

@@ -536,7 +536,7 @@ if (OPTION_USE_GL)
     unset(HAVE_GL_GLU_H CACHE)
     find_file (HAVE_GL_GLU_H GL/glu.h PATHS ${X11_INCLUDE_DIR})
   else()
-    include (FindOpenGL)
+    find_package(OpenGL)
     if (APPLE)
       set (HAVE_GL_GLU_H ${HAVE_OPENGL_GLU_H})
     endif (APPLE)

CMake/setup.cmake

@@ -82,11 +82,9 @@ include(TestBigEndian)
 TEST_BIG_ENDIAN(WORDS_BIGENDIAN)
 
 if (CMAKE_GENERATOR MATCHES "Xcode")
-  if (NOT (CMAKE_VERSION VERSION_LESS 3.9)) # CMake 3.9 and up
-    # Tell Xcode to regenerate scheme information automatically whenever the
-    # CMake configuration changes without asking the user
-    set (CMAKE_XCODE_GENERATE_SCHEME 1)
-  endif()
+  # Tell Xcode to regenerate scheme information automatically whenever the
+  # CMake configuration changes without asking the user
+  set (CMAKE_XCODE_GENERATE_SCHEME 1)
 endif()
 
 if (APPLE)

CMakeLists.txt

@@ -25,23 +25,9 @@
 #         at least CMake 3.12.0
 # Note 2: Used in fluid since 05/2023,
 #         used for Windows (MSVC) shared lib builds much earlier
+# Note 3: More modern CMake features require 3.13...3.15 (Nov 2023)
 
-cmake_minimum_required (VERSION 3.12.0 FATAL_ERROR) # 05/2023
-
-#######################################################################
-
-# Use "legacy mode" of FindOpenGL (avoid CMake developer warning).
-# Note: we're using FindOpenGL with `OPENGL_LIBRARIES` and not (yet)
-# the `OpenGL::GL` target. This may be changed in the future.
-# See https://cmake.org/cmake/help/latest/policy/CMP0072.html
-# Update Feb 28, 2021: To avoid a warning about "OLD" policies we set
-# OpenGL_GL_PREFERENCE directly to "LEGACY" (other option: "GLVND").
-
-# if (POLICY CMP0072)
-#   cmake_policy (SET CMP0072 OLD)
-# endif ()
-
-set (OpenGL_GL_PREFERENCE LEGACY)
+cmake_minimum_required (VERSION 3.15.0 FATAL_ERROR)
 
 #######################################################################
 # define the FLTK project and version
@@ -56,7 +42,9 @@ project (FLTK VERSION 1.4.0)
 include (CMake/fl_debug_var.cmake)
 include (CMake/fl_debug_pkg.cmake)
 include (CMake/fl_add_library.cmake)
-include (CMake/compatibility.cmake)
+
+# right now we don't use compatibility functions
+# include (CMake/compatibility.cmake)
 
 if (0)
   fl_debug_var (FLTK_VERSION_MAJOR)

fltk-options/CMakeLists.txt

@@ -53,7 +53,7 @@ endif ()
 
 # we must link fltk-optons with cairo if option CAIRO is enabled
 if (FLTK_HAVE_CAIRO)
-  fl_target_link_directories (fltk-options PRIVATE "${PKG_CAIRO_LIBRARY_DIRS}")
+  target_link_directories (fltk-options PRIVATE ${PKG_CAIRO_LIBRARY_DIRS})
 endif (FLTK_HAVE_CAIRO)
 
 if (USE_GDIPLUS)        # can only be true on Windows
@@ -71,7 +71,7 @@ if (WIN32)
   add_executable (fltk-options-cmd ${CPPFILES} ${HEADERFILES})
   target_link_libraries (fltk-options-cmd ${FLTK_OPTIONS_LIBS})
   if (FLTK_HAVE_CAIRO)
-    fl_target_link_directories (fltk-options-cmd PRIVATE "${PKG_CAIRO_LIBRARY_DIRS}")
+    target_link_directories (fltk-options-cmd PRIVATE ${PKG_CAIRO_LIBRARY_DIRS})
   endif (FLTK_HAVE_CAIRO)
 endif ()
 

fluid/CMakeLists.txt

@@ -168,7 +168,7 @@ endif ()
 if (FLTK_HAVE_CAIRO)
   target_include_directories (fluid PRIVATE ${PKG_CAIRO_INCLUDE_DIRS})
   if (PKG_CAIRO_LIBRARY_DIRS)
-    fl_target_link_directories (fluid PRIVATE ${PKG_CAIRO_LIBRARY_DIRS})
+    target_link_directories (fluid PRIVATE ${PKG_CAIRO_LIBRARY_DIRS})
   endif ()
 endif (FLTK_HAVE_CAIRO)
 
@@ -191,7 +191,7 @@ if (WIN32)
   if (FLTK_HAVE_CAIRO)
     target_include_directories (fluid-cmd PRIVATE ${PKG_CAIRO_INCLUDE_DIRS})
     if (PKG_CAIRO_LIBRARY_DIRS)
-      fl_target_link_directories (fluid-cmd PRIVATE ${PKG_CAIRO_LIBRARY_DIRS})
+      target_link_directories (fluid-cmd PRIVATE ${PKG_CAIRO_LIBRARY_DIRS})
     endif ()
   endif (FLTK_HAVE_CAIRO)
 endif (WIN32)

src/CMakeLists.txt

@@ -644,14 +644,7 @@ if (USE_XFT)
 endif (USE_XFT)
 
 if (UNIX AND OPTION_USE_WAYLAND)
-  if (NOT (CMAKE_VERSION VERSION_LESS 3.4))
-    pkg_get_variable(PROTOCOLS wayland-protocols pkgdatadir) # requires cmake 3.4
-  else()
-    execute_process(COMMAND pkg-config --variable=pkgdatadir wayland-protocols
-      OUTPUT_VARIABLE PROTOCOLS)
-    # strip trailing newline
-    string (REPLACE "\n" "" PROTOCOLS ${PROTOCOLS})
-  endif (NOT (CMAKE_VERSION VERSION_LESS 3.4))
+  pkg_get_variable(PROTOCOLS wayland-protocols pkgdatadir)
   # replace "//" with "/"
   string (REPLACE "//" "/" PROTOCOLS ${PROTOCOLS})
   if (NOT(EXISTS ${PROTOCOLS}/stable/xdg-shell/xdg-shell.xml))
@@ -737,7 +730,7 @@ FL_ADD_LIBRARY (fltk STATIC "${STATIC_FILES}")
 target_link_libraries (fltk ${OPTIONAL_LIBS})
 
 if (FLTK_HAVE_CAIRO)
-  fl_target_link_directories (fltk PUBLIC "${PKG_CAIRO_LIBRARY_DIRS}")
+  target_link_directories (fltk PUBLIC ${PKG_CAIRO_LIBRARY_DIRS})
 endif()
 
 #######################################################################
@@ -785,7 +778,7 @@ if (OPTION_BUILD_SHARED_LIBS AND NOT MSVC)
 
   FL_ADD_LIBRARY (fltk SHARED "${SHARED_FILES}")
   target_link_libraries (fltk_SHARED ${OPTIONAL_LIBS} ${PKG_CAIRO_LIBRARIES})
-  fl_target_link_directories (fltk_SHARED PUBLIC "${PKG_CAIRO_LIBRARY_DIRS}")
+  target_link_directories (fltk_SHARED PUBLIC ${PKG_CAIRO_LIBRARY_DIRS})
 
   ###################################################################