Fix and improve generation of fltk-config (#954 and more)

Parts of this commit fix the usage of CMake targets in the generation
process of fltk-config modified by PR #954.

The rest improves handling of variables used to generate fltk-config,
removes obsolete comments, documents variables like GLLIBS etc. which
had to be done anyway.

3 files changed, 44 insertions, 37 deletions

diff --git a/CMake/options.cmake b/CMake/options.cmake
index 45ece7632..b242c5f40 100644
--- a/CMake/options.cmake
+++ b/CMake/options.cmake
@@ -603,13 +603,16 @@ if(FLTK_BUILD_GL)
   if(FLTK_BACKEND_WAYLAND)
     pkg_check_modules(WLD_EGL IMPORTED_TARGET wayland-egl)
     pkg_check_modules(PKG_EGL IMPORTED_TARGET egl)
-    pkg_check_modules(PKG_GL IMPORTED_TARGET gl)
+    pkg_check_modules(PKG_GL  IMPORTED_TARGET gl)
     pkg_check_modules(PKG_GLU IMPORTED_TARGET glu)
+
     if(NOT (WLD_EGL_FOUND AND PKG_EGL_FOUND AND PKG_GL_FOUND AND PKG_GLU_FOUND))
       message(STATUS "Modules 'wayland-egl, egl, gl, and glu' are required to build for the Wayland backend.")
       message(FATAL_ERROR "*** Aborting ***")
-    endif(NOT (WLD_EGL_FOUND AND PKG_EGL_FOUND AND PKG_GL_FOUND AND PKG_GLU_FOUND))
+    endif()
+
   endif(FLTK_BACKEND_WAYLAND)
+
   if(FLTK_BACKEND_X11)
     set(OPENGL_FOUND TRUE)
     find_library(OPENGL_LIB GL)
@@ -628,7 +631,7 @@ if(FLTK_BUILD_GL)
       set(HAVE_GL_GLU_H ${HAVE_OPENGL_GLU_H})
     endif(APPLE)
   endif(FLTK_BACKEND_X11)
-else()
+else(FLTK_BUILD_GL)
   set(OPENGL_FOUND FALSE)
   set(HAVE_GL FALSE)
   set(HAVE_GL_GLU_H FALSE)
@@ -641,24 +644,32 @@ mark_as_advanced(OPENGL_LIB) # internal cache variable, not relevant for users
 # from the cache above. It has been marked "advanced" before in resources.cmake.
 mark_as_advanced(HAVE_GL_GLU_H)
 
+# Note: GLLIBS is a CMake 'list' and is used exclusively to generate fltk-config !
+
+# FIXME, this should be improved!
+# We should probably deduct this from OPENGL_LIBRARIES but it turned
+# out to be difficult since FindOpenGL seems to return different
+# syntax depending on the platform (and maybe also CMake version).
+# Hence we use the following code...
+
+set(GLLIBS)
+set(FLTK_GL_FOUND FALSE)
+
 if(OPENGL_FOUND)
+  set(FLTK_GL_FOUND TRUE)
   find_path(OPENGL_GLU_INCLUDE_DIR NAMES GL/glu.h OpenGL/glu.h HINTS ${OPENGL_INCLUDE_DIR} ${X11_INCLUDE_DIR})
   set(CMAKE_REQUIRED_INCLUDES ${OPENGL_INCLUDE_DIR}/GL ${OPENGL_GLU_INCLUDE_DIR})
 
-  # Set GLLIBS (used in fltk-config).
-  # We should probably deduct this from OPENGL_LIBRARIES but it turned
-  # out to be difficult since FindOpenGL seems to return different
-  # syntax depending on the platform (and maybe also CMake version).
-  # Hence we use the following code...
-
   if(WIN32)
-    set(GLLIBS "-lglu32 -lopengl32")
+    list(APPEND GLLIBS -lglu32 -lopengl32)
   elseif(APPLE AND NOT FLTK_BACKEND_X11)
-    set(GLLIBS "-framework OpenGL")
+    list(APPEND GLLIBS "-framework OpenGL")
   elseif(FLTK_BACKEND_WAYLAND)
-    set(GLLIBS PkgConfig::WLD_EGL PkgConfig::PKG_EGL PkgConfig::PKG_GLU PkgConfig::PKG_GL)
+    foreach(_lib WLD_EGL PKG_EGL PKG_GLU PKG_GL)
+      list(APPEND GLLIBS ${${_lib}_LDFLAGS})
+    endforeach(_lib )
   else()
-    set(GLLIBS "-lGLU -lGL")
+    list(APPEND GLLIBS -lGLU -lGL)
   endif(WIN32)
 
   # check if function glXGetProcAddressARB exists
@@ -667,11 +678,6 @@ if(OPENGL_FOUND)
   check_function_exists(glXGetProcAddressARB HAVE_GLXGETPROCADDRESSARB)
   set(CMAKE_REQUIRED_LIBRARIES ${TEMP_REQUIRED_LIBRARIES})
   unset(TEMP_REQUIRED_LIBRARIES)
-
-  set(FLTK_GL_FOUND TRUE)
-else()
-  set(FLTK_GL_FOUND FALSE)
-  set(GLLIBS)
 endif(OPENGL_FOUND)
 
 #######################################################################
@@ -861,10 +867,9 @@ if((X11_Xft_FOUND OR NOT USE_PANGOXFT) AND FLTK_USE_PANGO)
 
     # add required libraries to fltk-config ...
     if(USE_PANGOXFT)
-      list(APPEND FLTK_LDLIBS PkgConfig::PANGOXFT)
+      list(APPEND FLTK_LDLIBS ${PANGOXFT_LDFLAGS})
     endif(USE_PANGOXFT)
-    list(APPEND FLTK_LDLIBS PkgConfig::PANGOCAIRO)
-    list(REMOVE_DUPLICATES FLTK_LDLIBS)
+    list(APPEND FLTK_LDLIBS ${PANGOCAIRO_LDFLAGS})
 
     # *FIXME* Libraries should not be added explicitly if possible
     if(FLTK_BACKEND_WAYLAND AND FLTK_USE_LIBDECOR_GTK AND NOT USE_SYSTEM_LIBDECOR)
@@ -874,8 +879,6 @@ if((X11_Xft_FOUND OR NOT USE_PANGOXFT) AND FLTK_USE_PANGO)
       list(APPEND FLTK_LDLIBS -lX11)
     endif()
 
-    list(REMOVE_DUPLICATES FLTK_LDLIBS)
-
     if(APPLE)
       get_filename_component(PANGO_L_PATH ${HAVE_LIB_PANGO} PATH)
       set(LDFLAGS "${LDFLAGS} -L${PANGO_L_PATH}")
diff --git a/CMake/setup.cmake b/CMake/setup.cmake
index ed00be391..3b6708416 100644
--- a/CMake/setup.cmake
+++ b/CMake/setup.cmake
@@ -83,10 +83,8 @@ set(FLTK_BUILD_INCLUDE_DIRECTORIES)
 
 set(FLTK_LDLIBS "")
 set(FLTK_LIBRARIES "")
-set(GLLIBS "")
 set(IMAGELIBS "")
 set(LDFLAGS "")
-set(LIBS "")
 set(LINK_LIBS "")
 set(STATICIMAGELIBS "")
 
diff --git a/CMake/variables.cmake b/CMake/variables.cmake
index 20a36eda8..cb5d62481 100644
--- a/CMake/variables.cmake
+++ b/CMake/variables.cmake
@@ -24,7 +24,6 @@ if(DEBUG_VARIABLES_CMAKE)
   fl_debug_var(CMAKE_DL_LIBS)
   fl_debug_var(CMAKE_EXE_LINKER_FLAGS)
   fl_debug_var(LDFLAGS)
-  fl_debug_var(LIBS)
   fl_debug_var(GLLIBS)
   fl_debug_var(IMAGELIBS)
   fl_debug_var(STATICIMAGELIBS)
@@ -45,9 +44,11 @@ if(WIN32)
 elseif(APPLE AND NOT FLTK_BACKEND_X11)
   list(APPEND FLTK_LDLIBS ${FLTK_COCOA_FRAMEWORKS})
 elseif(FLTK_BACKEND_WAYLAND)
-  list(APPEND FLTK_LDLIBS PkgConfig::WLDCURSOR PkgConfig::WLDCLIENT PkgConfig::XKBCOMMON PkgConfig::DBUS)
+  foreach(_lib WLDCURSOR WLDCLIENT XKBCOMMON DBUS)
+    list(APPEND FLTK_LDLIBS "${${_lib}_LDFLAGS}")
+  endforeach()
   if(USE_SYSTEM_LIBDECOR)
-    list(APPEND FLTK_LDLIBS PkgConfig::SYSTEM_LIBDECOR)
+    list(APPEND FLTK_LDLIBS ${SYSTEM_LIBDECOR_LDFLAGS})
   endif(USE_SYSTEM_LIBDECOR)
 else()
   list(APPEND FLTK_LDLIBS -lm)
@@ -115,8 +116,19 @@ else()
   endif(LIB_zlib)
 endif(FLTK_USE_BUNDLED_ZLIB)
 
-string(REPLACE ";" " " IMAGELIBS "${IMAGELIBS}")
-string(REPLACE ";" " " STATICIMAGELIBS "${STATICIMAGELIBS}")
+# remove duplicates from CMake "list" variables for fltk-config
+
+list(REMOVE_DUPLICATES GLLIBS)
+list(REMOVE_DUPLICATES FLTK_LDLIBS)
+list(REMOVE_DUPLICATES IMAGELIBS)
+list(REMOVE_DUPLICATES STATICIMAGELIBS)
+
+# convert CMake lists to strings with spaces for fltk-config
+
+string(REPLACE ";" " " GLLIBS           "${GLLIBS}")
+string(REPLACE ";" " " LIBS             "${FLTK_LDLIBS}")
+string(REPLACE ";" " " IMAGELIBS        "${IMAGELIBS}")
+string(REPLACE ";" " " STATICIMAGELIBS  "${STATICIMAGELIBS}")
 
 #######################################################################
 set(CC ${CMAKE_C_COMPILER})
@@ -136,12 +148,6 @@ endforeach(arg ${FLTK_CFLAGS})
 
 set(CXXFLAGS "${CFLAGS}")
 
-foreach(arg ${FLTK_LDLIBS})
-  set(LINK_LIBS "${LINK_LIBS} ${arg}")
-endforeach(arg ${FLTK_LDLIBS})
-
-set(LIBS "${LINK_LIBS}")
-
 if(${CMAKE_SYSTEM_NAME} STREQUAL "AIX")
     set(SHAREDSUFFIX "_s")
 else()
@@ -154,11 +160,11 @@ if(DEBUG_VARIABLES_CMAKE)
   fl_debug_var(CMAKE_DL_LIBS)
   fl_debug_var(CMAKE_EXE_LINKER_FLAGS)
   fl_debug_var(LDFLAGS)
+  fl_debug_var(FLTK_LDLIBS)
   fl_debug_var(LIBS)
   fl_debug_var(GLLIBS)
   fl_debug_var(IMAGELIBS)
   fl_debug_var(STATICIMAGELIBS)
-  fl_debug_var(FLTK_LDLIBS)
   fl_debug_var(LIB_jpeg)
   fl_debug_var(LIB_png)
   fl_debug_var(LIB_zlib)