commit 5417ea5f1f33f62e2511bda74477da05dce900a3
Author:     Jordan Williams <jordan@jwillikers.com>
AuthorDate: Sun Apr 14 12:07:15 2024 -0500
Commit:     GitHub <noreply@github.com>
CommitDate: Sun Apr 14 19:07:15 2024 +0200

    CMake: Use imported targets for PkgConfig packages (#954)
    
    This carries include directories and the required link flags.
    Several libraries brought in through pkg_check_modules aren't linked correctly using the _LDFLAGS variables.
    Instead, they link the libraries directly with `-l`.
    This is problematic because it doesn't properly pull in the actual directory of the library being linked when it is not in a system library directory.
    Likewise, the necessary include directories for several of these targets aren't properly set either.
    Linking against the imported targets automatically pulls in the necessary include directories.

 CMake/options.cmake   | 37 +++++++++++++++++++------------------
 CMake/variables.cmake |  4 ++--
 src/CMakeLists.txt    | 18 +++++++++---------
 3 files changed, 30 insertions(+), 29 deletions(-)

diff --git CMake/options.cmake CMake/options.cmake
index fb7ce56..45ece76 100644
--- CMake/options.cmake
+++ CMake/options.cmake
@@ -273,10 +273,10 @@ if(UNIX)
     option(FLTK_BACKEND_WAYLAND "support the Wayland backend" ON)
   endif(NOT APPLE)
   if(FLTK_BACKEND_WAYLAND)
-    pkg_check_modules(WLDCLIENT wayland-client>=1.18)
-    pkg_check_modules(WLDCURSOR wayland-cursor)
-    pkg_check_modules(WLDPROTO wayland-protocols>=1.15)
-    pkg_check_modules(XKBCOMMON xkbcommon)
+    pkg_check_modules(WLDCLIENT IMPORTED_TARGET wayland-client>=1.18)
+    pkg_check_modules(WLDCURSOR IMPORTED_TARGET wayland-cursor)
+    pkg_check_modules(WLDPROTO IMPORTED_TARGET wayland-protocols>=1.15)
+    pkg_check_modules(XKBCOMMON IMPORTED_TARGET xkbcommon)
     if(NOT(WLDCLIENT_FOUND AND WLDCURSOR_FOUND AND WLDPROTO_FOUND AND XKBCOMMON_FOUND))
       message(STATUS "Not all software modules 'wayland-client>=1.18 wayland-cursor wayland-protocols>=1.15 xkbcommon' are present")
       message(STATUS "Consequently, FLTK_BACKEND_WAYLAND is turned off.")
@@ -333,7 +333,7 @@ if(UNIX)
     unset(FLTK_USE_PANGO CACHE)
     set(FLTK_USE_PANGO TRUE CACHE BOOL "use lib Pango")
     if(FLTK_USE_SYSTEM_LIBDECOR)
-      pkg_check_modules(SYSTEM_LIBDECOR libdecor-0>0.2.2 QUIET)
+      pkg_check_modules(SYSTEM_LIBDECOR IMPORTED_TARGET libdecor-0>0.2.2 QUIET)
       if(NOT SYSTEM_LIBDECOR_FOUND)
         message(STATUS "Warning: system libdecor doesn't satisfy version > 0.2.2,")
         message(STATUS "         using bundled libdecor library instead.")
@@ -601,13 +601,14 @@ endif()
 
 if(FLTK_BUILD_GL)
   if(FLTK_BACKEND_WAYLAND)
-    pkg_check_modules(WLD_EGL wayland-egl)
-    pkg_check_modules(PKG_EGL egl)
-    pkg_check_modules(PKG_GL gl)
-    if(NOT (WLD_EGL_FOUND AND PKG_EGL_FOUND AND PKG_GL_FOUND))
-      message(STATUS "Modules 'wayland-egl, egl, and gl' are required to build for the Wayland backend.")
+    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_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))
+    endif(NOT (WLD_EGL_FOUND AND PKG_EGL_FOUND AND PKG_GL_FOUND AND PKG_GLU_FOUND))
   endif(FLTK_BACKEND_WAYLAND)
   if(FLTK_BACKEND_X11)
     set(OPENGL_FOUND TRUE)
@@ -655,7 +656,7 @@ if(OPENGL_FOUND)
   elseif(APPLE AND NOT FLTK_BACKEND_X11)
     set(GLLIBS "-framework OpenGL")
   elseif(FLTK_BACKEND_WAYLAND)
-    set(GLLIBS "-lwayland-egl -lEGL -lGLU -lGL")
+    set(GLLIBS PkgConfig::WLD_EGL PkgConfig::PKG_EGL PkgConfig::PKG_GLU PkgConfig::PKG_GL)
   else()
     set(GLLIBS "-lGLU -lGL")
   endif(WIN32)
@@ -825,11 +826,11 @@ endif(USE_PANGOXFT)
 
 #######################################################################
 if((X11_Xft_FOUND OR NOT USE_PANGOXFT) AND FLTK_USE_PANGO)
-  pkg_check_modules(CAIRO cairo)
+  pkg_check_modules(CAIRO IMPORTED_TARGET cairo)
   if(USE_PANGOXFT)
-    pkg_check_modules(PANGOXFT pangoxft)
+    pkg_check_modules(PANGOXFT IMPORTED_TARGET pangoxft)
   endif(USE_PANGOXFT)
-  pkg_check_modules(PANGOCAIRO pangocairo)
+  pkg_check_modules(PANGOCAIRO IMPORTED_TARGET pangocairo)
 
   if((PANGOXFT_FOUND OR NOT USE_PANGOXFT) AND PANGOCAIRO_FOUND AND CAIRO_FOUND)
     if(USE_PANGOXFT)
@@ -860,9 +861,9 @@ 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 ${PANGOXFT_LDFLAGS})
+      list(APPEND FLTK_LDLIBS PkgConfig::PANGOXFT)
     endif(USE_PANGOXFT)
-    list(APPEND FLTK_LDLIBS ${PANGOCAIRO_LDFLAGS})
+    list(APPEND FLTK_LDLIBS PkgConfig::PANGOCAIRO)
     list(REMOVE_DUPLICATES FLTK_LDLIBS)
 
     # *FIXME* Libraries should not be added explicitly if possible
@@ -936,7 +937,7 @@ if(FLTK_BACKEND_WAYLAND)
 
   # Note: Disable FLTK_USE_LIBDECOR_GTK to get cairo titlebars rather than GTK
   if(FLTK_USE_LIBDECOR_GTK)
-    pkg_check_modules(GTK gtk+-3.0)
+    pkg_check_modules(GTK IMPORTED_TARGET gtk+-3.0)
     if(GTK_FOUND)
       list(APPEND FLTK_BUILD_INCLUDE_DIRECTORIES ${GTK_INCLUDE_DIRS})
     else()
diff --git CMake/variables.cmake CMake/variables.cmake
index cbf6ffd..20a36ed 100644
--- CMake/variables.cmake
+++ CMake/variables.cmake
@@ -45,9 +45,9 @@ if(WIN32)
 elseif(APPLE AND NOT FLTK_BACKEND_X11)
   list(APPEND FLTK_LDLIBS ${FLTK_COCOA_FRAMEWORKS})
 elseif(FLTK_BACKEND_WAYLAND)
-  list(APPEND FLTK_LDLIBS "-lwayland-cursor -lwayland-client -lxkbcommon -ldbus-1")
+  list(APPEND FLTK_LDLIBS PkgConfig::WLDCURSOR PkgConfig::WLDCLIENT PkgConfig::XKBCOMMON PkgConfig::DBUS)
   if(USE_SYSTEM_LIBDECOR)
-    list(APPEND FLTK_LDLIBS "-ldecor-0")
+    list(APPEND FLTK_LDLIBS PkgConfig::SYSTEM_LIBDECOR)
   endif(USE_SYSTEM_LIBDECOR)
 else()
   list(APPEND FLTK_LDLIBS -lm)
diff --git src/CMakeLists.txt src/CMakeLists.txt
index b12880c..326fb5d 100644
--- src/CMakeLists.txt
+++ src/CMakeLists.txt
@@ -535,7 +535,7 @@ if(FLTK_USE_X11)
 endif(FLTK_USE_X11)
 
 if(FLTK_BACKEND_WAYLAND)
-  pkg_check_modules(DBUS dbus-1)
+  pkg_check_modules(DBUS IMPORTED_TARGET dbus-1)
   set(IDIRS "${CMAKE_CURRENT_BINARY_DIR}")
   set(CDEFS "_GNU_SOURCE;HAVE_MEMFD_CREATE;HAVE_MKOSTEMP;HAVE_POSIX_FALLOCATE")
   set(COPTS "-fPIC")
@@ -676,10 +676,10 @@ endif(HAVE_XRENDER)
 
 if(USE_PANGO)
   ### FIXME ###  This needs to use the PKG_* variables directly
-  list(APPEND OPTIONAL_LIBS ${HAVE_LIB_PANGO} ${HAVE_LIB_PANGOCAIRO})
-  list(APPEND OPTIONAL_LIBS ${HAVE_LIB_CAIRO} ${HAVE_LIB_GOBJECT})
+  list(APPEND OPTIONAL_LIBS ${HAVE_LIB_PANGO} PkgConfig::PANGOCAIRO)
+  list(APPEND OPTIONAL_LIBS PkgConfig::CAIRO ${HAVE_LIB_GOBJECT})
   if(USE_PANGOXFT)
-    list(APPEND OPTIONAL_LIBS ${HAVE_LIB_PANGOXFT})
+    list(APPEND OPTIONAL_LIBS PkgConfig::PANGOXFT)
   endif(USE_PANGOXFT)
 endif(USE_PANGO)
 
@@ -754,16 +754,16 @@ if(UNIX AND FLTK_BACKEND_WAYLAND)
   endif()
 
   if(FLTK_USE_GL)
-    list(APPEND OPTIONAL_LIBS "-lwayland-egl -lEGL")
+    list(APPEND OPTIONAL_LIBS PkgConfig::WLD_EGL PkgConfig::PKG_EGL)
   endif(FLTK_USE_GL)
   if(USE_SYSTEM_LIBDECOR)
-    list(APPEND OPTIONAL_LIBS "-ldecor-0")
+    list(APPEND OPTIONAL_LIBS PkgConfig::SYSTEM_LIBDECOR)
   elseif(GTK_FOUND AND FLTK_USE_LIBDECOR_GTK)
-      list(APPEND OPTIONAL_LIBS ${GTK_LDFLAGS} )
+      list(APPEND OPTIONAL_LIBS PkgConfig::GTK)
   endif(USE_SYSTEM_LIBDECOR)
-  list(APPEND OPTIONAL_LIBS "-lwayland-cursor -lwayland-client -lxkbcommon -ldl")
+  list(APPEND OPTIONAL_LIBS PkgConfig::WLDCURSOR PkgConfig::WLDCLIENT PkgConfig::XKBCOMMON -ldl)
   if(DBUS_FOUND)
-    list(APPEND OPTIONAL_LIBS "${DBUS_LDFLAGS}")
+    list(APPEND OPTIONAL_LIBS PkgConfig::DBUS)
   endif(DBUS_FOUND)
 endif(UNIX AND FLTK_BACKEND_WAYLAND)