Remove hardcoded version numbers: part 1

The goal is to change the version number for a new release only in
CMakeLists.txt. This is the first step.

Details:

- CMake/gen_config.cmake: this new file is included to generate the
  header files config.h (private, root directory), and FL/fl_config.h
  (public, can be installed). This file implements also ABI version
  checks (removed from FL/Enumerations.H and with more checks).
  Warnings are issued if the chosen ABI version is invalid.
- CMake/export.cmake: code to generate 'config.h' was moved to
  CMake/gen_config.cmake.
- CMake/options.cmake: set default of FLTK_BUILD_FORMS=OFF + comments
- CMakeLists.txt: move generation of FL/fl_config.h to gen_config.cmake,
  add API and ABI versions to CMake summary,
- FL/Enumerations.H: remove most of the version number details which
  are now included in FL/fl_config.h. This needed also some doxygen
  related changes.
- README.CMake.txt: improve docs of FL_ABI_VERSION and some more.
  Reflect the new default of CMake option FLTK_BUILD_FORMS (OFF).
- documentation/Doxyfile.in: add FL/fl_config.h to file list. This
  file is created in the build tree (and may be "installed").
- fl_config.h.in: add version number details that have been moved here
  from Enumerations.H (used to generate FL/fl_config.h).

1 files changed, 12 insertions, 100 deletions

diff --git a/FL/Enumerations.H b/FL/Enumerations.H
index 5bc2951aa..6674e7463 100644
--- a/FL/Enumerations.H
+++ b/FL/Enumerations.H
@@ -23,8 +23,10 @@
 
 /*
  ******************************************************************************
- * FL_ABI_VERSION is defined by configure or CMake since FLTK 1.3.4.
+ * FL_ABI_VERSION is defined by CMake since FLTK 1.3.4.
  * It is written to FL/fl_config.h and #included here.
+ * Since FLTK 1.5.0 all version checks of FL_ABI_VERSION are done by CMake
+ * in CMake/gen_config.cmake.
  ******************************************************************************
  * For more informations on FL_ABI_VERSION see README.abi-version.txt.
  ******************************************************************************
@@ -32,41 +34,16 @@
 
 #include <FL/fl_config.h>
 
-#  include "Fl_Export.H"
-#  include "fl_types.h"
-#  include <FL/platform_types.h> // for FL_COMMAND and FL_CONTROL
+#include "Fl_Export.H"
+#include "fl_types.h"
+#include <FL/platform_types.h> // for FL_COMMAND and FL_CONTROL
 
-// Keep the following comment in sync with the values below for searching
-// Current FLTK version: 1.5.0
+// Doxygen group 'version_numbers' is defined in file FL/fl_config.h
+// which is generated by CMake from fl_config.h.in and included above.
 
-/** \name Version Numbers
-
-    FLTK defines some constants to help the programmer to
-    find out, for which FLTK version a program is compiled.
-
-    The following constants are defined:
- */
-/**@{*/
-
-/**
-   The major release version of this FLTK library.
-   \see FL_VERSION
- */
-#define FL_MAJOR_VERSION        1
-
-/**
-   The minor release version for this library.
-
-   FLTK remains mostly source-code compatible between minor version changes.
- */
-#define FL_MINOR_VERSION        5
-
-/**
-   The patch version for this library.
-
-   FLTK remains binary compatible between patches.
- */
-#define FL_PATCH_VERSION        0
+/** \addtogroup version_numbers
+  @{
+*/
 
 /**
     The FLTK version number as a \em double.
@@ -113,73 +90,8 @@
  */
 #define FL_API_VERSION (FL_MAJOR_VERSION*10000 + FL_MINOR_VERSION*100 + FL_PATCH_VERSION)
 
-/**
-    The FLTK ABI (Application Binary Interface) version number as an \em int.
-
-    FL_ABI_VERSION is an \em int that describes the major, minor, and patch
-    ABI version numbers in the same format as FL_API_VERSION.
-
-    The ABI version number \p FL_ABI_VERSION is usually the same as the
-    API version \p FL_API_VERSION with the last two digits set to '00'.
-
-    FLTK retains the ABI (Application Binary Interface) during patch
-    releases of the same major and minor versions. Examples:
-
-    \verbatim
-      FLTK Version  FL_API_VERSION  FL_ABI_VERSION  FL_VERSION (deprecated)
-        1.3.0          10300           10300           1.0300
-        1.3.4          10304           10300           1.0304
-    \endverbatim
-
-    Version 1.2.3 is actually stored as 10203 to allow for more than 9
-    minor and patch releases.
-
-    The FL_MAJOR_VERSION, FL_MINOR_VERSION, and FL_PATCH_VERSION constants
-    give the integral values for the major, minor, and patch releases
-    respectively.
-
-    To enable new ABI-breaking features in patch releases you can configure
-    FLTK to use a higher FL_ABI_VERSION.
-
-    \see README.abi-version.txt
- */
-#ifndef FL_ABI_VERSION
-#define FL_ABI_VERSION (FL_MAJOR_VERSION*10000 + FL_MINOR_VERSION*100)
-#endif
-
-/*
-  Check if FL_ABI_VERSION is out of allowed range; redefine if necessary.
-
-  This is done to prevent users from defining an illegal ABI version.
-
-  Rule: FL_MAJOR_VERSION * 10000 + FL_MINOR_VERSION * 100
-          <= FL_ABI_VERSION <= FL_API_VERSION + 1.
-
-  Since FLTK 1.4.2+ (Git commits after release 1.4.2) FL_ABI_VERSION is
-  allowed to be one higher than FL_API_VERSION so ABI changes in Git
-  targeted at the *next* release (e.g. 1.4.3) can be used.
-
-  Example: Commits after release FLTK 1.4.2 (before release 1.4.3):
-
-    10400 <= FL_ABI_VERSION <= 10403
-
-  Note: configure + CMake can be used to define FL_ABI_VERSION, but they
-  do not check validity. This is done here.
-*/
-
-#if FL_ABI_VERSION < FL_MAJOR_VERSION*10000 + FL_MINOR_VERSION*100
-
-# undef FL_ABI_VERSION
-# define FL_ABI_VERSION (FL_MAJOR_VERSION*10000 + FL_MINOR_VERSION*100)
-
-#elif FL_ABI_VERSION > FL_API_VERSION + 1
-
-# undef FL_ABI_VERSION
-# define FL_ABI_VERSION FL_API_VERSION + 1
-
-#endif
 
-/**@}*/  // group: Version Numbers
+/** @} */  // end of group 'version_numbers'
 
 /**
     Every time a user moves the mouse pointer, clicks a button,