[gnome-panel] build: update library version change process

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 9246e1cf2502568d8e9c20c2e34ebc349401027c
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Mon May 4 23:07:28 2020 +0300

    build: update library version change process

 configure.ac               | 33 +++++++++++++++++++++++----------
 libgnome-panel/Makefile.am |  2 +-
 2 files changed, 24 insertions(+), 11 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 5a1aa7640..28274f9fa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -92,16 +92,29 @@ dnl **************************************************************************
 
 GLIB_GSETTINGS
 
-# Before making a release, the LT_VERSION string should be modified.
-# The string is of the form C:R:A.
-# - If interfaces have been changed or added, but binary compatibility has
-#   been preserved, change to C+1:0:A+1
-# - If binary compatibility has been broken (eg removed or changed interfaces)
-#   change to C+1:0:0
-# - If the interface is the same as the previous version, change to C:R+1:A
-
-LIBGNOME_PANEL_LT_VERSION=1:0:1
-AC_SUBST([LIBGNOME_PANEL_LT_VERSION])
+dnl **************************************************************************
+dnl Library version information
+dnl **************************************************************************
+
+dnl Before making a release, the library version should be modified. Follow
+dnl these instructions sequentially:
+dnl 1. If the library source code has changed at all since the last update,
+dnl    then increment lt_revision.
+dnl 2. If any interfaces have been added, removed, or changed since the last
+dnl    update, increment lt_current, and set lt_revision to 0.
+dnl 3. If any interfaces have been added since the last public release, then
+dnl    increment lt_age.
+dnl 4. If any interfaces have been removed or changed since the last public
+dnl    release, then set lt_age to 0.
+
+m4_define([lt_current], [1])
+m4_define([lt_revision], [0])
+m4_define([lt_age], [1])
+m4_define([lt_version_info], [lt_current:lt_revision:lt_age])
+
+AC_SUBST([LT_VERSION_INFO], [lt_version_info])
+
+dnl **************************************************************************
 
 AC_ARG_ENABLE([documentation],
        AS_HELP_STRING([--enable-documentation], [enable man pages and HTML]),
diff --git a/libgnome-panel/Makefile.am b/libgnome-panel/Makefile.am
index 9626e9632..67e2b1872 100644
--- a/libgnome-panel/Makefile.am
+++ b/libgnome-panel/Makefile.am
@@ -41,7 +41,7 @@ libgnome_panel_la_CFLAGS = \
        $(NULL)
 
 libgnome_panel_la_LDFLAGS = \
-       -version-info $(LIBGNOME_PANEL_LT_VERSION) \
+       -version-info $(LT_VERSION_INFO) \
        $(WARN_LDFLAGS) \
        $(AM_LDFLAGS) \
        $(NULL)