build: Tie interface age to the development cycle

We don't want to increase the interface age manually, because we're
going to end up forgetting about it.

Instead, we should tie it to the rest of the version:

 - in stable (even minor) cycles, we don't add new API; the interface
   age is the same as the micro version
 - in unstable (odd minor) cycles, every new release might have new API,
   or updates to newly added API; keep the interface age to 0

This removes one more manual thing to change during release, and keeps
us honest with our promise not to add symbols during stable cycles.

diff --git a/meson.build b/meson.build
index 35a3b4ebd060334d33c68d2b3957c5998d946ada..26f9b8e780de28a3734c49d9809781835145062e 100644 (file)
--- a/meson.build
+++ b/meson.build
@@ -30,15 +30,26 @@ add_project_arguments('-DG_LOG_USE_STRUCTURED=1', language: 'c')
 add_project_arguments('-DGLIB_DISABLE_DEPRECATION_WARNINGS', language: 'c')
 
 # Making releases:
-#  1. gtk_micro_version += 1;
-#  2. gtk_interface_age += 1;
-#  3. if any functions have been added, set gtk_interface_age to 0.
-#  4. if backwards compatibility has been broken, we're in trouble
+#  1. new development cycle:
+#    a. gtk_minor_version += 1
+#    b. gtk_micro_version = 0
+#  2. new stable cycle:
+#    a. gtk_minor_version += 1
+#    b. gtk_micro_version = 0
+#  3. every new release:
+#    a. gtk_micro_version += 1
 gtk_version       = meson.project_version()
 gtk_major_version = gtk_version.split('.')[0].to_int()
 gtk_minor_version = gtk_version.split('.')[1].to_int()
 gtk_micro_version = gtk_version.split('.')[2].to_int()
-gtk_interface_age = 0
+
+# Interface age gets reset during development cycles, when
+# we add new API; new micro versions of the same minor
+# stable cycle will have the same interface age
+#
+# If new API is added during a stable cycle, reset to 0
+gtk_interface_age = gtk_minor_version.is_odd() ? 0 : gtk_micro_version
+
 add_project_arguments('-DGTK_VERSION="@0@"'.format(meson.project_version()), language: 'c')
 
 add_project_arguments('-D_GNU_SOURCE', language: 'c')