Initial pass on API stability guarantees

This introduces -DWLR_USE_UNSTABLE and adds information regarding the
stability status to all headers. I started with a conservative set of
headers to mark as stable:

- types/wlr_matrix.h
- util/edges.h
- util/log.h
- util/region.h
- xcursor.h

6 files changed, 48 insertions, 0 deletions

diff --git a/include/wlr/backend/drm.h b/include/wlr/backend/drm.h
index 7f41ca15..a8a5525e 100644
--- a/include/wlr/backend/drm.h
+++ b/include/wlr/backend/drm.h
@@ -1,3 +1,11 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
 #ifndef WLR_BACKEND_DRM_H
 #define WLR_BACKEND_DRM_H
 
diff --git a/include/wlr/backend/headless.h b/include/wlr/backend/headless.h
index 02c7cd11..eab102e2 100644
--- a/include/wlr/backend/headless.h
+++ b/include/wlr/backend/headless.h
@@ -1,3 +1,11 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
 #ifndef WLR_BACKEND_HEADLESS_H
 #define WLR_BACKEND_HEADLESS_H
 
diff --git a/include/wlr/backend/interface.h b/include/wlr/backend/interface.h
index 42b39a16..f3dee69b 100644
--- a/include/wlr/backend/interface.h
+++ b/include/wlr/backend/interface.h
@@ -1,3 +1,11 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
 #ifndef WLR_BACKEND_INTERFACE_H
 #define WLR_BACKEND_INTERFACE_H
 
diff --git a/include/wlr/backend/libinput.h b/include/wlr/backend/libinput.h
index 92d31415..1a2ab294 100644
--- a/include/wlr/backend/libinput.h
+++ b/include/wlr/backend/libinput.h
@@ -1,3 +1,11 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
 #ifndef WLR_BACKEND_LIBINPUT_H
 #define WLR_BACKEND_LIBINPUT_H
 
diff --git a/include/wlr/backend/multi.h b/include/wlr/backend/multi.h
index 1e04dba4..7137b075 100644
--- a/include/wlr/backend/multi.h
+++ b/include/wlr/backend/multi.h
@@ -1,3 +1,11 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
 #ifndef WLR_BACKEND_MULTI_H
 #define WLR_BACKEND_MULTI_H
 
diff --git a/include/wlr/backend/session/interface.h b/include/wlr/backend/session/interface.h
index b35ed71d..5ccf9c8a 100644
--- a/include/wlr/backend/session/interface.h
+++ b/include/wlr/backend/session/interface.h
@@ -1,3 +1,11 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
 #ifndef WLR_BACKEND_SESSION_INTERFACE_H
 #define WLR_BACKEND_SESSION_INTERFACE_H