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

7 files changed, 56 insertions, 0 deletions

diff --git a/include/wlr/interfaces/wlr_input_device.h b/include/wlr/interfaces/wlr_input_device.h
index a5c513b7..05248bf6 100644
--- a/include/wlr/interfaces/wlr_input_device.h
+++ b/include/wlr/interfaces/wlr_input_device.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_INTERFACES_WLR_INPUT_DEVICE_H
 #define WLR_INTERFACES_WLR_INPUT_DEVICE_H
 
diff --git a/include/wlr/interfaces/wlr_keyboard.h b/include/wlr/interfaces/wlr_keyboard.h
index c9a13fd7..5d537827 100644
--- a/include/wlr/interfaces/wlr_keyboard.h
+++ b/include/wlr/interfaces/wlr_keyboard.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_INTERFACES_WLR_KEYBOARD_H
 #define WLR_INTERFACES_WLR_KEYBOARD_H
 
diff --git a/include/wlr/interfaces/wlr_output.h b/include/wlr/interfaces/wlr_output.h
index 8f87408a..2224932f 100644
--- a/include/wlr/interfaces/wlr_output.h
+++ b/include/wlr/interfaces/wlr_output.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_INTERFACES_WLR_OUTPUT_H
 #define WLR_INTERFACES_WLR_OUTPUT_H
 
diff --git a/include/wlr/interfaces/wlr_pointer.h b/include/wlr/interfaces/wlr_pointer.h
index f0cf9081..fd3ab102 100644
--- a/include/wlr/interfaces/wlr_pointer.h
+++ b/include/wlr/interfaces/wlr_pointer.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_INTERFACES_WLR_POINTER_H
 #define WLR_INTERFACES_WLR_POINTER_H
 
diff --git a/include/wlr/interfaces/wlr_tablet_pad.h b/include/wlr/interfaces/wlr_tablet_pad.h
index 5ec1e3eb..86bbe9c3 100644
--- a/include/wlr/interfaces/wlr_tablet_pad.h
+++ b/include/wlr/interfaces/wlr_tablet_pad.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_INTERFACES_WLR_TABLET_PAD_H
 #define WLR_INTERFACES_WLR_TABLET_PAD_H
 
diff --git a/include/wlr/interfaces/wlr_tablet_tool.h b/include/wlr/interfaces/wlr_tablet_tool.h
index 12b2e32e..9cfc3ca0 100644
--- a/include/wlr/interfaces/wlr_tablet_tool.h
+++ b/include/wlr/interfaces/wlr_tablet_tool.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_INTERFACES_WLR_TABLET_TOOL_H
 #define WLR_INTERFACES_WLR_TABLET_TOOL_H
 
diff --git a/include/wlr/interfaces/wlr_touch.h b/include/wlr/interfaces/wlr_touch.h
index 63bac6b8..cc426332 100644
--- a/include/wlr/interfaces/wlr_touch.h
+++ b/include/wlr/interfaces/wlr_touch.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_INTERFACES_WLR_TOUCH_H
 #define WLR_INTERFACES_WLR_TOUCH_H