treewide: make type-check helpers take const pointers

backend/drm/backend.c

@@ -95,7 +95,7 @@ static const struct wlr_backend_impl backend_impl = {
 	.commit = backend_commit,
 };
 
-bool wlr_backend_is_drm(struct wlr_backend *b) {
+bool wlr_backend_is_drm(const struct wlr_backend *b) {
 	return b->impl == &backend_impl;
 }
 

backend/drm/drm.c

@@ -1299,7 +1299,7 @@ static const struct wlr_output_impl output_impl = {
 	.get_primary_formats = drm_connector_get_primary_formats,
 };
 
-bool wlr_output_is_drm(struct wlr_output *output) {
+bool wlr_output_is_drm(const struct wlr_output *output) {
 	return output->impl == &output_impl;
 }
 

backend/headless/backend.c

@@ -81,6 +81,6 @@ struct wlr_backend *wlr_headless_backend_create(struct wl_event_loop *loop) {
 	return &backend->backend;
 }
 
-bool wlr_backend_is_headless(struct wlr_backend *backend) {
+bool wlr_backend_is_headless(const struct wlr_backend *backend) {
 	return backend->impl == &backend_impl;
 }

backend/headless/output.c

@@ -106,7 +106,7 @@ static const struct wlr_output_impl output_impl = {
 	.move_cursor = output_move_cursor,
 };
 
-bool wlr_output_is_headless(struct wlr_output *wlr_output) {
+bool wlr_output_is_headless(const struct wlr_output *wlr_output) {
 	return wlr_output->impl == &output_impl;
 }
 

backend/libinput/backend.c

@@ -155,7 +155,7 @@ static const struct wlr_backend_impl backend_impl = {
 	.destroy = backend_destroy,
 };
 
-bool wlr_backend_is_libinput(struct wlr_backend *b) {
+bool wlr_backend_is_libinput(const struct wlr_backend *b) {
 	return b->impl == &backend_impl;
 }
 

backend/multi/backend.c

@@ -173,7 +173,7 @@ struct wlr_backend *wlr_multi_backend_create(struct wl_event_loop *loop) {
 	return &backend->backend;
 }
 
-bool wlr_backend_is_multi(struct wlr_backend *b) {
+bool wlr_backend_is_multi(const struct wlr_backend *b) {
 	return b->impl == &backend_impl;
 }
 

backend/wayland/backend.c

@@ -577,7 +577,7 @@ static const struct wlr_backend_impl backend_impl = {
 	.get_drm_fd = backend_get_drm_fd,
 };
 
-bool wlr_backend_is_wl(struct wlr_backend *b) {
+bool wlr_backend_is_wl(const struct wlr_backend *b) {
 	return b->impl == &backend_impl;
 }
 

backend/wayland/output.c

@@ -1027,7 +1027,7 @@ static const struct wlr_output_impl output_impl = {
 	.get_primary_formats = output_get_formats,
 };
 
-bool wlr_output_is_wl(struct wlr_output *wlr_output) {
+bool wlr_output_is_wl(const struct wlr_output *wlr_output) {
 	return wlr_output->impl == &output_impl;
 }
 

backend/x11/backend.c

@@ -218,7 +218,7 @@ static const struct wlr_backend_impl backend_impl = {
 	.get_drm_fd = backend_get_drm_fd,
 };
 
-bool wlr_backend_is_x11(struct wlr_backend *backend) {
+bool wlr_backend_is_x11(const struct wlr_backend *backend) {
 	return backend->impl == &backend_impl;
 }
 

backend/x11/output.c

@@ -711,7 +711,7 @@ void handle_x11_configure_notify(struct wlr_x11_output *output,
 	wlr_output_state_finish(&state);
 }
 
-bool wlr_output_is_x11(struct wlr_output *wlr_output) {
+bool wlr_output_is_x11(const struct wlr_output *wlr_output) {
 	return wlr_output->impl == &output_impl;
 }