[build] use define WINPR_FALLTHROUGH

with c17 compatible compilers annotate with [[fallthrough]]

channels/urbdrc/client/libusb/libusb_udevice.c

@@ -288,7 +288,9 @@ static void LIBUSB_CALL func_iso_callback(struct libusb_transfer* transfer)
 			/* fallthrough */
 
 		case LIBUSB_TRANSFER_CANCELLED:
+			WINPR_FALLTHROUGH
 		case LIBUSB_TRANSFER_TIMED_OUT:
+			WINPR_FALLTHROUGH
 		case LIBUSB_TRANSFER_ERROR:
 		{
 			const UINT32 InterfaceId =

client/X11/xf_input.c

@@ -855,12 +855,16 @@ static int xf_input_handle_event_remote(xfContext* xfc, const XEvent* event)
 		{
 			case XI_TouchBegin:
 				xf_input_pens_unhover(xfc);
+				WINPR_FALLTHROUGH
 			case XI_TouchUpdate:
+				WINPR_FALLTHROUGH
 			case XI_TouchEnd:
 				xf_input_touch_remote(xfc, cookie.cc->data, cookie.cc->evtype);
 				break;
 			case XI_ButtonPress:
+				WINPR_FALLTHROUGH
 			case XI_Motion:
+				WINPR_FALLTHROUGH
 			case XI_ButtonRelease:
 			{
 				WLog_DBG(TAG, "checking for pen");
@@ -873,6 +877,7 @@ static int xf_input_handle_event_remote(xfContext* xfc, const XEvent* event)
 					break;
 				}
 			}
+				WINPR_FALLTHROUGH
 			default:
 				xf_input_pens_unhover(xfc);
 				xf_input_event(xfc, event, cookie.cc->data, cookie.cc->evtype);

libfreerdp/core/credssp_auth.c

@@ -707,6 +707,7 @@ void credssp_auth_free(rdpCredsspAuth* auth)
 				WINPR_ASSERT(auth->table->DeleteSecurityContext);
 				auth->table->DeleteSecurityContext(&auth->context);
 				/* FALLTHROUGH */
+				WINPR_FALLTHROUGH
 			case AUTH_STATE_CREDS:
 				WINPR_ASSERT(auth->table->FreeCredentialsHandle);
 				auth->table->FreeCredentialsHandle(&auth->credentials);

libfreerdp/core/gateway/rpc_client.c

@@ -287,6 +287,7 @@ static int rpc_client_recv_pdu(rdpRpc* rpc, RPC_PDU* pdu)
 						return -1;
 					}
 					/* FALLTHROUGH */
+					WINPR_FALLTHROUGH
 				case RPC_BIND_STATE_COMPLETE:
 					rpc_client_transition_to_state(rpc, RPC_CLIENT_STATE_CONTEXT_NEGOTIATED);
 

winpr/include/config/wtypes.h.in

@@ -20,6 +20,12 @@
 #ifndef WINPR_WTYPES_H
 #define WINPR_WTYPES_H
 
+#if defined(__STDC__) && defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201710L)
+#define WINPR_FALLTHROUGH [[fallthrough]]
+#else
+#define WINPR_FALLTHROUGH
+#endif
+
 /* Set by CMake during configuration */
 #cmakedefine WINPR_HAVE_STDINT_H
 #cmakedefine WINPR_HAVE_STDBOOL_H

winpr/libwinpr/ncrypt/ncrypt_pkcs11.c

@@ -207,6 +207,8 @@ static CK_RV object_load_attributes(NCryptP11ProviderHandle* provider, CK_SESSIO
 			if (!attributes_have_unallocated_buffers(attributes, count))
 				return rv;
 			/* fallthrough */
+			WINPR_FALLTHROUGH
+
 		case CKR_ATTRIBUTE_SENSITIVE:
 		case CKR_ATTRIBUTE_TYPE_INVALID:
 		case CKR_BUFFER_TOO_SMALL:

winpr/libwinpr/sspi/Kerberos/kerberos.c

@@ -818,6 +818,7 @@ static SECURITY_STATUS SEC_ENTRY kerberos_InitializeSecurityContextA(
 				goto bad_token;
 
 			/* Continue to AP-REQ */
+			WINPR_FALLTHROUGH
 
 		case KERBEROS_STATE_AP_REQ: