Define SPA_FALLTHROUGH to make fall-through annotations work for all compilers

This is needed for example for Clang compiler which uses different
annotations than GCC. It will make WebRTC to happily use PipeWire
since the spa library is header-only and WebRTC defaults to use
Clang with -Wimplicit-fallthrough.

pipewire-alsa/alsa-plugins/pcm_pipewire.c

@@ -497,7 +497,7 @@ static int set_default_channels(struct spa_audio_info_raw *info)
 	case 7:
 		info->position[5] = SPA_AUDIO_CHANNEL_SL;
 		info->position[6] = SPA_AUDIO_CHANNEL_SR;
-		/* Fall through */
+		SPA_FALLTHROUGH
 	case 5:
 		info->position[3] = SPA_AUDIO_CHANNEL_RL;
 		info->position[4] = SPA_AUDIO_CHANNEL_RR;
@@ -508,17 +508,17 @@ static int set_default_channels(struct spa_audio_info_raw *info)
 	case 8:
 		info->position[6] = SPA_AUDIO_CHANNEL_SL;
 		info->position[7] = SPA_AUDIO_CHANNEL_SR;
-		/* Fall through */
+		SPA_FALLTHROUGH
 	case 6:
 		info->position[4] = SPA_AUDIO_CHANNEL_RL;
 		info->position[5] = SPA_AUDIO_CHANNEL_RR;
-		/* Fall through */
+		SPA_FALLTHROUGH
 	case 4:
 		info->position[3] = SPA_AUDIO_CHANNEL_LFE;
-		/* Fall through */
+		SPA_FALLTHROUGH
 	case 3:
 		info->position[2] = SPA_AUDIO_CHANNEL_FC;
-		/* Fall through */
+		SPA_FALLTHROUGH
 	case 2:
 		info->position[0] = SPA_AUDIO_CHANNEL_FL;
 		info->position[1] = SPA_AUDIO_CHANNEL_FR;

pipewire-pulseaudio/src/channelmap.c

@@ -228,7 +228,7 @@ pa_channel_map* pa_channel_map_init_auto(pa_channel_map *m, unsigned channels, p
                     m->map[2] = PA_CHANNEL_POSITION_FRONT_CENTER;
                     m->map[3] = PA_CHANNEL_POSITION_REAR_LEFT;
                     m->map[4] = PA_CHANNEL_POSITION_REAR_RIGHT;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 2:
                     m->map[0] = PA_CHANNEL_POSITION_FRONT_LEFT;
@@ -262,20 +262,20 @@ pa_channel_map* pa_channel_map_init_auto(pa_channel_map *m, unsigned channels, p
                 case 8:
                     m->map[6] = PA_CHANNEL_POSITION_SIDE_LEFT;
                     m->map[7] = PA_CHANNEL_POSITION_SIDE_RIGHT;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 6:
                     m->map[5] = PA_CHANNEL_POSITION_LFE;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 5:
                     m->map[4] = PA_CHANNEL_POSITION_FRONT_CENTER;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 4:
                     m->map[2] = PA_CHANNEL_POSITION_REAR_LEFT;
                     m->map[3] = PA_CHANNEL_POSITION_REAR_RIGHT;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 2:
                     m->map[0] = PA_CHANNEL_POSITION_FRONT_LEFT;
@@ -308,44 +308,44 @@ pa_channel_map* pa_channel_map_init_auto(pa_channel_map *m, unsigned channels, p
                     m->map[15] = PA_CHANNEL_POSITION_TOP_REAR_LEFT;
                     m->map[16] = PA_CHANNEL_POSITION_TOP_REAR_CENTER;
                     m->map[17] = PA_CHANNEL_POSITION_TOP_REAR_RIGHT;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 15:
                     m->map[12] = PA_CHANNEL_POSITION_TOP_FRONT_LEFT;
                     m->map[13] = PA_CHANNEL_POSITION_TOP_FRONT_CENTER;
                     m->map[14] = PA_CHANNEL_POSITION_TOP_FRONT_RIGHT;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 12:
                     m->map[11] = PA_CHANNEL_POSITION_TOP_CENTER;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 11:
                     m->map[9] = PA_CHANNEL_POSITION_SIDE_LEFT;
                     m->map[10] = PA_CHANNEL_POSITION_SIDE_RIGHT;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 9:
                     m->map[8] = PA_CHANNEL_POSITION_REAR_CENTER;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 8:
                     m->map[6] = PA_CHANNEL_POSITION_FRONT_LEFT_OF_CENTER;
                     m->map[7] = PA_CHANNEL_POSITION_FRONT_RIGHT_OF_CENTER;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 6:
                     m->map[4] = PA_CHANNEL_POSITION_REAR_LEFT;
                     m->map[5] = PA_CHANNEL_POSITION_REAR_RIGHT;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 4:
                     m->map[3] = PA_CHANNEL_POSITION_LFE;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 3:
                     m->map[2] = PA_CHANNEL_POSITION_FRONT_CENTER;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 2:
                     m->map[0] = PA_CHANNEL_POSITION_FRONT_LEFT;
@@ -366,20 +366,20 @@ pa_channel_map* pa_channel_map_init_auto(pa_channel_map *m, unsigned channels, p
                 case 8:
                     m->map[6] = PA_CHANNEL_POSITION_REAR_LEFT;
                     m->map[7] = PA_CHANNEL_POSITION_REAR_RIGHT;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 6:
                     m->map[4] = PA_CHANNEL_POSITION_SIDE_LEFT;
                     m->map[5] = PA_CHANNEL_POSITION_SIDE_RIGHT;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 4:
                     m->map[3] = PA_CHANNEL_POSITION_LFE;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 3:
                     m->map[2] = PA_CHANNEL_POSITION_FRONT_CENTER;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
 
                 case 2:
                     m->map[0] = PA_CHANNEL_POSITION_FRONT_LEFT;

pipewire-pulseaudio/src/context.c

@@ -994,7 +994,7 @@ static void node_event_info(void *object, const struct pw_node_info *info)
 			switch (id) {
 			case SPA_PARAM_EnumFormat:
 				clear_node_formats(g);
-				/* fallthrough */
+				SPA_FALLTHROUGH
 			case SPA_PARAM_Props:
 			case SPA_PARAM_Format:
 				do_enum = true;

spa/include/spa/pod/builder.h

@@ -587,6 +587,7 @@ spa_pod_builder_addv(struct spa_pod_builder *builder, va_list args)
 			if (type == 0)
 				goto exit;
 			spa_pod_builder_control(builder, offset, type);
+			SPA_FALLTHROUGH
 		}
 		default:
 			break;

spa/include/spa/pod/parser.h

@@ -420,11 +420,11 @@ do {											\
 	case 'a':									\
 		va_arg(args, void*);							\
 		va_arg(args, void*);							\
-		/* fallthrough */							\
+		SPA_FALLTHROUGH 							\
 	case 'p':									\
 	case 'y':									\
 		va_arg(args, void*);							\
-		/* fallthrough */							\
+		SPA_FALLTHROUGH 							\
 	case 'b':									\
 	case 'I':									\
 	case 'i':									\

spa/include/spa/utils/defs.h

@@ -36,6 +36,30 @@ extern "C" {
 #include <stddef.h>
 #include <stdio.h>
 
+/**
+ * SPA_FALLTHROUGH is an annotation to suppress compiler warnings about switch
+ * cases that fall through without a break or return statement. SPA_FALLTHROUGH
+ * is only needed on cases that have code:
+ *
+ * switch (foo) {
+ *   case 1: // These cases have no code. No fallthrough annotations are needed.
+ *   case 2:
+ *   case 3:
+ *     foo = 4; // This case has code, so a fallthrough annotation is needed:
+ *     SPA_FALLTHROUGH;
+ *   default:
+ *     return foo;
+ * }
+ */
+#if defined(__clang__) && __cplusplus >= 201103L
+   /* clang's fallthrough annotations are only available starting in C++11. */
+#  define SPA_FALLTHROUGH [[clang::fallthrough]];
+#elif defined(__GNUC__) && __GNUC__ >= 7
+ #define SPA_FALLTHROUGH __attribute__ ((fallthrough));
+#else
+#  define SPA_FALLTHROUGH /* FALLTHROUGH */
+#endif
+
 #define SPA_FLAG_MASK(field,mask,flag)	(((field) & (mask)) == (flag))
 #define SPA_FLAG_IS_SET(field,flag)	SPA_FLAG_MASK(field,flag,flag)
 #define SPA_FLAG_SET(field,flag)	((field) |= (flag))

spa/plugins/alsa/acp/alsa-util.c

@@ -1114,7 +1114,7 @@ int pa_alsa_recover_from_poll(snd_pcm_t *pcm, int revents) {
                 }
                 pa_log_warn("Could not recover alsa device from SUSPENDED state, trying to restart PCM");
 	    }
-	    /* Fall through */
+	    SPA_FALLTHROUGH
 
         default:
 

spa/plugins/alsa/acp/channelmap.h

@@ -25,6 +25,8 @@
 extern "C" {
 #endif
 
+#include <spa/utils/defs.h>
+
 #define PA_CHANNELS_MAX	64
 
 #define PA_CHANNEL_MAP_SNPRINT_MAX 336
@@ -161,17 +163,17 @@ static inline pa_channel_map* pa_channel_map_init_auto(pa_channel_map *m, unsign
                 case 8:
                     m->map[6] = PA_CHANNEL_POSITION_SIDE_LEFT;
                     m->map[7] = PA_CHANNEL_POSITION_SIDE_RIGHT;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
                 case 6:
                     m->map[5] = PA_CHANNEL_POSITION_LFE;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
                 case 5:
                     m->map[4] = PA_CHANNEL_POSITION_FRONT_CENTER;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
                 case 4:
                     m->map[2] = PA_CHANNEL_POSITION_REAR_LEFT;
                     m->map[3] = PA_CHANNEL_POSITION_REAR_RIGHT;
-                    /* Fall through */
+                    SPA_FALLTHROUGH
                 case 2:
                     m->map[0] = PA_CHANNEL_POSITION_FRONT_LEFT;
                     m->map[1] = PA_CHANNEL_POSITION_FRONT_RIGHT;

spa/plugins/alsa/acp/meson.build

@@ -18,6 +18,6 @@ acp_lib = static_library(
   'acp',
   acp_sources,
   c_args : acp_c_args,
-  include_directories : [configinc],
+  include_directories : [configinc, spa_inc ],
   dependencies : [ alsa_dep, mathlib, ]
   )

spa/plugins/audioconvert/audioadapter.c

@@ -516,7 +516,7 @@ static int impl_node_send_command(void *object, const struct spa_command *comman
 		break;
 	case SPA_NODE_COMMAND_Suspend:
 		configure_format(this, 0, NULL);
-		/* fallthrough */
+		SPA_FALLTHROUGH
 	case SPA_NODE_COMMAND_Pause:
 		this->started = false;
 		break;

spa/plugins/audioconvert/audioconvert.c

@@ -808,7 +808,7 @@ static int impl_node_send_command(void *object, const struct spa_command *comman
 
 	case SPA_NODE_COMMAND_Suspend:
 		clean_convert(this);
-		/* fallthrough */
+		SPA_FALLTHROUGH
 	case SPA_NODE_COMMAND_Pause:
 		this->started = false;
 		break;

spa/plugins/audioconvert/channelmix.c

@@ -172,17 +172,17 @@ static uint64_t default_mask(uint32_t channels)
 	case 8:
 		mask |= _MASK(RL);
 		mask |= _MASK(RR);
-		/* fallthrough */
+		SPA_FALLTHROUGH
 	case 5:
 	case 6:
 		mask |= _MASK(SL);
 		mask |= _MASK(SR);
 		if ((channels & 1) == 0)
 			mask |= _MASK(LFE);
-		/* fallthrough */
+		SPA_FALLTHROUGH
 	case 3:
 		mask |= _MASK(FC);
-		/* fallthrough */
+		SPA_FALLTHROUGH
 	case 2:
 		mask |= _MASK(FL);
 		mask |= _MASK(FR);
@@ -466,7 +466,7 @@ static int impl_node_send_command(void *object, const struct spa_command *comman
 		this->started = true;
 		break;
 	case SPA_NODE_COMMAND_Suspend:
-		/* fallthrough */
+		SPA_FALLTHROUGH
 	case SPA_NODE_COMMAND_Pause:
 		this->started = false;
 		break;

spa/plugins/audioconvert/fmtconvert.c

@@ -248,7 +248,7 @@ static int impl_node_send_command(void *object, const struct spa_command *comman
 		this->started = true;
 		break;
 	case SPA_NODE_COMMAND_Suspend:
-		/* fallthrough */
+		SPA_FALLTHROUGH
 	case SPA_NODE_COMMAND_Pause:
 		this->started = false;
 		break;

spa/plugins/audioconvert/merger.c

@@ -348,7 +348,7 @@ static int impl_node_send_command(void *object, const struct spa_command *comman
 		this->started = true;
 		break;
 	case SPA_NODE_COMMAND_Suspend:
-		/* fallthrough */
+		SPA_FALLTHROUGH
 	case SPA_NODE_COMMAND_Pause:
 		this->started = false;
 		break;

spa/plugins/audioconvert/resample.c

@@ -262,7 +262,7 @@ static int impl_node_send_command(void *object, const struct spa_command *comman
 		update_rate_match(this);
 		break;
 	case SPA_NODE_COMMAND_Suspend:
-		/* fallthrough */
+		SPA_FALLTHROUGH
 	case SPA_NODE_COMMAND_Pause:
 		resample_reset(&this->resample);
 		this->started = false;

spa/plugins/audioconvert/splitter.c

@@ -330,7 +330,7 @@ static int impl_node_send_command(void *object, const struct spa_command *comman
 		this->started = true;
 		break;
 	case SPA_NODE_COMMAND_Suspend:
-		/* fallthrough */
+		SPA_FALLTHROUGH
 	case SPA_NODE_COMMAND_Pause:
 		this->started = false;
 		break;

src/pipewire/impl-link.c

@@ -229,12 +229,12 @@ static int do_negotiate(struct pw_impl_link *this)
 		case -EIO:
 			current = NULL;
 			res = 0;
-			/* fallthrough */
+			SPA_FALLTHROUGH
 		case 1:
 			break;
 		case 0:
 			res = -EBADF;
-			/* fallthrough */
+			SPA_FALLTHROUGH
 		default:
 			error = spa_aprintf("error get output format: %s", spa_strerror(res));
 			goto error;
@@ -263,12 +263,12 @@ static int do_negotiate(struct pw_impl_link *this)
 		case -EIO:
 			current = NULL;
 			res = 0;
-			/* fallthrough */
+			SPA_FALLTHROUGH
 		case 1:
 			break;
 		case 0:
 			res = -EBADF;
-			/* fallthrough */
+			SPA_FALLTHROUGH
 		default:
 			error = spa_aprintf("error get input format: %s", spa_strerror(res));
 			goto error;