osdep: add MP_FALLTHROUGH

osdep/compiler.h

@@ -6,9 +6,11 @@
 #ifdef __GNUC__
 #define PRINTF_ATTRIBUTE(a1, a2) __attribute__ ((format(printf, a1, a2)))
 #define MP_NORETURN __attribute__((noreturn))
+#define MP_FALLTHROUGH __attribute__((fallthrough))
 #else
 #define PRINTF_ATTRIBUTE(a1, a2)
 #define MP_NORETURN
+#define MP_FALLTHROUGH do {} while (0)
 #endif
 
 // Broken crap with __USE_MINGW_ANSI_STDIO

video/out/gpu/shader_cache.c

@@ -699,7 +699,7 @@ static void add_uniforms(struct gl_shader_cache *sc, bstr *dst)
         case RA_VARTYPE_INT:
         case RA_VARTYPE_FLOAT:
             assert(sc->ra->caps & RA_CAP_GLOBAL_UNIFORM);
-            // fall through
+            MP_FALLTHROUGH;
         case RA_VARTYPE_TEX:
             // Vulkan requires explicitly assigning the bindings in the shader
             // source. For OpenGL it's optional, but requires higher GL version

video/out/opengl/context.c

@@ -261,7 +261,7 @@ bool ra_gl_ctx_submit_frame(struct ra_swapchain *sw, const struct vo_frame *fram
     case FLUSH_AUTO:
         if (frame->display_synced)
             break;
-        // fall through
+        MP_FALLTHROUGH;
     case FLUSH_YES:
         gl->Flush();
     }

video/out/vo_gpu_next.c

@@ -1859,7 +1859,7 @@ static void update_render_options(struct vo *vo)
 #else
         MP_ERR(p, "Error diffusion dithering is not implemented.\n");
 #endif
-        // fall through
+        MP_FALLTHROUGH;
     case DITHER_ORDERED:
     case DITHER_FRUIT:
         p->params.dither_params = &p->dither;