Question

  CC       mips_retval.o
mips_retval.c: In function ‘mips_return_value_location’:
mips_retval.c:249:10: error: this statement may fall through [-Werror=implicit-fallthrough=]
  249 |       if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
      |          ^
mips_retval.c:257:5: note: here
  257 |     case DW_TAG_base_type:
      |     ^~~~
mips_retval.c:261:7: error: this statement may fall through [-Werror=implicit-fallthrough=]
  261 |       {
      |       ^
mips_retval.c:304:5: note: here
  304 |     case DW_TAG_structure_type:
      |     ^~~~
cc1: all warnings being treated as errors

Answer

-      /* Fall through.  */
+         [[fallthrough]];