commit 32db86d558193ad4ad5a00926ce3c350c89eb8df

Author: Joseph Myers <joseph@codesourcery.com>

Date:   Tue Feb 12 10:30:34 2019 +0000

    Add fall-through comments.

    This patch adds fall-through comments in some cases where -Wextra

    produces implicit-fallthrough warnings.

    The patch is non-exhaustive.  Apart from architecture-specific code

    for non-x86_64 architectures, it does not change sunrpc/xdr.c (legacy

    code, probably should have such changes, but left to be dealt with

    separately), or places that already had comments about the

    fall-through but not matching the form expected by

    -Wimplicit-fallthrough=3 (the default level with -Wextra; my

    inclination is to adjust those comments to match rather than

    downgrading to -Wimplicit-fallthrough=1 to allow any comment), or one

    place where I thought the implicit fallthrough was not correct and so

    should be handled separately as a bug fix.  I think the key thing to

    consider in review of this patch is whether the fall-through is indeed

    intended and correct in each place where such a comment is added.

    Tested for x86_64.

            * elf/dl-exception.c (_dl_exception_create_format): Add

            fall-through comments.

            * elf/ldconfig.c (parse_conf_include): Likewise.

            * elf/rtld.c (print_statistics): Likewise.

            * locale/programs/charmap.c (parse_charmap): Likewise.

            * misc/mntent_r.c (__getmntent_r): Likewise.

            * posix/wordexp.c (parse_arith): Likewise.

            (parse_backtick): Likewise.

            * resolv/ns_ttl.c (ns_parse_ttl): Likewise.

            * sysdeps/x86/cpu-features.c (init_cpu_features): Likewise.

            * sysdeps/x86_64/dl-machine.h (elf_machine_rela): Likewise.

diff --git a/elf/dl-exception.c b/elf/dl-exception.c

index 3e8e0ba3f1442005..d24bf30a5cf39bc2 100644

--- a/elf/dl-exception.c

+++ b/elf/dl-exception.c

@@ -123,6 +123,7 @@ _dl_exception_create_format (struct dl_exception *exception, const char *objname

 		  ++p;

 		  break;

 		}

+	      /* Fall through.  */

 	    case 'x':

 	      length += INT_WIDTH / 4;

 	      break;

diff --git a/elf/ldconfig.c b/elf/ldconfig.c

index fbdd814edf59bc77..ed7d9ab0412d93fd 100644

--- a/elf/ldconfig.c

+++ b/elf/ldconfig.c

@@ -1228,6 +1228,7 @@ parse_conf_include (const char *config_file, unsigned int lineno,

     case GLOB_NOSPACE:

       errno = ENOMEM;

+      /* Fall through.  */

     case GLOB_ABORTED:

       if (opt_verbose)

 	error (0, errno, _("%s:%u: cannot read directory %s"),

diff --git a/elf/rtld.c b/elf/rtld.c

index 7f030f75a22c532e..8bb5f548a0ff8eb4 100644

--- a/elf/rtld.c

+++ b/elf/rtld.c

@@ -2734,8 +2734,10 @@ print_statistics (hp_timing_t *rtld_total_timep)

 	{

 	case 3:

 	  *wp++ = *cp++;

+	  /* Fall through.  */

 	case 2:

 	  *wp++ = *cp++;

+	  /* Fall through.  */

 	case 1:

 	  *wp++ = '.';

 	  *wp++ = *cp++;

@@ -2797,8 +2799,10 @@ print_statistics (hp_timing_t *rtld_total_timep)

 	{

 	case 3:

 	  *wp++ = *cp++;

+	  /* Fall through.  */

 	case 2:

 	  *wp++ = *cp++;

+	  /* Fall through.  */

 	case 1:

 	  *wp++ = '.';

 	  *wp++ = *cp++;

diff --git a/locale/programs/charmap.c b/locale/programs/charmap.c

index 2d54dd3c027d11d2..8041a0e5d292f3f5 100644

--- a/locale/programs/charmap.c

+++ b/locale/programs/charmap.c

@@ -713,6 +713,7 @@ only WIDTH definitions are allowed to follow the CHARMAP definition"));

 	      state = 95;

 	      continue;

 	    }

+	  /* Fall through.  */

 	case 96:

 	  if (nowtok != tok_number)

diff --git a/misc/mntent_r.c b/misc/mntent_r.c

index 7bb224f044150ab4..add39d4537eaccb5 100644

--- a/misc/mntent_r.c

+++ b/misc/mntent_r.c

@@ -167,8 +167,10 @@ get_mnt_entry (FILE *stream, struct mntent *mp, char *buffer, int bufsiz)

     {

     case 0:

       mp->mnt_freq = 0;

+      /* Fall through.  */

     case 1:

       mp->mnt_passno = 0;

+      /* Fall through.  */

     case 2:

       break;

     }

diff --git a/posix/wordexp.c b/posix/wordexp.c

index 7548e0329fdeafaa..048a8068544c81fa 100644

--- a/posix/wordexp.c

+++ b/posix/wordexp.c

@@ -799,6 +799,7 @@ parse_arith (char **word, size_t *word_length, size_t *max_length,

 	case '(':

 	  ++paren_depth;

+	  /* Fall through.  */

 	default:

 	  expr = w_addchar (expr, &expr_length, &expr_maxlen, words[*offset]);

 	  if (expr == NULL)

@@ -2127,6 +2128,7 @@ parse_backtick (char **word, size_t *word_length, size_t *max_length,

 	case '\'':

 	  squoting = 1 - squoting;

+	  /* Fall through.  */

 	default:

 	  comm = w_addchar (comm, &comm_length, &comm_maxlen, words[*offset]);

 	  if (comm == NULL)

diff --git a/resolv/ns_ttl.c b/resolv/ns_ttl.c

index 079948790b94b05e..d29d9dc00cfcab2c 100644

--- a/resolv/ns_ttl.c

+++ b/resolv/ns_ttl.c

@@ -113,9 +113,13 @@ ns_parse_ttl(const char *src, u_long *dst) {

 			ch = toupper(ch);

 		switch (ch) {

 		case 'W':  tmp *= 7;

+		  /* Fall through.  */

 		case 'D':  tmp *= 24;

+		  /* Fall through.  */

 		case 'H':  tmp *= 60;

+		  /* Fall through.  */

 		case 'M':  tmp *= 60;

+		  /* Fall through.  */

 		case 'S':  break;

 		default:   goto einval;

 		}

diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c

index 3a02a9c7d08f9603..ade37a9bb3de86cc 100644

--- a/sysdeps/x86/cpu-features.c

+++ b/sysdeps/x86/cpu-features.c

@@ -374,6 +374,7 @@ init_cpu_features (struct cpu_features *cpu_features)

 		 of Core i3/i5/i7 processors if AVX is available.  */

 	      if (!CPU_FEATURES_CPU_P (cpu_features, AVX))

 		break;

+	      /* Fall through.  */

 	    case 0x1a:

 	    case 0x1e:

@@ -401,6 +402,7 @@ init_cpu_features (struct cpu_features *cpu_features)

 	      /* Xeon E7 v3 with stepping >= 4 has working TSX.  */

 	      if (stepping >= 4)

 		break;

+	      /* Fall through.  */

 	    case 0x3c:

 	    case 0x45:

 	    case 0x46:

diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h

index 1942ed5061d18c68..23afb3c05dbe17d6 100644

--- a/sysdeps/x86_64/dl-machine.h

+++ b/sysdeps/x86_64/dl-machine.h

@@ -347,6 +347,7 @@ elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc,

 	  /* Set to symbol size plus addend.  */

 	  value = sym->st_size;

 # endif

+	  /* Fall through.  */

 	case R_X86_64_GLOB_DAT:

 	case R_X86_64_JUMP_SLOT:

 	  *reloc_addr = value + reloc->r_addend;

@@ -460,6 +461,7 @@ elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc,

 	  /* Set to symbol size plus addend.  */

 	  value = sym->st_size;

 #  endif

+	  /* Fall through.  */

 	case R_X86_64_32:

 	  value += reloc->r_addend;

 	  *(unsigned int *) reloc_addr = value;