avoiding 'dead store's reported by clang

[Jim Meyering]

I've run clang on coreutils, and it spotted quite a few dead stores.
These changes remove them:

The chmod.c change below was not completely transparent, since
the new code returns immediately after issuing the root-dev-inode
warning, whereas the old code would fall through, and thus might
have also printed --verbose diagnostics.

Other than that, these are supposed to be "no semantic change" patches.


>From d9cc6dd8b3408b02a7fda0330ec65ef7e0dcddf1 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Mon, 31 Aug 2009 16:37:36 +0200
Subject: [PATCH 1/6] maint: mbsalign.c: remove unnecessary assignment

* gl/lib/mbsalign.c (mbsalign): Remove assignment, the result of which
is never used.
---
 gl/lib/mbsalign.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/gl/lib/mbsalign.c b/gl/lib/mbsalign.c
index 0dfda75..a075747 100644
--- a/gl/lib/mbsalign.c
+++ b/gl/lib/mbsalign.c
@@ -219,7 +219,7 @@ mbsalign (const char *src, char *dest, size_t dest_size,

       dest = mbs_align_pad (dest, dest_end, start_spaces);
       dest = mempcpy(dest, str_to_print, MIN (n_used_bytes, dest_end - dest));
-      dest = mbs_align_pad (dest, dest_end, end_spaces);
+      mbs_align_pad (dest, dest_end, end_spaces);
     }

 mbsalign_cleanup:
--
1.6.4.2.384.g5fc62


>From f480e4a12bf6d82c4e8491cdd82195deaee3652e Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Mon, 31 Aug 2009 17:01:26 +0200
Subject: [PATCH 2/6] maint: tail: remove unnecessary initialization

* src/tail.c (tail_bytes): Don't compute "diff" twice.
---
 src/tail.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/tail.c b/src/tail.c
index ceda5b6..f0dbf5d 100644
--- a/src/tail.c
+++ b/src/tail.c
@@ -1437,7 +1437,7 @@ tail_bytes (const char *pretty_filename, int fd, 
uintmax_t n_bytes,
           off_t diff = end_pos - current_pos;
           /* Be careful here.  The current position may actually be
              beyond the end of the file.  */
-          off_t bytes_remaining = (diff = end_pos - current_pos) < 0 ? 0 : 
diff;
+          off_t bytes_remaining = diff < 0 ? 0 : diff;
           off_t nb = n_bytes;

           if (bytes_remaining <= nb)
--
1.6.4.2.384.g5fc62


>From 563d50611b99e7f9ef0042f33c95a53299bec261 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Mon, 31 Aug 2009 17:05:46 +0200
Subject: [PATCH 3/6] maint: dd: remove unnecessary initialization

* src/dd.c (skip): Remove set-but-never-used variable, soffset.
---
 src/dd.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/src/dd.c b/src/dd.c
index d2f566e..04665f9 100644
--- a/src/dd.c
+++ b/src/dd.c
@@ -1315,14 +1315,13 @@ skip (int fdesc, char const *file, uintmax_t records, 
size_t blocksize,
   else
     {
       int lseek_errno = errno;
-      off_t soffset;

       /* The seek request may have failed above if it was too big
          (> device size, > max file size, etc.)
          Or it may not have been done at all (> OFF_T_MAX).
          Therefore try to seek to the end of the file,
          to avoid redundant reading.  */
-      if ((soffset = skip_via_lseek (file, fdesc, 0, SEEK_END)) >= 0)
+      if ((skip_via_lseek (file, fdesc, 0, SEEK_END)) >= 0)
         {
           /* File is seekable, and we're at the end of it, and
              size <= OFF_T_MAX. So there's no point using read to advance.  */
--
1.6.4.2.384.g5fc62


>From 1af1e3c7c7c74d19b13fb94150541f8489762bcd Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Mon, 31 Aug 2009 17:58:53 +0200
Subject: [PATCH 4/6] maint: shred: remove unnecessary initialization

* src/shred.c (genpattern): Value stored to "n" is never used.
---
 src/shred.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/src/shred.c b/src/shred.c
index 43b6d64..2f31789 100644
--- a/src/shred.c
+++ b/src/shred.c
@@ -677,7 +677,6 @@ genpattern (int *dest, size_t num, struct randint_source *s)
           if ((size_t) k >= n)
             {
               randpasses += n;
-              n = 0;
               break;
             }
           randpasses += k;
--
1.6.4.2.384.g5fc62


>From bf1fc7acdbb5885c8249d4d7cb420812d5d2a37e Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Mon, 31 Aug 2009 18:26:16 +0200
Subject: [PATCH 5/6] maint: chown, chgrp, chmod, chcon: remove unnecessary 
initialization

* src/chown-core.c: Include "ignore-value.h".
(change_file_owner): Don't set "ent" only to ignore it.
* src/chcon.c (process_file): Likewise.
* src/chmod.c: Include "ignore-value.h".
(process_file): Don't set "ent" only to ignore it.
After diagnosing root-dev/ino failure, return false immediately:
Now that we don't set "ent" we must be sure not to use it uninitialized,
and there's no point in issuing --verbose-related output in this case.
---
 src/chcon.c      |    3 ++-
 src/chmod.c      |    5 +++--
 src/chown-core.c |    3 ++-
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/chcon.c b/src/chcon.c
index 2662600..531ed7a 100644
--- a/src/chcon.c
+++ b/src/chcon.c
@@ -22,6 +22,7 @@
 #include "system.h"
 #include "dev-ino.h"
 #include "error.h"
+#include "ignore-value.h"
 #include "quote.h"
 #include "quotearg.h"
 #include "root-dev-ino.h"
@@ -225,7 +226,7 @@ process_file (FTS *fts, FTSENT *ent)
               /* Tell fts not to traverse into this hierarchy.  */
               fts_set (fts, ent, FTS_SKIP);
               /* Ensure that we do not process "/" on the second visit.  */
-              ent = fts_read (fts);
+              ignore_ptr (fts_read (fts));
               return false;
             }
           return true;
diff --git a/src/chmod.c b/src/chmod.c
index 0e39c8b..aeefcc6 100644
--- a/src/chmod.c
+++ b/src/chmod.c
@@ -25,6 +25,7 @@
 #include "dev-ino.h"
 #include "error.h"
 #include "filemode.h"
+#include "ignore-value.h"
 #include "modechange.h"
 #include "quote.h"
 #include "quotearg.h"
@@ -238,8 +239,8 @@ process_file (FTS *fts, FTSENT *ent)
       /* Tell fts not to traverse into this hierarchy.  */
       fts_set (fts, ent, FTS_SKIP);
       /* Ensure that we do not process "/" on the second visit.  */
-      ent = fts_read (fts);
-      ok = false;
+      ignore_ptr (fts_read (fts));
+      return false;
     }

   if (ok)
diff --git a/src/chown-core.c b/src/chown-core.c
index 7e5774e..eb34904 100644
--- a/src/chown-core.c
+++ b/src/chown-core.c
@@ -25,6 +25,7 @@
 #include "system.h"
 #include "chown-core.h"
 #include "error.h"
+#include "ignore-value.h"
 #include "quote.h"
 #include "root-dev-ino.h"
 #include "xfts.h"
@@ -270,7 +271,7 @@ change_file_owner (FTS *fts, FTSENT *ent,
               /* Tell fts not to traverse into this hierarchy.  */
               fts_set (fts, ent, FTS_SKIP);
               /* Ensure that we do not process "/" on the second visit.  */
-              ent = fts_read (fts);
+              ignore_ptr (fts_read (fts));
               return false;
             }
           return true;
--
1.6.4.2.384.g5fc62


>From b53b85d802d58f7fa8415fc5b41b8edf7dd2fc7e Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Mon, 31 Aug 2009 18:39:41 +0200
Subject: [PATCH 6/6] maint: du: remove unnecessary initialization

* src/du.c (main): Don't set "skip_file" unnecessarily.
---
 src/du.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/src/du.c b/src/du.c
index f746c27..24ed5e6 100644
--- a/src/du.c
+++ b/src/du.c
@@ -963,7 +963,6 @@ main (int argc, char **argv)
             {
             case AI_ERR_READ:
               error (0, errno, _("%s: read error"), quote (files_from));
-              skip_file = true;
               continue;

             case AI_ERR_MEM:
--
1.6.4.2.384.g5fc62