avoid warnings about discarding "qualifiers from pointer target type"

Use the new "bad_cast" function or an actual cast-to-"(char *)"
to avoid warnings.
* src/system.h (bad_cast): Define.
* src/chown.c (main):
* src/chroot.c (main):
* src/date.c (main):
* src/du.c (main):
* src/expand.c (stdin_argv):
* src/ls.c (decode_switches):
* src/md5sum.c (main):
* src/paste.c (main):
* src/pr.c (col_sep_string, column_separator, line_separator, main):
* src/sort.c (main):
* src/split.c (main):
* src/tail.c (main):
* src/unexpand.c (stdin_argv):
* src/yes.c (main):

15 files changed, 26 insertions, 20 deletions

diff --git a/src/chown.c b/src/chown.c
index e5740d259..972b281af 100644
--- a/src/chown.c
+++ b/src/chown.c
@@ -312,7 +312,7 @@ main (int argc, char **argv)
 	 empty string so that diagnostics say "ownership :GROUP"
 	 rather than "group GROUP".  */
       if (!chopt.user_name && chopt.group_name)
-        chopt.user_name = "";
+        chopt.user_name = bad_cast ("");
 
       optind++;
     }
diff --git a/src/chroot.c b/src/chroot.c
index 299acbcbf..1eb443c24 100644
--- a/src/chroot.c
+++ b/src/chroot.c
@@ -93,9 +93,9 @@ main (int argc, char **argv)
       /* No command.  Run an interactive shell.  */
       char *shell = getenv ("SHELL");
       if (shell == NULL)
-	shell = "/bin/sh";
+	shell = bad_cast ("/bin/sh");
       argv[0] = shell;
-      argv[1] = "-i";
+      argv[1] = bad_cast ("-i");
       argv[2] = NULL;
     }
   else
diff --git a/src/date.c b/src/date.c
index 3cfcc6265..e94de6013 100644
--- a/src/date.c
+++ b/src/date.c
@@ -385,7 +385,7 @@ main (int argc, char **argv)
 	  /* POSIX says that `date -u' is equivalent to setting the TZ
 	     environment variable, so this option should do nothing other
 	     than setting TZ.  */
-	  if (putenv ("TZ=UTC0") != 0)
+	  if (putenv (bad_cast ("TZ=UTC0")) != 0)
 	    xalloc_die ();
 	  TZSET;
 	  break;
diff --git a/src/du.c b/src/du.c
index fafcea08e..2b0792b37 100644
--- a/src/du.c
+++ b/src/du.c
@@ -674,7 +674,7 @@ main (int argc, char **argv)
   /* If true, display only a total for each argument. */
   bool opt_summarize_only = false;
 
-  cwd_only[0] = ".";
+  cwd_only[0] = bad_cast (".");
   cwd_only[1] = NULL;
 
   initialize_main (&argc, &argv);
diff --git a/src/expand.c b/src/expand.c
index 8efb81b33..87c89152e 100644
--- a/src/expand.c
+++ b/src/expand.c
@@ -76,7 +76,7 @@ static char **file_list;
 /* Default for `file_list' if no files are given on the command line.  */
 static char *stdin_argv[] =
 {
-  "-", NULL
+  (char *) "-", NULL
 };
 
 /* True if we have ever read standard input.  */
diff --git a/src/ls.c b/src/ls.c
index d5bd8d1e0..460e161d1 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -1769,7 +1769,7 @@ decode_switches (int argc, char **argv)
 
 	case FULL_TIME_OPTION:
 	  format = long_format;
-	  time_style_option = "full-iso";
+	  time_style_option = bad_cast ("full-iso");
 	  break;
 
 	case COLOR_OPTION:
@@ -1887,7 +1887,7 @@ decode_switches (int argc, char **argv)
 
       if (! style)
 	if (! (style = getenv ("TIME_STYLE")))
-	  style = "locale";
+	  style = bad_cast ("locale");
 
       while (strncmp (style, posix_prefix, sizeof posix_prefix - 1) == 0)
 	{
diff --git a/src/md5sum.c b/src/md5sum.c
index d31a780bf..969cc7175 100644
--- a/src/md5sum.c
+++ b/src/md5sum.c
@@ -686,7 +686,7 @@ main (int argc, char **argv)
     binary = 0;
 
   if (optind == argc)
-    argv[argc++] = "-";
+    argv[argc++] = bad_cast ("-");
 
   for (; optind < argc; ++optind)
     {
diff --git a/src/paste.c b/src/paste.c
index 9dee94aa4..f04bcc3b1 100644
--- a/src/paste.c
+++ b/src/paste.c
@@ -496,7 +496,7 @@ main (int argc, char **argv)
     }
 
   if (optind == argc)
-    argv[argc++] = "-";
+    argv[argc++] = bad_cast ("-");
 
   if (collapse_escapes (delim_arg))
     {
diff --git a/src/pr.c b/src/pr.c
index 0d8845fe6..044bb5609 100644
--- a/src/pr.c
+++ b/src/pr.c
@@ -691,10 +691,10 @@ static bool use_col_separator = false;
 /* String used to separate columns if the -S option has been specified.
    Default without -S but together with one of the column options
    -a|COLUMN|-m is a `space' and with the -J option a `tab'. */
-static char *col_sep_string = "";
+static char *col_sep_string = (char *) "";
 static int col_sep_length = 0;
-static char *column_separator = " ";
-static char *line_separator = "\t";
+static char *column_separator = (char *) " ";
+static char *line_separator = (char *) "\t";
 
 /* Number of separator characters waiting to be printed as soon as we
    know that we have any input remaining to be printed. */
@@ -1030,7 +1030,7 @@ main (int argc, char **argv)
 	case 'S':
 	  old_s = false;
 	  /* Reset an additional input of -s, -S dominates -s */
-	  col_sep_string = "";
+	  col_sep_string = bad_cast ("");
 	  col_sep_length = 0;
 	  use_col_separator = true;
 	  if (optarg)
diff --git a/src/sort.c b/src/sort.c
index 43c28fc84..fe58908b9 100644
--- a/src/sort.c
+++ b/src/sort.c
@@ -3381,7 +3381,7 @@ main (int argc, char **argv)
 
   if (nfiles == 0)
     {
-      static char *minus = "-";
+      static char *minus = (char *) "-";
       nfiles = 1;
       free (files);
       files = &minus;
diff --git a/src/split.c b/src/split.c
index be182eff6..1d8a94ca7 100644
--- a/src/split.c
+++ b/src/split.c
@@ -401,8 +401,8 @@ main (int argc, char **argv)
 
   /* Parse command line options.  */
 
-  infile = "-";
-  outbase = "x";
+  infile = bad_cast ( "-");
+  outbase = bad_cast ("x");
 
   while (1)
     {
diff --git a/src/system.h b/src/system.h
index 8577d4464..ee0d25cd9 100644
--- a/src/system.h
+++ b/src/system.h
@@ -631,3 +631,9 @@ timetostr (time_t t, char *buf)
 	  ? imaxtostr (t, buf)
 	  : umaxtostr (t, buf));
 }
+
+static inline char *
+bad_cast (char const *s)
+{
+  return (char *) s;
+}
diff --git a/src/tail.c b/src/tail.c
index 6ad6d4330..fe3460054 100644
--- a/src/tail.c
+++ b/src/tail.c
@@ -1629,7 +1629,7 @@ main (int argc, char **argv)
     }
   else
     {
-      static char *dummy_stdin = "-";
+      static char *dummy_stdin = (char *) "-";
       n_files = 1;
       file = &dummy_stdin;
 
diff --git a/src/unexpand.c b/src/unexpand.c
index 5a2d0cdeb..d73d101d4 100644
--- a/src/unexpand.c
+++ b/src/unexpand.c
@@ -80,7 +80,7 @@ static char **file_list;
 /* Default for `file_list' if no files are given on the command line.  */
 static char *stdin_argv[] =
 {
-  "-", NULL
+  (char *) "-", NULL
 };
 
 /* True if we have ever read standard input.  */
diff --git a/src/yes.c b/src/yes.c
index e2a58445f..cfd06079f 100644
--- a/src/yes.c
+++ b/src/yes.c
@@ -75,7 +75,7 @@ main (int argc, char **argv)
   if (argc <= optind)
     {
       optind = argc;
-      argv[argc++] = "y";
+      argv[argc++] = bad_cast ("y");
     }
 
   for (;;)