maint: quote 'like this' or "like this", not `like this'

This is in response to a recent change in the GNU coding standards,
which now suggest quoting 'like this' or "like this", instead of
`like this' or ``like this''.
* HACKING, NEWS, README, README-hacking, TODO, doc/diagmeet.note:
* doc/diffutils.texi, ms/config.bat, ms/config.site:
* src/analyze.c, src/cmp.c, src/context.c, src/diff.c:
* src/diff.h, src/diff3.c, src/dir.c, src/ifdef.c, src/io.c:
* src/sdiff.c, src/side.c, src/system.h, src/util.c:
* tests/help-version:
Quote 'like this' or "like this" in commentary.
* cfg.mk (old_NEWS_hash): Adjust to reflect new NEWS quoting.
* man/help2man: Update to 1.40.4 version, with quoting fixed as above.
* po/en.po: Remove translation involving `, as it's no longer needed.
* src/cmp.c (try_help, specify_ignore_initial, usage, main):
* src/diff.c (main, try_help, option_help_msgid, specify_value)
(compare_files):
* src/diff3.c (main, try_help, option_help_msgid, usage)
(read_diff):
* src/dir.c (compare_names):
* src/sdiff.c (try_help, usage, check_child_status, main):
* src/util.c (finish_output):
* tests/help-version:
Quote 'like this' in output.

13 files changed, 91 insertions, 91 deletions

diff --git a/src/analyze.c b/src/analyze.c
index 124ded5..0e61a82 100644
--- a/src/analyze.c
+++ b/src/analyze.c
@@ -38,7 +38,7 @@
 
    A line which is discarded will not be considered by the actual
    comparison algorithm; it will be as if that line were not in the file.
-   The file's `realindexes' table maps virtual line numbers
+   The file's 'realindexes' table maps virtual line numbers
    (which don't count the discarded lines) into real line numbers;
    this is how the actual comparison algorithm produces results
    that are comprehensible when the discarded lines are counted.
@@ -251,7 +251,7 @@ discard_confusing_lines (struct file_data filevec[])
    We do something when a run of changed lines include a
    line at one end and have an excluded, identical line at the other.
    We are free to choose which identical line is included.
-   `compareseq' usually chooses the one at the beginning,
+   'compareseq' usually chooses the one at the beginning,
    but usually it is cleaner to consider the following identical line
    to be the "change".  */
 
@@ -595,7 +595,7 @@ diff_2_files (struct comparison *cmp)
       shift_boundaries (cmp->file);
 
       /* Get the results of comparison in the form of a chain
-	 of `struct change's -- an edit script.  */
+	 of 'struct change's -- an edit script.  */
 
       if (output_style == OUTPUT_ED)
 	script = build_reverse_script (cmp->file);
diff --git a/src/cmp.c b/src/cmp.c
index 53ae791..1387ec1 100644
--- a/src/cmp.c
+++ b/src/cmp.c
@@ -36,7 +36,7 @@
 #include <binary-io.h>
 #include <xstrtol.h>
 
-/* The official name of this program (e.g., no `g' prefix).  */
+/* The official name of this program (e.g., no 'g' prefix).  */
 #define PROGRAM_NAME "cmp"
 
 #define AUTHORS \
@@ -115,7 +115,7 @@ try_help (char const *reason_msgid, char const *operand)
   if (reason_msgid)
     error (0, 0, _(reason_msgid), operand);
   error (EXIT_TROUBLE, 0,
-	 _("Try `%s --help' for more information."), program_name);
+	 _("Try '%s --help' for more information."), program_name);
   abort ();
 }
 
@@ -134,7 +134,7 @@ specify_ignore_initial (int f, char **argptr, char delimiter)
   if (! (e == LONGINT_OK
 	 || (e == LONGINT_INVALID_SUFFIX_CHAR && **argptr == delimiter))
       || TYPE_MAXIMUM (off_t) < val)
-    try_help ("invalid --ignore-initial value `%s'", arg);
+    try_help ("invalid --ignore-initial value '%s'", arg);
   if (ignore_initial[f] < val)
     ignore_initial[f] = val;
 }
@@ -191,7 +191,7 @@ Mandatory arguments to long options are mandatory for short options too.\n\
 	  _("SKIP values may be followed by the following multiplicative suffixes:\n\
 kB 1000, K 1024, MB 1,000,000, M 1,048,576,\n\
 GB 1,000,000,000, G 1,073,741,824, and so on for T, P, E, Z, Y."),
-	  _("If a FILE is `-' or missing, read standard input."),
+	  _("If a FILE is '-' or missing, read standard input."),
 	  _("Exit status is 0 if inputs are the same, 1 if different, 2 if trouble."));
   emit_bug_reporting_address ();
 }
@@ -237,7 +237,7 @@ main (int argc, char **argv)
 	{
 	  uintmax_t n;
 	  if (xstrtoumax (optarg, 0, 0, &n, valid_suffixes) != LONGINT_OK)
-	    try_help ("invalid --bytes value `%s'", optarg);
+	    try_help ("invalid --bytes value '%s'", optarg);
 	  if (n < bytes)
 	    bytes = n;
 	}
@@ -263,7 +263,7 @@ main (int argc, char **argv)
       }
 
   if (optind == argc)
-    try_help ("missing operand after `%s'", argv[argc - 1]);
+    try_help ("missing operand after '%s'", argv[argc - 1]);
 
   file[0] = argv[optind++];
   file[1] = optind < argc ? argv[optind++] : "-";
@@ -275,7 +275,7 @@ main (int argc, char **argv)
     }
 
   if (optind < argc)
-    try_help ("extra operand `%s'", argv[optind]);
+    try_help ("extra operand '%s'", argv[optind]);
 
   for (f = 0; f < 2; f++)
     {
@@ -370,8 +370,8 @@ main (int argc, char **argv)
   return exit_status;
 }
 
-/* Compare the two files already open on `file_desc[0]' and `file_desc[1]',
-   using `buffer[0]' and `buffer[1]'.
+/* Compare the two files already open on 'file_desc[0]' and 'file_desc[1]',
+   using 'buffer[0]' and 'buffer[1]'.
    Return EXIT_SUCCESS if identical, EXIT_FAILURE if different,
    >1 if error.  */
 
@@ -383,7 +383,7 @@ cmp (void)
   uintmax_t remaining = bytes;	/* Remaining number of bytes to compare.  */
   size_t read0, read1;		/* Number of bytes read from each file. */
   size_t first_diff;		/* Offset (0...) in buffers of 1st diff. */
-  size_t smaller;		/* The lesser of `read0' and `read1'. */
+  size_t smaller;		/* The lesser of 'read0' and 'read1'. */
   word *buffer0 = buffer[0];
   word *buffer1 = buffer[1];
   char *buf0 = (char *) buffer0;
diff --git a/src/context.c b/src/context.c
index bd1c981..b73d5c3 100644
--- a/src/context.c
+++ b/src/context.c
@@ -158,7 +158,7 @@ print_context_function (FILE *out, char const *function)
 
 /* Print a portion of an edit script in context format.
    HUNK is the beginning of the portion to be printed.
-   The end is marked by a `link' that has been nulled out.
+   The end is marked by a 'link' that has been nulled out.
 
    Prints out lines from both files, and precedes each
    line with the appropriate flag-character.  */
@@ -288,7 +288,7 @@ print_unidiff_number_range (struct file_data const *file, lin a, lin b)
 
 /* Print a portion of an edit script in unidiff format.
    HUNK is the beginning of the portion to be printed.
-   The end is marked by a `link' that has been nulled out.
+   The end is marked by a 'link' that has been nulled out.
 
    Prints out lines from both files, and precedes each
    line with the appropriate flag-character.  */
@@ -392,7 +392,7 @@ pr_unidiff_hunk (struct change *hunk)
 
 /* Scan a (forward-ordered) edit script for the first place that more than
    2*CONTEXT unchanged lines appear, and return a pointer
-   to the `struct change' for the last change before those lines.  */
+   to the 'struct change' for the last change before those lines.  */
 
 static struct change * _GL_ATTRIBUTE_PURE
 find_hunk (struct change *start)
@@ -430,7 +430,7 @@ find_hunk (struct change *start)
   return prev;
 }
 
-/* Set the `ignore' flag properly in each change in SCRIPT.
+/* Set the 'ignore' flag properly in each change in SCRIPT.
    It should be 1 if all the lines inserted or deleted in that change
    are ignorable lines.  */
 
@@ -458,7 +458,7 @@ mark_ignorable (struct change *script)
 }
 
 /* Find the last function-header line in LINBUF prior to line number LINENUM.
-   This is a line containing a match for the regexp in `function_regexp'.
+   This is a line containing a match for the regexp in 'function_regexp'.
    Return the address of the text, or NULL if no function-header is found.  */
 
 static char const *
diff --git a/src/diff.c b/src/diff.c
index 0911131..972d84d 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -42,7 +42,7 @@
 #include <xreadlink.h>
 #include <binary-io.h>
 
-/* The official name of this program (e.g., no `g' prefix).  */
+/* The official name of this program (e.g., no 'g' prefix).  */
 #define PROGRAM_NAME "diff"
 
 #define AUTHORS \
@@ -59,9 +59,9 @@
 struct regexp_list
 {
   char *regexps;	/* chars representing disjunction of the regexps */
-  size_t len;		/* chars used in `regexps' */
-  size_t size;		/* size malloc'ed for `regexps'; 0 if not malloc'ed */
-  bool multiple_regexps;/* Does `regexps' represent a disjunction?  */
+  size_t len;		/* chars used in 'regexps' */
+  size_t size;		/* size malloc'ed for 'regexps'; 0 if not malloc'ed */
+  bool multiple_regexps;/* Does 'regexps' represent a disjunction?  */
   struct re_pattern_buffer *buf;
 };
 
@@ -94,13 +94,13 @@ enum { binary = true };
 
 /* When comparing directories, if a file appears only in one
    directory, treat it as present but empty in the other (-N).
-   Then `patch' would create the file with appropriate contents.  */
+   Then 'patch' would create the file with appropriate contents.  */
 static bool new_file;
 
 /* When comparing directories, if a file appears only in the second
    directory of the two, treat it as present but empty in the other
    (--unidirectional-new-file).
-   Then `patch' would create the file with appropriate contents.  */
+   Then 'patch' would create the file with appropriate contents.  */
 static bool unidirectional_new_file;
 
 /* Report files compared that are the same (-s).
@@ -340,7 +340,7 @@ main (int argc, char **argv)
 	      {
 		numval = strtoumax (optarg, &numend, 10);
 		if (*numend)
-		  try_help ("invalid context length `%s'", optarg);
+		  try_help ("invalid context length '%s'", optarg);
 		if (LIN_MAX < numval)
 		  numval = LIN_MAX;
 	      }
@@ -515,7 +515,7 @@ main (int argc, char **argv)
 	case 'W':
 	  numval = strtoumax (optarg, &numend, 10);
 	  if (! (0 < numval && numval <= SIZE_MAX) || *numend)
-	    try_help ("invalid width `%s'", optarg);
+	    try_help ("invalid width '%s'", optarg);
 	  if (width != numval)
 	    {
 	      if (width)
@@ -544,7 +544,7 @@ main (int argc, char **argv)
 	case HORIZON_LINES_OPTION:
 	  numval = strtoumax (optarg, &numend, 10);
 	  if (*numend)
-	    try_help ("invalid horizon length `%s'", optarg);
+	    try_help ("invalid horizon length '%s'", optarg);
 	  horizon_lines = MAX (horizon_lines, MIN (numval, LIN_MAX));
 	  break;
 
@@ -599,7 +599,7 @@ main (int argc, char **argv)
 	case TABSIZE_OPTION:
 	  numval = strtoumax (optarg, &numend, 10);
 	  if (! (0 < numval && numval <= SIZE_MAX) || *numend)
-	    try_help ("invalid tabsize `%s'", optarg);
+	    try_help ("invalid tabsize '%s'", optarg);
 	  if (tabsize != numval)
 	    {
 	      if (tabsize)
@@ -758,9 +758,9 @@ main (int argc, char **argv)
 	  if (argc - optind != 2)
 	    {
 	      if (argc - optind < 2)
-		try_help ("missing operand after `%s'", argv[argc - 1]);
+		try_help ("missing operand after '%s'", argv[argc - 1]);
 	      else
-		try_help ("extra operand `%s'", argv[optind + 2]);
+		try_help ("extra operand '%s'", argv[optind + 2]);
 	    }
 
 	  exit_status = compare_files (NULL, argv[optind], argv[optind + 1]);
@@ -840,7 +840,7 @@ try_help (char const *reason_msgid, char const *operand)
 {
   if (reason_msgid)
     error (0, 0, _(reason_msgid), operand);
-  error (EXIT_TROUBLE, 0, _("Try `%s --help' for more information."),
+  error (EXIT_TROUBLE, 0, _("Try '%s --help' for more information."),
 	 program_name);
   abort ();
 }
@@ -876,7 +876,7 @@ static char const * const option_help_msgid[] = {
   N_("-T, --initial-tab             make tabs line up by prepending a tab"),
   N_("    --tabsize=NUM             tab stops every NUM (default 8) print columns"),
   N_("    --suppress-blank-empty    suppress space or tab before empty output lines"),
-  N_("-l, --paginate                pass output through `pr' to paginate it"),
+  N_("-l, --paginate                pass output through 'pr' to paginate it"),
   "",
   N_("-r, --recursive                 recursively compare any subdirectories found"),
   N_("    --no-dereference            don't follow symbolic links"),
@@ -906,13 +906,13 @@ static char const * const option_help_msgid[] = {
   N_("    --binary                    read and write data in binary mode"),
 #endif
   "",
-  N_("-D, --ifdef=NAME                output merged file with `#ifdef NAME' diffs"),
+  N_("-D, --ifdef=NAME                output merged file with '#ifdef NAME' diffs"),
   N_("    --GTYPE-group-format=GFMT   format GTYPE input groups with GFMT"),
   N_("    --line-format=LFMT          format all input lines with LFMT"),
   N_("    --LTYPE-line-format=LFMT    format LTYPE input lines with LFMT"),
   N_("  These format options provide fine-grained control over the output\n"
      "    of diff, generalizing -D/--ifdef."),
-  N_("  LTYPE is `old', `new', or `unchanged'.  GTYPE is LTYPE or `changed'."),
+  N_("  LTYPE is 'old', 'new', or 'unchanged'.  GTYPE is LTYPE or 'changed'."),
   N_("  GFMT (only) may contain:\n\
     %<  lines from FILE1\n\
     %>  lines from FILE2\n\
@@ -942,9 +942,9 @@ static char const * const option_help_msgid[] = {
   N_("    --help               display this help and exit"),
   N_("-v, --version            output version information and exit"),
   "",
-  N_("FILES are `FILE1 FILE2' or `DIR1 DIR2' or `DIR FILE...' or `FILE... DIR'."),
+  N_("FILES are 'FILE1 FILE2' or 'DIR1 DIR2' or 'DIR FILE...' or 'FILE... DIR'."),
   N_("If --from-file or --to-file is given, there are no restrictions on FILE(s)."),
-  N_("If a FILE is `-', read standard input."),
+  N_("If a FILE is '-', read standard input."),
   N_("Exit status is 0 if inputs are the same, 1 if different, 2 if trouble."),
   0
 };
@@ -989,7 +989,7 @@ specify_value (char const **var, char const *value, char const *option)
 {
   if (*var && ! STREQ (*var, value))
     {
-      error (0, 0, _("conflicting %s option value `%s'"), option, value);
+      error (0, 0, _("conflicting %s option value '%s'"), option, value);
       try_help (NULL, NULL);
     }
   *var = value;
@@ -1191,7 +1191,7 @@ compare_files (struct comparison const *parent,
 	= find_dir_file_pathname (dir, last_component (fnm));
 
       if (STREQ (fnm, "-"))
-	fatal ("cannot compare `-' to a directory");
+	fatal ("cannot compare '-' to a directory");
 
       if ((no_dereference_symlinks
 	   ? lstat (filename, &cmp.file[dir_arg].stat)
diff --git a/src/diff.h b/src/diff.h
index 05029a3..4b6595c 100644
--- a/src/diff.h
+++ b/src/diff.h
@@ -61,7 +61,7 @@ enum output_style
   /* Output the differences in a unified context diff format (-u).  */
   OUTPUT_UNIFIED,
 
-  /* Output the differences as commands suitable for `ed' (-e).  */
+  /* Output the differences as commands suitable for 'ed' (-e).  */
   OUTPUT_ED,
 
   /* Output the diff as a forward ed script (-f).  */
@@ -139,7 +139,7 @@ XTERN bool ignore_file_name_case;
    (--no-dereference).  */
 XTERN bool no_dereference_symlinks;
 
-/* File labels for `-c' output headers (--label).  */
+/* File labels for '-c' output headers (--label).  */
 XTERN char *file_label[2];
 
 /* Regexp to identify function-header lines (-F).  */
@@ -215,8 +215,8 @@ XTERN bool minimal;
 /* The strftime format to use for time strings.  */
 XTERN char const *time_format;
 
-/* The result of comparison is an "edit script": a chain of `struct change'.
-   Each `struct change' represents one place where some lines are deleted
+/* The result of comparison is an "edit script": a chain of 'struct change'.
+   Each 'struct change' represents one place where some lines are deleted
    and some are inserted.
 
    LINE0 and LINE1 are the first affected lines in the two files (origin 0).
diff --git a/src/diff3.c b/src/diff3.c
index 7d8a9a5..3b01071 100644
--- a/src/diff3.c
+++ b/src/diff3.c
@@ -34,7 +34,7 @@
 #include <xalloc.h>
 #include <xfreopen.h>
 
-/* The official name of this program (e.g., no `g' prefix).  */
+/* The official name of this program (e.g., no 'g' prefix).  */
 #define PROGRAM_NAME "diff3"
 
 #define AUTHORS \
@@ -158,7 +158,7 @@ static bool overlap_only;
 /* If nonzero, show information for DIFF_2ND diffs.  */
 static bool show_2nd;
 
-/* If nonzero, include `:wq' at the end of the script
+/* If nonzero, include ':wq' at the end of the script
    to write out the file being edited.   */
 static bool finalwrite;
 
@@ -315,9 +315,9 @@ main (int argc, char **argv)
   if (argc - optind != 3)
     {
       if (argc - optind < 3)
-	try_help ("missing operand after `%s'", argv[argc - 1]);
+	try_help ("missing operand after '%s'", argv[argc - 1]);
       else
-	try_help ("extra operand `%s'", argv[optind + 3]);
+	try_help ("extra operand '%s'", argv[optind + 3]);
     }
 
   file = &argv[optind];
@@ -350,7 +350,7 @@ main (int argc, char **argv)
 	 file instead.  */
       common = 3 - common;
       if (STREQ (file[0], "-") || STREQ (file[common], "-"))
-	fatal ("`-' specified for more than one input file");
+	fatal ("'-' specified for more than one input file");
     }
 
   mapping[0] = 0;
@@ -411,7 +411,7 @@ try_help (char const *reason_msgid, char const *operand)
   if (reason_msgid)
     error (0, 0, _(reason_msgid), operand);
   error (EXIT_TROUBLE, 0,
-	 _("Try `%s --help' for more information."), program_name);
+	 _("Try '%s --help' for more information."), program_name);
   abort ();
 }
 
@@ -433,7 +433,7 @@ static char const * const option_help_msgid[] = {
   N_("-3, --easy-only             like -e, but incorporate only nonoverlapping changes"),
   N_("-x, --overlap-only          like -e, but incorporate only overlapping changes"),
   N_("-X                          like -x, but bracket conflicts"),
-  N_("-i                          append `w' and `q' commands to ed scripts"),
+  N_("-i                          append 'w' and 'q' commands to ed scripts"),
   "",
   N_("-m, --merge                 output actual merged file, according to\n"
      "                                -A if no other options are given"),
@@ -478,7 +478,7 @@ Finally, the -m (--merge) option causes diff3 to do the merge internally\n\
 and output the actual merged file.  For unusual input, this is more\n\
 robust than using ed.\n"), stdout);
   printf ("\n%s\n%s\n",
-	  _("If a FILE is `-', read standard input."),
+	  _("If a FILE is '-', read standard input."),
 	  _("Exit status is 0 if successful, 1 if conflicts, 2 if trouble."));
   emit_bug_reporting_address ();
 }
@@ -1293,12 +1293,12 @@ read_diff (char const *filea,
   if (EXIT_TROUBLE <= status)
     error (EXIT_TROUBLE, werrno,
 	   _(status == 126
-	     ? "subsidiary program `%s' could not be invoked"
+	     ? "subsidiary program '%s' could not be invoked"
 	     : status == 127
-	     ? "subsidiary program `%s' not found"
+	     ? "subsidiary program '%s' not found"
 	     : status == INT_MAX
-	     ? "subsidiary program `%s' failed"
-	     : "subsidiary program `%s' failed (exit status %d)"),
+	     ? "subsidiary program '%s' failed"
+	     : "subsidiary program '%s' failed (exit status %d)"),
 	   diff_program, status);
 
   return diff_result + total;
@@ -1493,7 +1493,7 @@ undotlines (FILE *outputfile, bool leading_dot, long int start, lin num)
    around the problems involved with changing line numbers in an ed
    script.
 
-   As in `output_diff3', the variable MAPPING maps from file number
+   As in 'output_diff3', the variable MAPPING maps from file number
    according to the argument list to file number according to the diff
    passed.  All files listed below are in terms of the argument list.
    REV_MAPPING is the inverse of MAPPING.
diff --git a/src/dir.c b/src/dir.c
index 2fbaf4b..57134c7 100644
--- a/src/dir.c
+++ b/src/dir.c
@@ -85,7 +85,7 @@ dir_read (struct file_data const *dir, struct dirdata *dirdata)
       dirdata->data = data = xmalloc (data_alloc);
 
       /* Read the directory entries, and insert the subfiles
-	 into the `data' table.  */
+	 into the 'data' table.  */
 
       while ((errno = 0, (next = readdir (reading)) != 0))
 	{
@@ -126,7 +126,7 @@ dir_read (struct file_data const *dir, struct dirdata *dirdata)
 #endif
     }
 
-  /* Create the `names' table from the `data' table.  */
+  /* Create the 'names' table from the 'data' table.  */
   if (PTRDIFF_MAX / sizeof *names - 1 <= nnames)
     xalloc_die ();
   dirdata->names = names = xmalloc ((nnames + 1) * sizeof *names);
@@ -155,7 +155,7 @@ compare_names (char const *name1, char const *name2)
 	r = strcoll (name1, name2);
       if (errno)
 	{
-	  error (0, errno, _("cannot compare file names `%s' and `%s'"),
+	  error (0, errno, _("cannot compare file names '%s' and '%s'"),
 		 name1, name2);
 	  longjmp (failed_locale_specific_sorting, 1);
 	}
@@ -235,7 +235,7 @@ diff_dirs (struct comparison const *cmp,
 	qsort (names[i], dirdata[i].nnames, sizeof *dirdata[i].names,
 	       compare_names_for_qsort);
 
-      /* If `-S name' was given, and this is the topmost level of comparison,
+      /* If '-S name' was given, and this is the topmost level of comparison,
 	 ignore all file names less than the specified starting name.  */
 
       if (starting_file && ! cmp->parent)
diff --git a/src/ifdef.c b/src/ifdef.c
index 7251085..94f170b 100644
--- a/src/ifdef.c
+++ b/src/ifdef.c
@@ -132,7 +132,7 @@ format_group (register FILE *out, char const *format, char endchar,
 	    break;
 
 	  case '(':
-	    /* Print if-then-else format e.g. `%(n=1?thenpart:elsepart)'.  */
+	    /* Print if-then-else format e.g. '%(n=1?thenpart:elsepart)'.  */
 	    {
 	      int i;
 	      uintmax_t value[2];
diff --git a/src/io.c b/src/io.c
index 722cdf0..5a631a5 100644
--- a/src/io.c
+++ b/src/io.c
@@ -57,10 +57,10 @@ static size_t nbuckets;
    The number of an equivalence class is its index in this array.  */
 static struct equivclass *equivs;
 
-/* Index of first free element in the array `equivs'.  */
+/* Index of first free element in the array 'equivs'.  */
 static lin equivs_index;
 
-/* Number of elements allocated in the array `equivs'.  */
+/* Number of elements allocated in the array 'equivs'.  */
 static lin equivs_alloc;
 
 /* Read a block of data into a file buffer, checking for EOF and error.  */
diff --git a/src/sdiff.c b/src/sdiff.c
index a77b36b..e1bb117 100644
--- a/src/sdiff.c
+++ b/src/sdiff.c
@@ -35,7 +35,7 @@
 #include <version-etc.h>
 #include <xalloc.h>
 
-/* The official name of this program (e.g., no `g' prefix).  */
+/* The official name of this program (e.g., no 'g' prefix).  */
 #define PROGRAM_NAME "sdiff"
 
 #define AUTHORS \
@@ -91,7 +91,7 @@ static int const sigs[] = {
 };
 
 #if HAVE_SIGACTION
-  /* Prefer `sigaction' if available, since `signal' can lose signals.  */
+  /* Prefer 'sigaction' if available, since 'signal' can lose signals.  */
   static struct sigaction initial_action[NUM_SIGS];
 # define initial_handler(i) (initial_action[i].sa_handler)
   static void signal_handler (int, void (*) (int));
@@ -152,7 +152,7 @@ try_help (char const *reason_msgid, char const *operand)
 {
   if (reason_msgid)
     error (0, 0, _(reason_msgid), operand);
-  error (EXIT_TROUBLE, 0, _("Try `%s --help' for more information."),
+  error (EXIT_TROUBLE, 0, _("Try '%s --help' for more information."),
 	 program_name);
   abort ();
 }
@@ -213,7 +213,7 @@ Mandatory arguments to long options are mandatory for short options too.\n\
     else
       putchar ('\n');
   printf ("\n%s\n%s\n",
-	  _("If a FILE is `-', read standard input."),
+	  _("If a FILE is '-', read standard input."),
 	  _("Exit status is 0 if inputs are the same, 1 if different, 2 if trouble."));
   emit_bug_reporting_address ();
 }
@@ -269,12 +269,12 @@ check_child_status (int werrno, int wstatus, int max_ok_status,
     {
       error (0, werrno,
 	     _(status == 126
-	       ? "subsidiary program `%s' could not be invoked"
+	       ? "subsidiary program '%s' could not be invoked"
 	       : status == 127
-	       ? "subsidiary program `%s' not found"
+	       ? "subsidiary program '%s' not found"
 	       : status == INT_MAX
-	       ? "subsidiary program `%s' failed"
-	       : "subsidiary program `%s' failed (exit status %d)"),
+	       ? "subsidiary program '%s' failed"
+	       : "subsidiary program '%s' failed (exit status %d)"),
 	     subsidiary_program, status);
       exiterr ();
     }
@@ -559,9 +559,9 @@ main (int argc, char *argv[])
   if (argc - optind != 2)
     {
       if (argc - optind < 2)
-	try_help ("missing operand after `%s'", argv[argc - 1]);
+	try_help ("missing operand after '%s'", argv[argc - 1]);
       else
-	try_help ("extra operand `%s'", argv[optind + 2]);
+	try_help ("extra operand '%s'", argv[optind + 2]);
     }
 
   if (! output)
@@ -706,7 +706,7 @@ main (int argc, char *argv[])
 	exit (WEXITSTATUS (wstatus));
       }
     }
-  return EXIT_SUCCESS;			/* Fool `-Wall'.  */
+  return EXIT_SUCCESS;			/* Fool '-Wall'.  */
 }
 
 static void
diff --git a/src/side.c b/src/side.c
index 19958b4..076b898 100644
--- a/src/side.c
+++ b/src/side.c
@@ -292,7 +292,7 @@ print_sdiff_hunk (struct change *hunk)
       fprintf (outfile, "c%ld,%ld\n", len0, len1);
     }
 
-  /* Print ``xxx  |  xxx '' lines */
+  /* Print "xxx  |  xxx " lines.  */
   if (changes == CHANGED)
     {
       for (i = first0, j = first1;  i <= last0 && j <= last1;  i++, j++)
@@ -302,7 +302,7 @@ print_sdiff_hunk (struct change *hunk)
       next1 = first1 = j;
     }
 
-  /* Print ``     >  xxx '' lines */
+  /* Print "     >  xxx " lines.  */
   if (changes & NEW)
     {
       for (j = first1; j <= last1; ++j)
@@ -310,7 +310,7 @@ print_sdiff_hunk (struct change *hunk)
       next1 = j;
     }
 
-  /* Print ``xxx  <     '' lines */
+  /* Print "xxx  <     " lines.  */
   if (changes & OLD)
     {
       for (i = first0; i <= last0; ++i)
diff --git a/src/system.h b/src/system.h
index 9919d68..2767b57 100644
--- a/src/system.h
+++ b/src/system.h
@@ -20,14 +20,14 @@
 
 #include <config.h>
 
-/* Use this to suppress gcc's `...may be used before initialized' warnings. */
+/* Use this to suppress gcc's "...may be used before initialized" warnings. */
 #ifdef lint
 # define IF_LINT(Code) Code
 #else
 # define IF_LINT(Code) /* empty */
 #endif
 
-/* Define `__attribute__' and `volatile' first
+/* Define '__attribute__' and 'volatile' first
    so that they're used consistently in all system includes.  */
 #if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 6) || __STRICT_ANSI__
 # define __attribute__(x)
@@ -99,7 +99,7 @@ int strcasecmp (char const *, char const *);
    - It's typically faster.
    POSIX 1003.1-2001 says that only '0' through '9' are digits.
    Prefer ISDIGIT to isdigit unless it's important to use the locale's
-   definition of `digit' even when the host does not conform to POSIX.  */
+   definition of 'digit' even when the host does not conform to POSIX.  */
 #define ISDIGIT(c) ((unsigned int) (c) - '0' <= 9)
 
 #include <errno.h>
diff --git a/src/util.c b/src/util.c
index 16638a3..2b0bbbf 100644
--- a/src/util.c
+++ b/src/util.c
@@ -27,7 +27,7 @@
 char const pr_program[] = PR_PROGRAM;
 
 /* Queue up one-line messages to be printed at the end,
-   when -l is specified.  Each message is recorded with a `struct msg'.  */
+   when -l is specified.  Each message is recorded with a 'struct msg'.  */
 
 struct msg
 {
@@ -121,7 +121,7 @@ message5 (char const *format_msgid, char const *arg1, char const *arg2,
     }
 }
 
-/* Output all the messages that were saved up by calls to `message'.  */
+/* Output all the messages that were saved up by calls to 'message'.  */
 
 void
 print_message_queue (void)
@@ -146,8 +146,8 @@ print_message_queue (void)
    to set up OUTFILE, the stdio stream for the output to go to.
 
    Usually, OUTFILE is just stdout.  But when -l was specified
-   we fork off a `pr' and make OUTFILE a pipe to it.
-   `pr' then outputs to our stdout.  */
+   we fork off a 'pr' and make OUTFILE a pipe to it.
+   'pr' then outputs to our stdout.  */
 
 static char const *current_name0;
 static char const *current_name1;
@@ -190,7 +190,7 @@ begin_output (void)
       if (fflush (stdout) != 0)
 	pfatal_with_name (_("write failed"));
 
-      /* Make OUTFILE a pipe to a subsidiary `pr'.  */
+      /* Make OUTFILE a pipe to a subsidiary 'pr'.  */
       {
 #if HAVE_WORKING_FORK
 	int pipes[2];
@@ -241,7 +241,7 @@ begin_output (void)
   else
     {
 
-      /* If -l was not specified, output the diff straight to `stdout'.  */
+      /* If -l was not specified, output the diff straight to 'stdout'.  */
 
       outfile = stdout;
 
@@ -270,7 +270,7 @@ begin_output (void)
 }
 
 /* Call after the end of output of diffs for one file.
-   Close OUTFILE and get rid of the `pr' subfork.  */
+   Close OUTFILE and get rid of the 'pr' subfork.  */
 
 void
 finish_output (void)
@@ -298,12 +298,12 @@ finish_output (void)
       if (status)
 	error (EXIT_TROUBLE, werrno,
 	       _(status == 126
-		 ? "subsidiary program `%s' could not be invoked"
+		 ? "subsidiary program '%s' could not be invoked"
 		 : status == 127
-		 ? "subsidiary program `%s' not found"
+		 ? "subsidiary program '%s' not found"
 		 : status == INT_MAX
-		 ? "subsidiary program `%s' failed"
-		 : "subsidiary program `%s' failed (exit status %d)"),
+		 ? "subsidiary program '%s' failed"
+		 : "subsidiary program '%s' failed (exit status %d)"),
 	       pr_program, status);
     }
 
@@ -677,7 +677,7 @@ print_number_range (char sepchar, struct file_data *file, lin a, lin b)
 
 /* Look at a hunk of edit script and report the range of lines in each file
    that it applies to.  HUNK is the start of the hunk, which is a chain
-   of `struct change'.  The first and last line numbers of file 0 are stored in
+   of 'struct change'.  The first and last line numbers of file 0 are stored in
    *FIRST0 and *LAST0, and likewise for file 1 in *FIRST1 and *LAST1.
    Note that these are internal line numbers that count from 0.