Low-level diagnostics now use ‘text-quoting-style’

* src/doprnt.c (doprnt):
Format ` and ' as per ‘text-quoting-style’.
* src/xdisp.c (vmessage, message): Mention that the format should
not contain ` or '.

2 files changed, 42 insertions, 24 deletions

diff --git a/src/doprnt.c b/src/doprnt.c
index 68750f519e6..7c5a6afb94b 100644
--- a/src/doprnt.c
+++ b/src/doprnt.c
@@ -49,8 +49,9 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
    support features beyond those in `Fformat', which is used by `error' on the
    Lisp level.  */
 
-/* This function supports the following %-sequences in the `format'
-   argument:
+/* In the FORMAT argument this function supports ` and ' as directives
+   that output left and right quotes as per ‘text-quoting style’.  It
+   also supports the following %-sequences:
 
    %s means print a string argument.
    %S is silently treated as %s, for loose compatibility with `Fformat'.
@@ -144,6 +145,7 @@ doprnt (char *buffer, ptrdiff_t bufsize, const char *format,
   /* Buffer we have got with malloc.  */
   char *big_buffer = NULL;
 
+  enum text_quoting_style quoting_style = text_quoting_style ();
   ptrdiff_t tem = -1;
   char *string;
   char fixed_buffer[20];        /* Default buffer for small formatting. */
@@ -164,7 +166,9 @@ doprnt (char *buffer, ptrdiff_t bufsize, const char *format,
   /* Loop until end of format string or buffer full. */
   while (fmt < format_end && bufsize > 0)
     {
-      if (*fmt == '%')  /* Check for a '%' character */
+      char const *fmt0 = fmt;
+      char fmtchar = *fmt++;
+      if (fmtchar == '%')
         {
           ptrdiff_t size_bound = 0;
           ptrdiff_t width;  /* Columns occupied by STRING on display.  */
@@ -180,7 +184,6 @@ doprnt (char *buffer, ptrdiff_t bufsize, const char *format,
           int maxmlen = max (max (1, pDlen), max (pIlen, pMlen));
           int mlen;
 
-          fmt++;
           /* Copy this one %-spec into fmtcpy.  */
           string = fmtcpy;
           *string++ = '%';
@@ -438,22 +441,36 @@ doprnt (char *buffer, ptrdiff_t bufsize, const char *format,
             }
         }
 
-      {
-        /* Just some character; Copy it if the whole multi-byte form
-           fit in the buffer.  */
-        char *save_bufptr = bufptr;
-
-        do { *bufptr++ = *fmt++; }
-        while (fmt < format_end && --bufsize > 0 && !CHAR_HEAD_P (*fmt));
-        if (!CHAR_HEAD_P (*fmt))
-          {
-            /* Truncate, but return value that will signal to caller
-               that the buffer was too small.  */
-            *save_bufptr = 0;
-            break;
-          }
-      }
-    };
+      char const *src;
+      ptrdiff_t srclen;
+      if (quoting_style == CURVE_QUOTING_STYLE && fmtchar == '`')
+        src = uLSQM, srclen = sizeof uLSQM - 1;
+      else if (quoting_style == CURVE_QUOTING_STYLE && fmtchar == '\'')
+        src = uRSQM, srclen = sizeof uRSQM - 1;
+      else if (quoting_style == STRAIGHT_QUOTING_STYLE && fmtchar == '`')
+        src = "'", srclen = 1;
+      else
+        {
+          while (fmt < format_end && !CHAR_HEAD_P (*fmt))
+            fmt++;
+          src = fmt0, srclen = fmt - fmt0;
+        }
+
+      if (bufsize < srclen)
+        {
+          /* Truncate, but return value that will signal to caller
+             that the buffer was too small.  */
+          do
+            *bufptr++ = '\0';
+          while (--bufsize != 0);
+        }
+      else
+        {
+          do
+            *bufptr++ = *src++;
+          while (--srclen != 0);
+        }
+    }
 
   /* If we had to malloc something, free it.  */
   xfree (big_buffer);
@@ -467,7 +484,8 @@ doprnt (char *buffer, ptrdiff_t bufsize, const char *format,
 /* Format to an unbounded buffer BUF.  This is like sprintf, except it
    is not limited to returning an 'int' so it doesn't have a silly 2
    GiB limit on typical 64-bit hosts.  However, it is limited to the
-   Emacs-style formats that doprnt supports.
+   Emacs-style formats that doprnt supports, and it requotes ` and '
+   as per ‘text-quoting-style’.
 
    Return the number of bytes put into BUF, excluding the terminating
    '\0'.  */
diff --git a/src/xdisp.c b/src/xdisp.c
index 52c77bd434d..6d747ebc5ce 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -10275,9 +10275,9 @@ message_with_string (const char *m, Lisp_Object string, bool log)
 /* Dump an informative message to the minibuf.  If M is 0, clear out
    any existing message, and let the mini-buffer text show through.
 
-   The message must be safe ASCII only.  If strings may contain escape
-   sequences or non-ASCII characters, convert them to Lisp strings and
-   use Fmessage.  */
+   The message must be safe ASCII and the format must not contain ` or
+   '.  If your message and format do not fit into this category,
+   convert your arguments to Lisp objects and use Fmessage instead.  */
 
 static void ATTRIBUTE_FORMAT_PRINTF (1, 0)
 vmessage (const char *m, va_list ap)