substitute-command-keys keeps quotes’ text props

Problem reported by Clément Pit--Claudel (Bug#23254).
* src/doc.c: Include intervals.h.
(Fsubstitute_command_keys): If the only substitutions are for
quotes, copy the source string’s text properties too, since no
substring lengths have changed.

1 files changed, 22 insertions, 3 deletions

diff --git a/src/doc.c b/src/doc.c
index 1d466612c66..7cdb0d03a81 100644
--- a/src/doc.c
+++ b/src/doc.c
@@ -34,6 +34,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "coding.h"
 #include "buffer.h"
 #include "disptab.h"
+#include "intervals.h"
 #include "keymap.h"
 
 /* Buffer used for reading from documentation file.  */
@@ -739,6 +740,7 @@ Otherwise, return a new string.  */)
 {
   char *buf;
   bool changed = false;
+  bool nonquotes_changed = false;
   unsigned char *strp;
   char *bufp;
   ptrdiff_t idx;
@@ -786,7 +788,7 @@ Otherwise, return a new string.  */)
         {
           /* \= quotes the next character;
              thus, to put in \[ without its special meaning, use \=\[.  */
-          changed = true;
+          changed = nonquotes_changed = true;
           strp += 2;
           if (multibyte)
             {
@@ -946,6 +948,8 @@ Otherwise, return a new string.  */)
           length = SCHARS (tem);
           length_byte = SBYTES (tem);
         subst:
+          nonquotes_changed = true;
+        subst_quote:
           changed = true;
           {
             ptrdiff_t offset = bufp - buf;
@@ -967,7 +971,7 @@ Otherwise, return a new string.  */)
           length = 1;
           length_byte = sizeof uLSQM - 1;
           idx = strp - SDATA (string) + 1;
-          goto subst;
+          goto subst_quote;
         }
       else if (strp[0] == '`' && quoting_style == STRAIGHT_QUOTING_STYLE)
         {
@@ -1003,7 +1007,22 @@ Otherwise, return a new string.  */)
     }
 
   if (changed)                  /* don't bother if nothing substituted */
-    tem = make_string_from_bytes (buf, nchars, bufp - buf);
+    {
+      tem = make_string_from_bytes (buf, nchars, bufp - buf);
+      if (!nonquotes_changed)
+        {
+          /* Nothing has changed other than quoting, so copy the string’s
+             text properties.  FIXME: Text properties should survive other
+             changes too.  */
+          INTERVAL interval_copy = copy_intervals (string_intervals (string),
+                                                   0, SCHARS (string));
+          if (interval_copy)
+            {
+              set_interval_object (interval_copy, tem);
+              set_string_intervals (tem, interval_copy);
+            }
+        }
+    }
   else
     tem = string;
   xfree (buf);