Don't call modification hooks unprepared

Inhibit modification hooks when performing message coalescing because
in that case, we aren't doing the necessary preparation for running
modification hooks (i.e., we pass PREPARE=false for the insert_1_both
and del_range_both calls).  See also Bug#30823 and Bug#21824.
* src/xdisp.c (message_dolog): Let-bind inhibit-modification-hooks
to t around del_range_both calls.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 47286e25c80..93cd54a3240 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -10417,6 +10417,13 @@ message_dolog (const char *m, ptrdiff_t nbytes, bool nlflag, bool multibyte)
           ptrdiff_t this_bol, this_bol_byte, prev_bol, prev_bol_byte;
           printmax_t dups;
 
+          /* Since we call del_range_both passing false for PREPARE,
+             we aren't prepared to run modification hooks (we could
+             end up calling modification hooks from another buffer and
+             only with AFTER=t, Bug#21824).  */
+          ptrdiff_t count = SPECPDL_INDEX ();
+          specbind (Qinhibit_modification_hooks, Qt);
+
           insert_1_both ("\n", 1, 1, true, false, false);
 
           scan_newline (Z, Z_BYTE, BEG, BEG_BYTE, -2, false);
@@ -10462,6 +10469,8 @@ message_dolog (const char *m, ptrdiff_t nbytes, bool nlflag, bool multibyte)
                             -XFIXNAT (Vmessage_log_max) - 1, false);
               del_range_both (BEG, BEG_BYTE, PT, PT_BYTE, false);
             }
+
+          unbind_to (count, Qnil);
         }
       BEGV = marker_position (oldbegv);
       BEGV_BYTE = marker_byte_position (oldbegv);