1 files changed, 34 insertions, 17 deletions

diff --git a/src/eval.c b/src/eval.c
index c05c8d8f8de..22b02b49521 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -856,11 +856,9 @@ usage: (let* VARLIST BODY...)  */)
 
   lexenv = Vinternal_interpreter_environment;
 
-  varlist = XCAR (args);
-  CHECK_LIST (varlist);
-  while (CONSP (varlist))
+  for (varlist = XCAR (args); CONSP (varlist); varlist = XCDR (varlist))
     {
-      QUIT;
+      maybe_quit ();
 
       elt = XCAR (varlist);
       if (SYMBOLP (elt))
@@ -894,9 +892,8 @@ usage: (let* VARLIST BODY...)  */)
         }
       else
         specbind (var, val);
-
-      varlist = XCDR (varlist);
     }
+  CHECK_LIST_END (varlist, XCAR (args));
 
   val = Fprogn (XCDR (args));
   return unbind_to (count, val);
@@ -928,7 +925,7 @@ usage: (let VARLIST BODY...)  */)
 
   for (argnum = 0; CONSP (varlist); varlist = XCDR (varlist))
     {
-      QUIT;
+      maybe_quit ();
       elt = XCAR (varlist);
       if (SYMBOLP (elt))
         temps [argnum++] = Qnil;
@@ -981,7 +978,7 @@ usage: (while TEST BODY...)  */)
   body = XCDR (args);
   while (!NILP (eval_sub (test)))
     {
-      QUIT;
+      maybe_quit ();
       prog_ignore (body);
     }
 
@@ -1014,7 +1011,7 @@ definitions to shadow the loaded ones for use in file byte-compilation.  */)
          until we get a symbol that is not an alias.  */
       while (SYMBOLP (def))
         {
-          QUIT;
+          maybe_quit ();
           sym = def;
           tem = Fassq (sym, environment);
           if (NILP (tem))
@@ -1134,7 +1131,6 @@ unwind_to_catch (struct handler *catch, Lisp_Object value)
   /* Restore certain special C variables.  */
   set_poll_suppress_count (catch->poll_suppress_count);
   unblock_input_to (catch->interrupt_input_blocked);
-  immediate_quit = 0;
 
   do
     {
@@ -1453,7 +1449,7 @@ static Lisp_Object find_handler_clause (Lisp_Object, Lisp_Object);
 static bool maybe_call_debugger (Lisp_Object conditions, Lisp_Object sig,
                                  Lisp_Object data);
 
-void
+static void
 process_quit_flag (void)
 {
   Lisp_Object flag = Vquit_flag;
@@ -1465,6 +1461,28 @@ process_quit_flag (void)
   quit ();
 }
 
+/* Check quit-flag and quit if it is non-nil.  Typing C-g does not
+   directly cause a quit; it only sets Vquit_flag.  So the program
+   needs to call maybe_quit at times when it is safe to quit.  Every
+   loop that might run for a long time or might not exit ought to call
+   maybe_quit at least once, at a safe place.  Unless that is
+   impossible, of course.  But it is very desirable to avoid creating
+   loops where maybe_quit is impossible.
+
+   If quit-flag is set to `kill-emacs' the SIGINT handler has received
+   a request to exit Emacs when it is safe to do.
+
+   When not quitting, process any pending signals.  */
+
+void
+maybe_quit (void)
+{
+  if (!NILP (Vquit_flag) && NILP (Vinhibit_quit))
+    process_quit_flag ();
+  else if (pending_signals)
+    process_pending_signals ();
+}
+
 DEFUN ("signal", Fsignal, Ssignal, 2, 2, 0,
        doc: /* Signal an error.  Args are ERROR-SYMBOL and associated DATA.
 This function does not return.
@@ -1508,10 +1526,9 @@ signal_or_quit (Lisp_Object error_symbol, Lisp_Object data, bool keyboard_quit)
   Lisp_Object string;
   Lisp_Object real_error_symbol
     = (NILP (error_symbol) ? Fcar (data) : error_symbol);
-  register Lisp_Object clause = Qnil;
+  Lisp_Object clause = Qnil;
   struct handler *h;
 
-  immediate_quit = 0;
   if (gc_in_progress || waiting_for_input)
     emacs_abort ();
 
@@ -2129,7 +2146,7 @@ eval_sub (Lisp_Object form)
   if (!CONSP (form))
     return form;
 
-  QUIT;
+  maybe_quit ();
 
   maybe_gc ();
 
@@ -2715,7 +2732,7 @@ usage: (funcall FUNCTION &rest ARGUMENTS)  */)
   Lisp_Object val;
   ptrdiff_t count;
 
-  QUIT;
+  maybe_quit ();
 
   if (++lisp_eval_depth > max_lisp_eval_depth)
     {
@@ -2960,7 +2977,7 @@ funcall_lambda (Lisp_Object fun, ptrdiff_t nargs,
   bool previous_optional_or_rest = false;
   for (; CONSP (syms_left); syms_left = XCDR (syms_left))
     {
-      QUIT;
+      maybe_quit ();
 
       next = XCAR (syms_left);
       if (!SYMBOLP (next))
@@ -3098,7 +3115,7 @@ lambda_arity (Lisp_Object fun)
       if (EQ (XCAR (fun), Qclosure))
         {
           fun = XCDR (fun);     /* Drop `closure'.  */
-          CHECK_LIST_CONS (fun, fun);
+          CHECK_CONS (fun);
         }
       syms_left = XCDR (fun);
       if (CONSP (syms_left))