bug#6991: Please keep bytecode out of *Backtrace* buffers

[Stefan Monnier]

>> > Why?  No reason given.  This is a reasonable request, which 
>> > would improve correspondence about bugs and user difficulties.
> And no response to that question.  I've reopened this bug.

You can try the simple patch below.  It doesn't cut it for me, and
I think the only way to make it work well would be to change the
representation of the byte-codes so that they're not just a "unibyte
string" but an object with a distinctive type: the patch only catches
the case where the byte-codes appear within a printed
byte-compiled-function, not when they're arguments to the `byte-code'
function or to the `make-byte-code' function, and I'm sure there can be
other cases.


        Stefan


=== modified file 'src/print.c'
--- src/print.c 2012-06-28 11:11:48 +0000
+++ src/print.c 2012-07-02 18:37:46 +0000
@@ -1937,8 +1937,11 @@
       else
        {
          ptrdiff_t size = ASIZE (obj);
+         int bytecode = 0;
+
          if (COMPILEDP (obj))
            {
              PRINTCHAR ('#');
+             bytecode = 1;
              size &= PSEUDOVECTOR_SIZE_MASK;
            }
@@ -1978,6 +1981,9 @@
              {
                if (i) PRINTCHAR (' ');
                tem = AREF (obj, i);
+               if (bytecode && i == 1 && INTEGERP (Vprint_level))
+                 strout ("\"..<bytecode>..\"", 16, 16, printcharfun);
+               else
                print_object (tem, printcharfun, escapeflag);
              }
            if (size < real_size)