bug#20782: 25.0.50; Emacs crashes when creating a file with emacs-template package w/o interactive call

[Eli Zaretskii]

> From: vincent.belaiche@gmail.com (Vincent Belaïche)
> Cc: Vincent Belaïche <vincent.belaiche@gmail.com> ,
>  20782@debbugs.gnu.org
> Date: Wed, 10 Jun 2015 23:51:27 +0200
> 
> Program received signal SIGSEGV, Segmentation fault.
> SYMBOL_NAME (sym=2) at lisp.h:1662
> 1662    return XSYMBOL (sym)->name;
> (gdb) bt full
> #0  SYMBOL_NAME (sym=2) at lisp.h:1662
> No locals.
> #1  print_object (obj=2, printcharfun=printcharfun@entry=21101962, 
>     escapeflag=escapeflag@entry=true) at print.c:1539
>         end = <optimized out>
>         c = <optimized out>
>         i_byte = <optimized out>
>         confusing = <optimized out>
>         p = <optimized out>
>         buf = "\377\377\377\377\000\000\000\000\000\000\366\000*\271\272w 
> \343i\t\240\345\210\000\270\032\305w8\001\366\000\234\032\305wpi\261o"
> #2  0x0111d13c in print (obj=obj@entry=2, 
>     printcharfun=printcharfun@entry=21101962, 
>     escapeflag=escapeflag@entry=true) at print.c:1139
> No locals.
> #3  0x0111d27e in Fprin1 (object=2, printcharfun=21101962) at print.c:581
>         old = 0x95ce900
>         old_point = <optimized out>
>         start_point = <optimized out>
>         old_point_byte = <optimized out>
>         start_point_byte = <optimized out>
>         free_print_buffer = true
>         multibyte = true
>         original = <optimized out>

This shows that Emacs crashed in 'prin1' trying to format an invalid
Lisp symbol for display in a backtrace.  'prin1' was called by the
debugger, so I think Emacs was in the process of reporting a Lisp
error by invoking the debugger.  Any idea what Lisp error could that
be?

Can you "M-x load-file RET template.el RET" before repeating the
recipe, so that the Lisp-level backtrace shows more detailed
information?