[Ecls-list] Issue: ECL fails to compile under Chinese Windows

[Daniel Kochmański]

Hey,

I'm very thankful for this detailed description. Really, well done! :-)
It is very helpful to know, where problem and what potential solution
is. I'm downloading now windows 7 trial version and will try to
reproduce error.

Best regards,
Daniel

Rujia Liu writes:

> Dear all,
>
> I'm a Chinese developer who have used ECL for some time in 2013. Although I don't use it recently, I'd like to report an old issue (and our investigations) that I struggled with.
>
> Problem: ECL fails to compile under CHINESE windows XP and windows 7, due to ecl_min.exe crash.
>
> This issue is present in 13.5 (and also 15.3.7-rc1) but not in version 12.12.1. 
>
> I've discussed this with Juan Jose in private emails (thanks, Juanjo!) but we were both quite busy and didn't finish it.
>
> However, we have some important observations: 
>
> 1. Before 2012-12-16, the whole ECL is working on our machines (not only ecl-min) so something that changed after that is causing this problem.
>
> 2. I debugged with windbg, found that ecl_min.exe crashed in cl_boot, here:
>
> if (cl_fboundp(@'ext::make-encoding') != ECL_NIL) {
>         maybe_fix_console_stream(cl_core.standard_input);
>         maybe_fix_console_stream(cl_core.standard_output);
>         maybe_fix_console_stream(cl_core.error_output);
>     }
>
> (BTW: our encoding is CP936 and windbg showed the code successfully detected this, i.e. known_cp[i].name is "WINDOWS-CP936")
>
> In maybe_fix_console_stream(cl_object stream), there is a call:
>
>     si_stream_external_format_set(stream, external_format);
>
> Then I traced into it, and found it got here:
>
> #ifdef ECL_CLOS_STREAMS
>         unlikely_if (ECL_INSTANCEP(stream)) {
>                 FEerror("Cannot change external format of stream ~A", 1, stream);  <--- *** it got here. ***
>         }
> #endif
>
> and here:
>
>                         cl_object elt_type = ecl_stream_element_type(stream);
>                         unlikely_if (elt_type != @'character' &&
>                                      elt_type != @'base-char')
>                                 FEerror("Cannot change external format"
>                                         "of binary stream ~A", 1, stream); <-- *** and here. ***
>                         set_stream_elt_type(stream, stream->stream.byte_size,
>                                             stream->stream.flags, format);
>
> Then in set_stream_elt_type, it got into an INFINITE RECURSION:
>
> static int
> parse_external_format(cl_object stream, cl_object format, int flags)
> {
>         if (format == @':default') {
>                 format = ecl_symbol_value(@'ext::*default-external-format*');
>         }
>     if (CONSP(format)) {  <-- this is always true, so it recurses indefinitely
>         flags = parse_external_format(stream, ECL_CONS_CDR(format), flags);
>         format = ECL_CONS_CAR(format);
>     }
>
> I don't know why format is such "infinite cons", maybe because of the FEerrors, the format variable is left in an abnormal state?
>
> 3. In ECL12.12.1, the condition below is not satisfied so the 'troublesome' maybe_fix_console_stream is not called at all (that's why ecl_min.exe does NOT crash under 12.12.1).
>
> if (cl_fboundp(@'ext::make-encoding') != ECL_NIL) {
>         maybe_fix_console_stream(cl_core.standard_input);
>         maybe_fix_console_stream(cl_core.standard_output);
>         maybe_fix_console_stream(cl_core.error_output);
>     }
>
> Actually, after I commented out these lines in git repository's master, everything seems to work fine.
>
> I've tested some programs, outputing chinese characters without any problem. But since I haven't tested a lot of program, I'm not sure whether there is any potential problem.
>
> Finally, my questions:
>
> 1. Is it possible to skip setting the external format? Actually our program will reset the encoding to utf-8, despite our windows defaults to CP936 so it really doesn't matter whether to set it in cl_boot. It's perfectly ok to set it to LATIN-1 instead. We tested ECL12.12.1, it depends on msvc/encodings directory (when I removed the director it asks for WINDOWS-CP936 file) but it works.
>
> 2. Since this issue affacts a lot of (potential) users, should we add it somewhere in the document or wrap these lines in a compiler directive so that user can choose to skip this part when compiling?
>
> BTW: I'm very happy to see that ECL has a new maintainer now. That's REALLY great!
> ‍
> Best regards,
> Rujia Liu------------------------------------------------------------------------------
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-- 
Daniel Kochmański | Poznań, Poland
;; aka jackdaniel

"Be the change that you wish to see in the world." - Mahatma Gandhi