I was searching the Web for system programming languages, found BitC
and decided to rsync it out. However, I encountered a few bugs and
investigated them a little. I couldn't find a bug tracker, so I
thought I'd post my findings here. For the record, I'm running the
AMD64 version of Ubuntu Linux.
1. This is the most obvious one: lib64/libbitc.bita is missing
whitespace after import statements, resulting in lines such as
"(importbitc.stdio as stdio)".
2. Reading a character from standard input often segfaults. The cause
is libbitc/stdio.c and a null/uninitialized pointer. Placing
assert(ios->f) right after fix_stdio_stream(ios) _sometimes_ catches a
null pointer. This is pretty strange, because
struct ty_bitc_stdioStream {
FILE *f;
} ;
static ty_bitc_stdioStream our_stdin = { 0 };
ty_bitc_stdioStream *bitc_stdio_stdin = &our_stdin;
static inline void
fix_stdio_stream(ty_bitc_stdioStream *ios)
{
if (ios->f == 0) {
if (ios == &our_stdin)
ios->f = stdin;
...
would appear to be correct. Debugging is quite difficult because
adding just one assertion may "correct" the behaviour. GDB blames the
line "result = fread(&encoded[0], 1, 1, ios->f)", as expected.
However, ios->f wasn't null at this time. After disabling garbage
collection, Valgrind seems to agree. (Otherwise it appears to segfault
on garbage collection.)
The bitc file I used looked like this:
(bitc-version "0.10")
(import bitc.main as main)
(provide bitc.main main)
(import bitc.stdio as stdio)
(define main.main:(fn (vector string) -> int32)
(lambda (argvec)
(stdio.read-char stdio.stdin)
(stdio.write-string stdio.stdout "hello")
(stdio.write-char stdio.stdout #\linefeed)
0))
3. This is not a bug per se, but rather an usability nitpick. I had to
read the source to find out how to make bitcc find its libraries from
a nonstandard --prefix location and to output C code.
Anyway, BitC is certainly an extremely interesting project, and I
might be able to contribute at least by sending bugfixes. Where would
you like bug reports and patches to be sent?
Aleksi Nurmi
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