[Issue 8725] segmentation fault with negative-lookahead in module-level regex
http://d.puremagic.com/issues/show_bug.cgi?id=8725 --- Comment #5 from github-bugzi...@puremagic.com 2012-12-01 00:12:43 PST --- Commit pushed to master at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/0f2947d4d1360f0a0f797279e6f13f95695e45ec bugfixes for compile-time regex fix issue 8725 fix issue 8349 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 8725] segmentation fault with negative-lookahead in module-level regex
http://d.puremagic.com/issues/show_bug.cgi?id=8725 Dmitry Olshansky dmitry.o...@gmail.com changed: What|Removed |Added Status|NEW |RESOLVED Resolution||DUPLICATE --- Comment #4 from Dmitry Olshansky dmitry.o...@gmail.com 2012-11-30 12:49:42 PST --- Works with current git master. Must have been fixed along with the compiler bug in 7810. *** This issue has been marked as a duplicate of issue 7810 *** -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 8725] segmentation fault with negative-lookahead in module-level regex
http://d.puremagic.com/issues/show_bug.cgi?id=8725
Dmitry Olshansky dmitry.o...@gmail.com changed:
What|Removed |Added
CC||dmitry.o...@gmail.com
--- Comment #2 from Dmitry Olshansky dmitry.o...@gmail.com 2012-09-26
06:46:49 PDT ---
I suspect that is a long standing bug with compile-time evaluation that
compiler parses regex pattern at compile time wrongly (unlike at R-T).
See also: http://d.puremagic.com/issues/show_bug.cgi?id=7810
The problem is that once D compiler sees an initialized global variable it has
to const-fold it:
int fact10 = factorial(10);
//will compute and hardcode the value of factorial(10)
then with regex ...:
auto italic = regex( ... );
// *parses* and *generates* binary object for compiled regex pattern object
with all the datastructures for matching it
All of this *at compile time* via CTFE, see about it here (near the bottom of):
http://dlang.org/function.html
Though previously it only caused unexpectedly long compilation time (CTFE is
slow) and in a select cases it failed with assert *during compilation*, it
never segfaulted.
Probably internal structure has subtle corruption that self-test failed to
catch.
E.g this one also works because italic regex is created at run-time:
import std.stdio;
import std.regex;
void main() {
auto italic = regex( r\*
(?!\s+)
(.*?)
(?!\s+)
\*, gx );
string input = this * is* interesting, *very* interesting;
writeln( replace( input, italic, i$1/i ) );
}
Also a tip: the second lookahead should be lookbehind! As is is it will test
that \* is not a space indeed... Also both can be just \s, because \s+ matches
whenever \s matches. And since you don't capture the contents of
lookahead/lookbehind it'll be faster/simpler to use a single \s.
About SafeD: it shouldn't segfault but the program listed is @system (as this
is the default) :). Otherwise since regex is @trusted, it's my responsibilty to
verfiy that it is memory safe, so blame me (or rather the compiler).
To be actually in SafeD try putting @safe: at the top of your code or just tag
main and all functions with @safe.
AFAIK writeln in SafeD wouldn't work as it's still @system (obviously it
should be safe/trusted). To be honest SafeD hasn't been addressed properly in
the standard library yet.
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[Issue 8725] segmentation fault with negative-lookahead in module-level regex
http://d.puremagic.com/issues/show_bug.cgi?id=8725 --- Comment #3 from Val Markovic v...@markovic.io 2012-09-26 09:39:30 PDT --- Thanks for the explanation! WRT the regex string being faulty, I was aware of that; I was just experimenting when I encountered a segfault. Thanks for the pointer about adding @safe: at the top; too bad writeln is still @system. That kinda kills the usefulness of SafeD, doesn't it? I mean if I literally can't write a Hello World program in SafeD, then SafeD is quite far from ready. :) I've read the TDPL last week and this is my first encounter with writing real D code; all in all, the language is freaking awesome (goodbye C++) and I'm even willing to live with esoteric bugs in the compiler/libs if I can work around them. I understand that D is still a work-in-progress language. I intend to write a substantial (multi KLOC) D program as a learning experience; will report any bugs I find as I find them. Anyway, good luck fixing this. :) -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 8725] segmentation fault with negative-lookahead in module-level regex
http://d.puremagic.com/issues/show_bug.cgi?id=8725 --- Comment #1 from Val Markovic v...@markovic.io 2012-09-25 22:33:03 PDT --- Oh, and the segfault goes away if I put the regex creation directly in the call, like so: writeln( replace( input, regex( r\* (?!\s+) (.*?) (?!\s+) \*, gx ), i$1/i ) ); -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
