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* [Bug c++/55148] New: wrong compilation of chars: overlapped memory areas @ 2012-10-31 12:10 icegood1980 at gmail dot com 2012-10-31 12:17 ` [Bug c++/55148] " redi at gcc dot gnu.org ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: icegood1980 at gmail dot com @ 2012-10-31 12:10 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55148 Bug #: 55148 Summary: wrong compilation of chars: overlapped memory areas Classification: Unclassified Product: gcc Version: 4.7.2 Status: UNCONFIRMED Severity: major Priority: P3 Component: c++ AssignedTo: unassigned@gcc.gnu.org ReportedBy: icegood1980@gmail.com if one uses a stringification operation then problems could be obtained on stack: brackets.cpp : #include <iostream> #include <cstring> #define GLOBAL_str_intermediate(s) \ ({ \ char GLOBAL_str_intermediate_buf[1024]; \ strcpy(GLOBAL_str_intermediate_buf, #s); \ GLOBAL_str_intermediate_buf[strlen(GLOBAL_str_intermediate_buf)-1]='\0'; \ GLOBAL_str_intermediate_buf+1; \ }) #define GLOBAL_str(s) GLOBAL_str_intermediate((s)) #define s_one_arg a,b,c int main(int argc, const char **argv) { char PairPotentialName[70], *p=GLOBAL_str(s_one_arg); // std::cerr<<p-PairPotentialName<<std::endl; std::cerr<<PairPotentialName+1<<std::endl; return 0; } g++ brackets.cpp ./a.out: 1 a,b,c so PairPotentialName and p are overlapped! ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/55148] wrong compilation of chars: overlapped memory areas 2012-10-31 12:10 [Bug c++/55148] New: wrong compilation of chars: overlapped memory areas icegood1980 at gmail dot com @ 2012-10-31 12:17 ` redi at gcc dot gnu.org 2012-10-31 12:23 ` redi at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: redi at gcc dot gnu.org @ 2012-10-31 12:17 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55148 Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|major |normal --- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-10-31 12:16:51 UTC --- As the docs for the Statement Expressions extension (http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html) say: "Any temporaries created within a statement within a statement expression will be destroyed at the statement's end." so GLOBAL_str_intermediate_buf[] is no longer valid after p is initialized and the memory can be reused. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/55148] wrong compilation of chars: overlapped memory areas 2012-10-31 12:10 [Bug c++/55148] New: wrong compilation of chars: overlapped memory areas icegood1980 at gmail dot com 2012-10-31 12:17 ` [Bug c++/55148] " redi at gcc dot gnu.org @ 2012-10-31 12:23 ` redi at gcc dot gnu.org 2012-10-31 12:40 ` icegood1980 at gmail dot com 2012-10-31 12:43 ` icegood1980 at gmail dot com 3 siblings, 0 replies; 5+ messages in thread From: redi at gcc dot gnu.org @ 2012-10-31 12:23 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55148 --- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-10-31 12:22:54 UTC --- http://gcc.gnu.org/gcc-4.7/changes.html#cxx notes "G++ now properly re-uses stack space allocated for temporary objects when their lifetime ends, which can significantly lower stack consumption for some C++ functions. As a result of this, some code with undefined behavior will now break" ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/55148] wrong compilation of chars: overlapped memory areas 2012-10-31 12:10 [Bug c++/55148] New: wrong compilation of chars: overlapped memory areas icegood1980 at gmail dot com 2012-10-31 12:17 ` [Bug c++/55148] " redi at gcc dot gnu.org 2012-10-31 12:23 ` redi at gcc dot gnu.org @ 2012-10-31 12:40 ` icegood1980 at gmail dot com 2012-10-31 12:43 ` icegood1980 at gmail dot com 3 siblings, 0 replies; 5+ messages in thread From: icegood1980 at gmail dot com @ 2012-10-31 12:40 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55148 icegood1980@gmail.com <icegood1980 at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|normal |major --- Comment #3 from icegood1980 at gmail dot com <icegood1980 at gmail dot com> 2012-10-31 12:40:16 UTC --- Clear! it's my fault. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/55148] wrong compilation of chars: overlapped memory areas 2012-10-31 12:10 [Bug c++/55148] New: wrong compilation of chars: overlapped memory areas icegood1980 at gmail dot com ` (2 preceding siblings ...) 2012-10-31 12:40 ` icegood1980 at gmail dot com @ 2012-10-31 12:43 ` icegood1980 at gmail dot com 3 siblings, 0 replies; 5+ messages in thread From: icegood1980 at gmail dot com @ 2012-10-31 12:43 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55148 icegood1980@gmail.com <icegood1980 at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution| |INVALID --- Comment #4 from icegood1980 at gmail dot com <icegood1980 at gmail dot com> 2012-10-31 12:43:32 UTC --- my fault ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2012-10-31 12:43 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2012-10-31 12:10 [Bug c++/55148] New: wrong compilation of chars: overlapped memory areas icegood1980 at gmail dot com 2012-10-31 12:17 ` [Bug c++/55148] " redi at gcc dot gnu.org 2012-10-31 12:23 ` redi at gcc dot gnu.org 2012-10-31 12:40 ` icegood1980 at gmail dot com 2012-10-31 12:43 ` icegood1980 at gmail dot com
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