c++ - C++98/C++03 STL set bug? -

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all,

one weird thing happens when i'm using set: let's say:

struct {   int num;   bool operator<(const a& x) const   {     return num < x.num;   } };  struct b {   set<a> aset; };  struct c {   list<b> blist;   list<b>::iterator blistiter;   c()   {     blist.push_back(b());     blistiter = --(blist.end());   } };

somewhere can have code:

list<c> clist; clist.push_back(c()); list<c>::iterator clistiter = --(clist.end()); (...) {   a = ...;   ...   clistiter->blistiter->aset.insert(a);

this end segmentation fault after few iterations. when happens, found invalid item referenced , compared (its address 0x0000001b, wrong) during insertion.

funny thing when turn on -std=c++0x option use c++11 problem goes aways! wonder if bug of stl set in c++98/c++03?

thanks,

kevin

in c++03 or earlier, copies of temporary objects put on clist , blist inside clist object.

when c::blist member copied, new list<b> created, when c::blistiter member copied, new c::blistiter iterator still refers c::blist list in original c object - temporary gets destroyed. iterator refers element of destroyed list.

in c++11 move constructors used instead of copy constructors, resulting iterator doesn't refer dead object.


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