[Boost-users] boost::intrusive::slist push_back() => error: static assertion failed: (cache_last)

[Jonas Printzén]

Hi All!  First post...

Attempt switching to intrusive slist for efficiency, the following example is

simply cut-paste from docs. Won't compile!  g++ 4.9.1 complains as
inlined in code below.

#include <boost/intrusive/slist.hpp>
using namespace boost::intrusive;

struct point : slist_base_hook<> {
  int64_t x,y;
};

using points = slist<point>;

int main() {
  points plist;
  point p1,p2,p3;

  ACCEPT( 0U == plist.size() );

  plist.push_back( p1 );         // => error: static assertion failed: (cache_last)

  ACCEPT( 1U == plist.size() );
}

The code is from the docs of my version (1.55) and im pretty sure

this or similar worked before. (1.54 i think)

Please help, what am I missing?

[Ion Gaztañaga]

El 09/05/2015 a las 12:12, Jonas Printzén escribió:
> Hi All! First post...
>
> Attempt switching to intrusive slist for efficiency, the following
> example is
> simply cut-paste from docs. Won't compile! g++ 4.9.1 complains as
> inlined in code below.

Which docs? I can't see int64_t anywhere in the docs.

The issue is that you are using a singly linked list, which typically
only can push at front. Only if you use the "cache_last" option the
singly linked lists stores a pointer to the last element which allows
push_back. From push_back comments:

//! <b>Note</b>: Does not affect the validity of iterators and references.
//! This function is only available is cache_last<> is true.

Since cache_last option is not active the implementation static_asserts
as push_back can't be implemented.

Ion
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