Given:
#include <algorithm>
class Id {
public:
Id();
Id( const Id & );
operator int() const;
int id;
};
int get_int();
int main()
{
struct SideVertexBuffer {
enum { max_vertices = 4 };
Id node_id[ max_vertices ] ;
int processor ;
};
SideVertexBuffer entry;
int num_side_vert = get_int();
std::sort(entry.node_id, entry.node_id+num_side_vert);
}
when compiled as:
g++ -finline-functions -O2 -Wall -c test.C
Gives the warning message:
/home/sntools/extras/compilers/gcc-4.3.1/lib/gcc/x86_64-unknown-linux-gnu/4.3.1/../../../../include/c++/4.3.1/bits/stl_algo.h:In
function âint main()â:
/home/sntools/extras/compilers/gcc-4.3.1/lib/gcc/x86_64-unknown-linux-gnu/4.3.1/../../../../include/c++/4.3.1/bits/stl_algo.h:1829:
warning: array subscript is above array bounds
We are required compile with -Werror, so this warning results in a build error
from our code.
As best I can tell, the error is due to _S_threshold being larger than the
dimensioned size of the array being passed to std::sort. Since the compiler is
inlining the functions, it "knows" that "__first+_S_threshold" is larger than
the dimensioned size of the array I pass to sort and emits the warning.
If I change the "num_side_vert" variable to an explicit value (num_side_vert =
4), then I don't get the warning since the compiler then knows that the one
branch of the if statement won't be taken in std::sort.
--
Summary: warning: array subscript is above array bounds.
Product: gcc
Version: 4.3.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: gdsjaar at sandia dot gov
GCC build triplet: x86_64-unknown-linux-gnu
GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37130
