[Bug c++/63728] Memory exhaustion using constexpr constructors for classes with large array members

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63728

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2016-05-13
                 CC|                            |msebor at gcc dot gnu.org
             Blocks|                            |55004
     Ever confirmed|0                           |1
      Known to fail|                            |4.9.3, 5.3.0, 6.1.0

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirmed.  Unbounded constexpr can eat up a lot of memory.  Here's a smaller
test case:

$ (cat xx.cpp && ulimit -v $(expr 4096 \* 16) && /build/gcc-trunk-svn/gcc/xg++
-B /build/gcc-trunk-svn/gcc -DNBITS=10000 -S -Wall -Wextra  xx.cpp); echo $?
template <int N>
struct S
{
    int a [N / (8 * sizeof (int))];
    constexpr S (): a () { }
};

S<NBITS> s;
0

$ (ulimit -v $(expr 4096 \* 16) && /build/gcc-trunk-svn/gcc/xg++ -B
/build/gcc-trunk-svn/gcc -DNBITS=10000000 -S -Wall -Wextra  xx.cpp); echo
$?virtual memory exhausted: Cannot allocate memory
1


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55004
[Bug 55004] [meta-bug] constexpr issues