"std::_debug_memset" is not declared

Question

I'm working on GCC119 from the compile farm. The machine is AIX 7.1, POWER8 with IBM XLC 13.1. I'm trying to use the debug heap:

gcc119$ cat test.cxx
#include <altivec.h>
#undef vector
#undef pixel
#undef bool

#include <cstdlib>

int main(int argc, char* argv[])
{
  unsigned char x[32];
  std::memset(x, 0x00, 32);

  return 0;
}

A compile results in:

gcc119$ xlC -DDEBUG -g3 -O0 -qheapdebug -qro test.cxx -o test.exe
"test.cxx", line 11.3: 1540-0130 (S) "std::_debug_memset" is not declared.

Both <cstring> and <string.h> result in the error. I also tried including <cstdlib> and <stdlib.h>, and they resulted in the same error.

The Optimization and Programming Guide manual has a good discussion of debugging memory functions, but the treatment is C only. It does not appear to treat C++.

How does one use debug heaps in a C++ program?

---

gcc119$ oslevel -s
7200-00-01-1543

gcc119$ xlC -qversion
IBM XL C/C++ for AIX, V13.1.3 (5725-C72, 5765-J07)
Version: 13.01.0003.0004

Answer 1

You should try including <string.h> instead and using unqualified memset. According to the IBM XL C/C++ Programming Guide, _debug_memset lives in string.h. So the question becomes, shouldn't <cstring> make it available via std::? In the IBM XL C/C++ Standard Library reference, it shows all of the using declarations, and the debug functions are not there.

namespace std
{
using ::size_t; using ::memcmp; using ::memcpy; using ::memmove;
using ::memset; using ::strcat; using ::strcmp; using ::strcoll;
using ::strcpy; using ::strcspn; using ::strerror; using ::strlen;
using ::strncat; using ::strncmp; using ::strncpy; using ::strspn;
using ::strtok; using ::strxfrm;
}

Answer 2

Based on @user10688376's observation here's what I've come up with. I think it is technically undefined behavior because I am not allowed to put symbols like _debug_memset and _debug_memcpy in the std namespace. At this point potential UB is better than a failed compile and no testing.

#if defined(_AIX) && (defined(__xlc__) || defined(__xlC__) || defined(__ibmxl__))
# if defined(__DEBUG_ALLOC__)
namespace std {
  using ::_debug_memset;
  using ::_debug_memcpy;
}
# endif
#endif

_AIX is used because it identifies the operating system. Debug heaps are not available on the Linux gear. (Some IBM XLC compilers run on Linux, too).

__xlc__ and __xlC__ are used to detect IBM XLC compiler 13.0 and earlier. This compiler is built completely by IBM.

__ibmxl__ is used to detect IBM XLC compiler 13.1 and later. This compiler uses a Clang front-end and IBM back-end. I think this is the "LLC" compiler referred to in LLVM Review 21078.

__DEBUG_ALLOC__ is used because the compiler sets it for -qheapdebug.