cookie.c triggers C1001 under msvc 14 with -O2

[plujon]

lib/cookie.c and lib/strcase.c team up to trigger an internal compiler error under msvc-14.

Here's a reduced translation unit that triggers the bug.

#include <stddef.h>

#define COOKIE_HASH_SIZE 256

char Curl_raw_toupper(char in);

size_t cookie_hash_domain(const char *domain, const size_t len)
{
  const char *end = domain + len;
  size_t h = 5381;

  while(domain < end) {
    h += h << 5;
    h ^= Curl_raw_toupper(*domain++);
  }

  return (h % COOKIE_HASH_SIZE);
}

/*
 * cl -O2 -c t.c
 *
 * t.c(..) : fatal error C1001: An internal error has occurred in the compiler.
 * (compiler file 'f:/dd/vctools/compiler/utc/src/p2/main.c', line 246)
 *  To work around this problem, try simplifying or changing the program near the locations listed above.
 * Please choose the Technical Support command on the Visual C++
 *  Help menu, or open the Technical Support help file for more information
 *
 * INTERNAL COMPILER ERROR in 'C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/BIN/cl.exe'
 *     Please choose the Technical Support command on the Visual C++
 *     Help menu, or open the Technical Support help file for more information
 */

I have verified the bug is hit when _MSC_VER is 1900, but not when _MSC_VER is 1926 (msvc-15).

Disabling optimization for msvc-14 avoids the problem.

#if _MSC_VER == 1900
#pragma optimize("", off)
#endif

size_t cookie_hash_domain(const char *domain, const size_t len)
. . .

#if _MSC_VER == 1900
#pragma optimize("", on)
#endif

[bagder]

This is a compiler bug, not a curl bug!

It makes me curious. This function you point out to trigger this problem has been around for a long time and lots of users have compiled curl in the mean time. Did really none of them use this optimization level with this compiler version?

Can you submit the proposed work-around as a pull request?

[jay]

How are you building curl that this happens? I don't recall anyone else reporting this.

[plujon]

cd winbuild && nmake /f Makefile.vc mode=dll GEN_PDB=yes