Fix for bug #28240: "isinf()" cannot be used in C++ for lack of prototype

- Since isinf() portability across various platforms and
  compilers is a complicated question, we should not use
  it directly. Instead, the my_isinf() macro should be used,
  which is defined as an alias to the system-defined isinf()
  if it is safe to use, or a workaround implementation otherwise


configure.in:
  Added a check to define HAVE_ISINF only if it can be used
  in C++ code as well.
include/my_global.h:
  Define my_isinf() as an alias to isinf(), if it is available
  in both C and C++ code. Otherwise, define it to a workaround
  implementation.
sql/item_func.cc:
  Replaced isinf() with my_isinf().
strings/strtod.c:
  Replaced isinf() with my_isinf().

1 files changed, 1 insertions, 1 deletions

diff --git a/strings/strtod.c b/strings/strtod.c
index 15707a9b944..7196cafb2c9 100644
--- a/strings/strtod.c
+++ b/strings/strtod.c
@@ -194,7 +194,7 @@ double my_strtod(const char *str, char **end_ptr, int *error)
 done:
   *end_ptr= (char*) str;                        /* end of number */
 
-  if (overflow || isinf(result))
+  if (overflow || my_isinf(result))
   {
     result= DBL_MAX;
     *error= EOVERFLOW;