Revert the commit below. A better solution is being discussed on newlib's mailing list.

commit fcd33916ac03086b9090c68e88036afa4b25d913
Author: Alexander Fedotov <alfedotov@gmail.com>
Date:   Mon Dec 25 16:28:22 2017 +0300

    fix incompatible pointer type for va_list in nano versions of printf and scanf for target like PowerPC

diff --git b/newlib/libc/stdio/nano-vfprintf.c a/newlib/libc/stdio/nano-vfprintf.c
index 663eb7149..e6604e771 100644
--- b/newlib/libc/stdio/nano-vfprintf.c
+++ a/newlib/libc/stdio/nano-vfprintf.c
@@ -168,16 +168,6 @@ static char *rcsid = "$Id$";
 #include "vfieeefp.h"
 #include "nano-vfprintf_local.h"
 
-
-/* GCC PR 14577 at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=14557 */
-#if __STDC_VERSION__ >= 201112L
-#define va_ptr(ap) _Generic(&(ap), va_list *: &(ap), default: (va_list *)(ap))
-#elif __GNUC__ >= 4
-#define va_ptr(ap) __builtin_choose_expr(__builtin_types_compatible_p(__typeof__(&(ap)), va_list *), &(ap), (va_list *)(ap))
-#else
-#define va_ptr(ap) (sizeof(ap) == sizeof(va_list) ? (va_list *)&(ap) : (va_list *)(ap))
-#endif
-
 /* The __ssputs_r function is shared between all versions of vfprintf
    and vfwprintf.  */
 #ifdef STRING_ONLY
@@ -643,12 +633,12 @@ _DEFUN(_VFPRINTF_R, (data, fp, fmt0, ap),
 	    }
 	  else
 	    {
-	      n = _printf_float (data, &prt_data, fp, pfunc, va_ptr(ap));
+	      n = _printf_float (data, &prt_data, fp, pfunc, &ap);
 	    }
 	}
       else
 #endif
-	n = _printf_i (data, &prt_data, fp, pfunc, va_ptr(ap));
+	n = _printf_i (data, &prt_data, fp, pfunc, &ap);
 
       if (n == -1)
 	goto error;
diff --git b/newlib/libc/stdio/nano-vfscanf.c a/newlib/libc/stdio/nano-vfscanf.c
index 6467e5425..564f2916d 100644
--- b/newlib/libc/stdio/nano-vfscanf.c
+++ a/newlib/libc/stdio/nano-vfscanf.c
@@ -119,15 +119,6 @@ Supporting OS subroutines required:
 #include "../stdlib/local.h"
 #include "nano-vfscanf_local.h"
 
-/* GCC PR 14577 at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=14557 */
-#if __STDC_VERSION__ >= 201112L
-#define va_ptr(ap) _Generic(&(ap), va_list *: &(ap), default: (va_list *)(ap))
-#elif __GNUC__ >= 4
-#define va_ptr(ap) __builtin_choose_expr(__builtin_types_compatible_p(__typeof__(&(ap)), va_list *), &(ap), (va_list *)(ap))
-#else
-#define va_ptr(ap) (sizeof(ap) == sizeof(va_list) ? (va_list *)&(ap) : (va_list *)(ap))
-#endif
-
 #define VFSCANF vfscanf
 #define _VFSCANF_R _vfscanf_r
 #define __SVFSCANF __svfscanf
@@ -433,12 +424,12 @@ _DEFUN(__SVFSCANF_R, (rptr, fp, fmt0, ap),
 	}
       ret = 0;
       if (scan_data.code < CT_INT)
-	ret = _scanf_chars (rptr, &scan_data, fp, va_ptr(ap));
+	ret = _scanf_chars (rptr, &scan_data, fp, &ap);
       else if (scan_data.code < CT_FLOAT)
-	ret = _scanf_i (rptr, &scan_data, fp, va_ptr(ap));
+	ret = _scanf_i (rptr, &scan_data, fp, &ap);
 #ifdef FLOATING_POINT
       else if (_scanf_float)
-	ret = _scanf_float (rptr, &scan_data, fp, va_ptr(ap));
+	ret = _scanf_float (rptr, &scan_data, fp, &ap);
 #endif
 
       if (ret == MATCH_FAILURE)