Add <limits.h> integer width macros.

TS 18661-1 defines macros for the width of integer types, intended for
use with the fromfp functions to convert from floating-point types to
integer types of any width, in any rounding mode and with control over
whether "inexact" is raised.  Such macros are, of course, more
generally useful than just with those functions.

Those macros are added to <limits.h> and <stdint.h>.  This patch adds
the <limits.h> macros to glibc's header, with the <stdint.h> ones
intended to be added in a separate patch (which would add to the NEWS
entry created by this patch).  I've also added these macros to GCC's
headers for GCC 7, but definitions in glibc's <limits.h> are still
useful for older GCC, for non-GNU compilers and for when it's
_GNU_SOURCE rather than __STDC_WANT_IEC_60559_BFP_EXT__ that implies
the macros should be defined since the GCC header only considers
__STDC_WANT_IEC_60559_BFP_EXT__ (and for glibc systems, the
definitions in GCC's <stdint.h> will only be used with
-ffreestanding).

Tested for x86_64 and x86.

	* include/limits.h: Define
	__GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION and include
	<bits/libc-header-start.h> instead of including <features.h>.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (CHAR_WIDTH): New macro.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (SCHAR_WIDTH): Likewise.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (UCHAR_WIDTH): Likewise.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (SHRT_WIDTH): Likewise.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (USHRT_WIDTH): Likewise.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (INT_WIDTH): Likewise.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (UINT_WIDTH): Likewise.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (LONG_WIDTH): Likewise.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (ULONG_WIDTH): Likewise.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (LLONG_WIDTH): Likewise.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (ULLONG_WIDTH): Likewise.
	* manual/lang.texi (Width of Type): Document these macros.
	* stdlib/tst-width.c: New file.
	* stdlib/Makefile (tests): Add tst-width.

1 files changed, 87 insertions, 0 deletions

diff --git a/stdlib/tst-width.c b/stdlib/tst-width.c
new file mode 100644
index 0000000..4972c8d
--- /dev/null
+++ b/stdlib/tst-width.c
@@ -0,0 +1,87 @@
+/* Test integer width macros.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <limits.h>
+#include <stdio.h>
+
+#define CHECK_WIDTH(TYPE, MAX, WIDTH)					\
+  do									\
+    {									\
+      if ((MAX >> ((TYPE) -1 < 0 ? (WIDTH - 2) : (WIDTH - 1))) != 1)	\
+	{								\
+	  puts ("bad width of " #TYPE);					\
+	  result = 1;							\
+	}								\
+      else								\
+	puts ("width of " #TYPE " OK");					\
+    }									\
+  while (0)
+
+static int
+do_test (void)
+{
+  int result = 0;
+#ifndef CHAR_WIDTH
+# error "missing CHAR_WIDTH"
+#endif
+  CHECK_WIDTH (char, CHAR_MAX, CHAR_WIDTH);
+#ifndef SCHAR_WIDTH
+# error "missing SCHAR_WIDTH"
+#endif
+  CHECK_WIDTH (signed char, SCHAR_MAX, SCHAR_WIDTH);
+#ifndef UCHAR_WIDTH
+# error "missing UCHAR_WIDTH"
+#endif
+  CHECK_WIDTH (unsigned char, UCHAR_MAX, UCHAR_WIDTH);
+#ifndef SHRT_WIDTH
+# error "missing SHRT_WIDTH"
+#endif
+  CHECK_WIDTH (signed short, SHRT_MAX, SHRT_WIDTH);
+#ifndef USHRT_WIDTH
+# error "missing USHRT_WIDTH"
+#endif
+  CHECK_WIDTH (unsigned short, USHRT_MAX, USHRT_WIDTH);
+#ifndef INT_WIDTH
+# error "missing INT_WIDTH"
+#endif
+  CHECK_WIDTH (signed int, INT_MAX, INT_WIDTH);
+#ifndef UINT_WIDTH
+# error "missing UINT_WIDTH"
+#endif
+  CHECK_WIDTH (unsigned int, UINT_MAX, UINT_WIDTH);
+#ifndef LONG_WIDTH
+# error "missing LONG_WIDTH"
+#endif
+  CHECK_WIDTH (signed long, LONG_MAX, LONG_WIDTH);
+#ifndef ULONG_WIDTH
+# error "missing ULONG_WIDTH"
+#endif
+  CHECK_WIDTH (unsigned long, ULONG_MAX, ULONG_WIDTH);
+#ifndef LLONG_WIDTH
+# error "missing LLONG_WIDTH"
+#endif
+  CHECK_WIDTH (signed long long, LLONG_MAX, LLONG_WIDTH);
+#ifndef ULLONG_WIDTH
+# error "missing ULLONG_WIDTH"
+#endif
+  CHECK_WIDTH (unsigned long long, ULLONG_MAX, ULLONG_WIDTH);
+  return result;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"