Define char16_t, char32_t consistently with uint_least16_t, uint_least32_t (bug 17979).

As noted in bug 17979 (and as I noted earlier in
<https://sourceware.org/ml/libc-alpha/2012-02/msg00647.html>), uchar.h
has gratuitously complicated code to determine the types for char16_t
and char32_t, and to reject including that header for pre-C11
compilers not defining __CHAR16_TYPE__ and __CHAR32_TYPE__.  Since
those types are always required to match uint_least16_t and
uint_least32_t, which glibc knows how to define without reference to
such predefined macros, it's safe just to define those types the same
as the *least* types are defined in stdint.h, so allowing the header
to work with (for example) GCC 4.3.

This patch implements that.  bits/types.h is made to define
__int_leastN_t and __uint_leastN_t so the logic for those types can
stay in a single place, and stdint.h is made to use those __*_t to
define the public *_t types.  uchar.h is then made to use
__uint_least16_t and __uint_least32_t to define char16_t and char32_t,
so simplifying the logic there.  A new test is added that verifies the
types chosen for char16_t and char32_t do indeed match the types the
compiler uses for u"" and U"" string literals.

Tested for x86_64.  (I have not tested with any of the older compilers
for which this would actually make a difference to whether you can
include uchar.h.)

	[BZ #17979]
	* posix/bits/types.h (__int_least8_t): New typedef.
	(__uint_least8_t): Likewise.
	(__int_least16_t): Likewise.
	(__uint_least16_t): Likewise.
	(__int_least32_t): Likewise.
	(__uint_least32_t): Likewise.
	(__int_least64_t): Likewise.
	(__uint_least64_t): Likewise.
	* sysdeps/generic/stdint.h (int_least8_t): Define using
	__int_least8_t.
	(int_least16_t): Define using __int_least16_t.
	(int_least32_t): Define using __int_least32_t.
	(int_least64_t): Define using __int_least64_t.
	(uint_least8_t): Define using __uint_least8_t.
	(uint_least16_t): Define using __uint_least16_t.
	(uint_least32_t): Define using __uint_least32_t.
	(uint_least64_t): Define using __uint_least64_t.
	* wcsmbs/uchar.h: Include <bits/types.h>.
	(char16_t): Define using __uint_least16_t conditional only on
	[!__USE_ISOCXX11].
	(char32_t): Define using __uint_least32_t conditional only on
	[!__USE_ISOCXX11].
	* wcsmbs/test-char-types.c: New file.
	* wcsmbs/Makefile (tests): Add test-char-types.

1 files changed, 31 insertions, 0 deletions

diff --git a/wcsmbs/test-char-types.c b/wcsmbs/test-char-types.c
new file mode 100644
index 0000000000..31237619d2
--- /dev/null
+++ b/wcsmbs/test-char-types.c
@@ -0,0 +1,31 @@
+/* Test char16_t and char32_t types consistent with compiler.
+   Copyright (C) 2018 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 <uchar.h>
+
+const char16_t *s16 = u"";
+const char32_t *s32 = U"";
+
+static int
+do_test (void)
+{
+  /* This is a compilation test.  */
+  return 0;
+}
+
+#include <support/test-driver.c>