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.

3 files changed, 37 insertions, 13 deletions

diff --git a/wcsmbs/Makefile b/wcsmbs/Makefile
index 653e289663..3ee91d2e1a 100644
--- a/wcsmbs/Makefile
+++ b/wcsmbs/Makefile
@@ -50,7 +50,7 @@ strop-tests :=  wcscmp wcsncmp wmemcmp wcslen wcschr wcsrchr wcscpy wcsnlen \
 tests := tst-wcstof wcsmbs-tst1 tst-wcsnlen tst-btowc tst-mbrtowc \
 	 tst-wcrtomb tst-wcpncpy tst-mbsrtowcs tst-wchar-h tst-mbrtowc2 \
 	 tst-c16c32-1 wcsatcliff tst-wcstol-locale tst-wcstod-nan-locale \
-	 tst-wcstod-round \
+	 tst-wcstod-round test-char-types \
 	 $(addprefix test-,$(strop-tests))
 
 include ../Rules
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>
diff --git a/wcsmbs/uchar.h b/wcsmbs/uchar.h
index 4d78f70fa2..4d9b2ec14d 100644
--- a/wcsmbs/uchar.h
+++ b/wcsmbs/uchar.h
@@ -28,20 +28,13 @@
 #define __need_size_t
 #include <stddef.h>
 
+#include <bits/types.h>
 #include <bits/types/mbstate_t.h>
 
-#if defined __GNUC__ && !defined __USE_ISOCXX11
-/* Define the 16-bit and 32-bit character types.  Use the information
-   provided by the compiler.  */
-# if !defined __CHAR16_TYPE__ || !defined __CHAR32_TYPE__
-#  if defined __STDC_VERSION__ && __STDC_VERSION__ < 201000L
-#   error "<uchar.h> requires ISO C11 mode"
-#  else
-#   error "definitions of __CHAR16_TYPE__ and/or __CHAR32_TYPE__ missing"
-#  endif
-# endif
-typedef __CHAR16_TYPE__ char16_t;
-typedef __CHAR32_TYPE__ char32_t;
+#ifndef __USE_ISOCXX11
+/* Define the 16-bit and 32-bit character types.  */
+typedef __uint_least16_t char16_t;
+typedef __uint_least32_t char32_t;
 #endif