The current definition of __WCHAR_MIN and __WCHAR_MAX are only correct
when wchar_t is an int. This is not the case on ARM/AArch64 where
wchar_t is an unsigned int, or some other architectures where wchar_t
is a long.
The current incorrect definition causes a build issue for example when
building mpd, which uses boost, with gcc 12.x:
In file included from
/home/thomas/buildroot/aarch64/host/aarch64-buildroot-linux-uclibc/sysroot/usr/include/boost/integer.hpp:20,
from
/home/thomas/buildroot/aarch64/host/aarch64-buildroot-linux-uclibc/sysroot/usr/include/boost/crc.hpp:42,
from ../src/storage/StorageState.cxx:43:
/home/thomas/buildroot/aarch64/host/aarch64-buildroot-linux-uclibc/sysroot/usr/include/boost/integer_traits.hpp:105:69:
error: narrowing conversion of ‘-2147483648’ from ‘int’ to ‘wchar_t’
[-Wnarrowing]
105 | public detail::integer_traits_base<wchar_t, WCHAR_MIN, WCHAR_MAX>
| ^
This issue was fixed in glibc in 2013, see bug report
https://sourceware.org/bugzilla/show_bug.cgi?id=15036, and upstream
commit
https://sourceware.org/git/?p=glibc.git;a=commit;h=052aff95782fefe9c63566471063e8b20836bfb8.
Since the i386-specific definition of __WCHAR_MIN and __WCHAR_MAX was
also removed at the same time in glibc, we do the same as part of this
commit.
Reported-by: Clément Ramirez <clement.rami...@bootlin.com>
With-some-useful-help-from: Paul Kocialkowski <paul.kocialkow...@bootlin.com>
Signed-off-by: Thomas Petazzoni <thomas.petazz...@bootlin.com>
---
libc/sysdeps/linux/common/bits/wchar.h | 32 ++++++++++++++++++++++----
libc/sysdeps/linux/i386/bits/wchar.h | 25 --------------------
2 files changed, 28 insertions(+), 29 deletions(-)
delete mode 100644 libc/sysdeps/linux/i386/bits/wchar.h
diff --git a/libc/sysdeps/linux/common/bits/wchar.h
b/libc/sysdeps/linux/common/bits/wchar.h
index a3ff5319e..50c7ef37b 100644
--- a/libc/sysdeps/linux/common/bits/wchar.h
+++ b/libc/sysdeps/linux/common/bits/wchar.h
@@ -1,5 +1,5 @@
/* wchar_t type related definitions.
- Copyright (C) 2000 Free Software Foundation, Inc.
+ Copyright (C) 2000-2022 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
@@ -14,12 +14,36 @@
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/>. */
+ <https://www.gnu.org/licenses/>. */
#ifndef _BITS_WCHAR_H
#define _BITS_WCHAR_H 1
-#define __WCHAR_MIN (-2147483647 - 1)
-#define __WCHAR_MAX (2147483647)
+/* The fallback definitions, for when __WCHAR_MAX__ or __WCHAR_MIN__
+ are not defined, give the right value and type as long as both int
+ and wchar_t are 32-bit types. Adding L'\0' to a constant value
+ ensures that the type is correct; it is necessary to use (L'\0' +
+ 0) rather than just L'\0' so that the type in C++ is the promoted
+ version of wchar_t rather than the distinct wchar_t type itself.
+ Because wchar_t in preprocessor #if expressions is treated as
+ intmax_t or uintmax_t, the expression (L'\0' - 1) would have the
+ wrong value for WCHAR_MAX in such expressions and so cannot be used
+ to define __WCHAR_MAX in the unsigned case. */
+
+#ifdef __WCHAR_MAX__
+# define __WCHAR_MAX __WCHAR_MAX__
+#elif L'\0' - 1 > 0
+# define __WCHAR_MAX (0xffffffffu + L'\0')
+#else
+# define __WCHAR_MAX (0x7fffffff + L'\0')
+#endif
+
+#ifdef __WCHAR_MIN__
+# define __WCHAR_MIN __WCHAR_MIN__
+#elif L'\0' - 1 > 0
+# define __WCHAR_MIN (L'\0' + 0)
+#else
+# define __WCHAR_MIN (-__WCHAR_MAX - 1)
+#endif
#endif /* bits/wchar.h */
diff --git a/libc/sysdeps/linux/i386/bits/wchar.h
b/libc/sysdeps/linux/i386/bits/wchar.h
deleted file mode 100644
index b94fc7a3f..000000000
--- a/libc/sysdeps/linux/i386/bits/wchar.h
+++ /dev/null
@@ -1,25 +0,0 @@
-/* wchar_t type related definitions.
- Copyright (C) 2000 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/>. */
-
-#ifndef _BITS_WCHAR_H
-#define _BITS_WCHAR_H 1
-
-#define __WCHAR_MIN (-2147483647l - 1l)
-#define __WCHAR_MAX (2147483647l)
-
-#endif /* bits/wchar.h */
--
2.41.0
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