Split up endian.h to minimize exposure of BYTE_ORDER.

With only two exceptions (sys/types.h and sys/param.h, both of which
historically might have defined BYTE_ORDER) the public headers that
include <endian.h> only want to be able to test __BYTE_ORDER against
__*_ENDIAN.

This patch creates a new bits/endian.h that can be included by any
header that wants to be able to test __BYTE_ORDER and/or
__FLOAT_WORD_ORDER against the __*_ENDIAN constants, or needs
__LONG_LONG_PAIR.  It only defines macros in the implementation
namespace.

The existing bits/endian.h (which could not be included independently
of endian.h, and only defines __BYTE_ORDER and maybe __FLOAT_WORD_ORDER)
is renamed to bits/endianness.h.  I also took the opportunity to
canonicalize the form of this header, which we are stuck with having
one copy of per architecture.  Since they are so short, this means git
doesn’t understand that they were renamed from existing headers, sigh.

endian.h itself is a nonstandard header and its only remaining use
from a standard header is guarded by __USE_MISC, so I dropped the
__USE_MISC conditionals from around all of the public-namespace things
it defines.  (This means, an application that requests strict library
conformance but includes endian.h will still see the definition of
BYTE_ORDER.)

A few changes to specific bits/endian(ness).h variants deserve
mention:

 - sysdeps/unix/sysv/linux/ia64/bits/endian.h is moved to
   sysdeps/ia64/bits/endianness.h.  If I remember correctly, ia64 did
   have selectable endianness, but we have assembly code in
   sysdeps/ia64 that assumes it’s little-endian, so there is no reason
   to treat the ia64 endianness.h as linux-specific.

 - The C-SKY port does not fully support big-endian mode, the compile
   will error out if __CSKYBE__ is defined.

 - The PowerPC port had extra logic in its bits/endian.h to detect a
   broken compiler, which strikes me as unnecessary, so I removed it.

 - The only files that defined __FLOAT_WORD_ORDER always defined it to
   the same value as __BYTE_ORDER, so I removed those definitions.
   The SH bits/endian(ness).h had comments inconsistent with the
   actual setting of __FLOAT_WORD_ORDER, which I also removed.

 - I *removed* copyright boilerplate from the few bits/endian(ness).h
   headers that had it; these files record a single fact in a fashion
   dictated by an external spec, so I do not think they are copyrightable.

As long as I was changing every copy of ieee754.h in the tree, I
noticed that only the MIPS variant includes float.h, because it uses
LDBL_MANT_DIG to decide among three different versions of
ieee854_long_double.  This patch makes it not include float.h when
GCC’s intrinsic __LDBL_MANT_DIG__ is available.

	* string/endian.h: Unconditionally define LITTLE_ENDIAN,
	BIG_ENDIAN, PDP_ENDIAN, and BYTE_ORDER.	 Condition byteswapping
	macros only on !__ASSEMBLER__.	Move the definitions of
	__BIG_ENDIAN, __LITTLE_ENDIAN, __PDP_ENDIAN, __FLOAT_WORD_ORDER,
	and __LONG_LONG_PAIR to...
	* string/bits/endian.h: ...this new file, which includes
	the renamed header bits/endianness.h for the definition of
	__BYTE_ORDER and possibly __FLOAT_WORD_ORDER.

	* string/Makefile: Install bits/endianness.h.
	* include/bits/endian.h: New wrapper.

	* bits/endian.h: Rename to bits/endianness.h.
	Add multiple-include guard.  Rewrite the comment explaining what
	the machine-specific variants of this file should do.

	* sysdeps/unix/sysv/linux/ia64/bits/endian.h:
	Move to sysdeps/ia64.

	* sysdeps/aarch64/bits/endian.h
	* sysdeps/alpha/bits/endian.h
	* sysdeps/arm/bits/endian.h
	* sysdeps/csky/bits/endian.h
	* sysdeps/hppa/bits/endian.h
	* sysdeps/ia64/bits/endian.h
	* sysdeps/m68k/bits/endian.h
	* sysdeps/microblaze/bits/endian.h
	* sysdeps/mips/bits/endian.h
	* sysdeps/nios2/bits/endian.h
	* sysdeps/powerpc/bits/endian.h
	* sysdeps/riscv/bits/endian.h
	* sysdeps/s390/bits/endian.h
	* sysdeps/sh/bits/endian.h
	* sysdeps/sparc/bits/endian.h
	* sysdeps/x86/bits/endian.h:
	Rename to endianness.h; canonicalize form of file; remove
	redundant definitions of __FLOAT_WORD_ORDER.

	* sysdeps/powerpc/bits/endianness.h: Remove logic to check for
	broken compilers.

	* ctype/ctype.h
	* sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h
	* sysdeps/arm/nptl/bits/pthreadtypes-arch.h
	* sysdeps/csky/nptl/bits/pthreadtypes-arch.h
	* sysdeps/ia64/ieee754.h
	* sysdeps/ieee754/ieee754.h
	* sysdeps/ieee754/ldbl-128/ieee754.h
	* sysdeps/ieee754/ldbl-128ibm/ieee754.h
	* sysdeps/m68k/nptl/bits/pthreadtypes-arch.h
	* sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h
	* sysdeps/mips/ieee754/ieee754.h
	* sysdeps/mips/nptl/bits/pthreadtypes-arch.h
	* sysdeps/nios2/nptl/bits/pthreadtypes-arch.h
	* sysdeps/nptl/pthread.h
	* sysdeps/riscv/nptl/bits/pthreadtypes-arch.h
	* sysdeps/sh/nptl/bits/pthreadtypes-arch.h
	* sysdeps/sparc/sparc32/ieee754.h
	* sysdeps/unix/sysv/linux/generic/bits/stat.h
	* sysdeps/unix/sysv/linux/generic/bits/statfs.h
	* sysdeps/unix/sysv/linux/sys/acct.h
	* wctype/bits/wctype-wchar.h:
	Include bits/endian.h, not endian.h.

	* sysdeps/unix/sysv/linux/hppa/pthread.h: Don’t include endian.h.

	* sysdeps/mips/ieee754/ieee754.h: Use __LDBL_MANT_DIG__
	in ifdefs, instead of LDBL_MANT_DIG.  Only include float.h
	when __LDBL_MANT_DIG__ is not predefined, in which case
	define __LDBL_MANT_DIG__ to equal LDBL_MANT_DIG.

52 files changed, 241 insertions, 238 deletions

diff --git a/sysdeps/aarch64/bits/endian.h b/sysdeps/aarch64/bits/endian.h
deleted file mode 100644
index 03801d312a..0000000000
--- a/sysdeps/aarch64/bits/endian.h
+++ /dev/null
@@ -1,30 +0,0 @@
-/* Copyright (C) 1997-2019 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
-   <https://www.gnu.org/licenses/>.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-/* AArch64 can be either big or little endian.  */
-#ifdef __AARCH64EB__
-# define __BYTE_ORDER __BIG_ENDIAN
-#else
-# define __BYTE_ORDER __LITTLE_ENDIAN
-#endif
-
-#define __FLOAT_WORD_ORDER __BYTE_ORDER
diff --git a/sysdeps/aarch64/bits/endianness.h b/sysdeps/aarch64/bits/endianness.h
new file mode 100644
index 0000000000..300ebc8f9c
--- /dev/null
+++ b/sysdeps/aarch64/bits/endianness.h
@@ -0,0 +1,15 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* AArch64 has selectable endianness.  */
+#ifdef __AARCH64EB__
+# define __BYTE_ORDER __BIG_ENDIAN
+#else
+# define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h b/sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h
index 4cf3a68927..758b127a1a 100644
--- a/sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #ifdef __ILP32__
 # define __SIZEOF_PTHREAD_ATTR_T        32
diff --git a/sysdeps/alpha/bits/endian.h b/sysdeps/alpha/bits/endian.h
deleted file mode 100644
index 8a16e14e24..0000000000
--- a/sysdeps/alpha/bits/endian.h
+++ /dev/null
@@ -1,7 +0,0 @@
-/* Alpha is little-endian.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __LITTLE_ENDIAN
diff --git a/sysdeps/alpha/bits/endianness.h b/sysdeps/alpha/bits/endianness.h
new file mode 100644
index 0000000000..69f9a147f6
--- /dev/null
+++ b/sysdeps/alpha/bits/endianness.h
@@ -0,0 +1,11 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* Alpha is little-endian.  */
+#define __BYTE_ORDER __LITTLE_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/arm/bits/endian.h b/sysdeps/arm/bits/endian.h
deleted file mode 100644
index f49f6ab1c9..0000000000
--- a/sysdeps/arm/bits/endian.h
+++ /dev/null
@@ -1,10 +0,0 @@
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-/* ARM can be either big or little endian.  */
-#ifdef __ARMEB__
-#define __BYTE_ORDER __BIG_ENDIAN
-#else
-#define __BYTE_ORDER __LITTLE_ENDIAN
-#endif
diff --git a/sysdeps/arm/bits/endianness.h b/sysdeps/arm/bits/endianness.h
new file mode 100644
index 0000000000..2d671fff66
--- /dev/null
+++ b/sysdeps/arm/bits/endianness.h
@@ -0,0 +1,15 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* ARM has selectable endianness.  */
+#ifdef __ARMEB__
+#define __BYTE_ORDER __BIG_ENDIAN
+#else
+#define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/arm/nptl/bits/pthreadtypes-arch.h b/sysdeps/arm/nptl/bits/pthreadtypes-arch.h
index 70419c99f6..78b37eb5b8 100644
--- a/sysdeps/arm/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/arm/nptl/bits/pthreadtypes-arch.h
@@ -18,7 +18,7 @@
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #define __SIZEOF_PTHREAD_ATTR_T 36
 #define __SIZEOF_PTHREAD_MUTEX_T 24
diff --git a/sysdeps/csky/bits/endian.h b/sysdeps/csky/bits/endian.h
deleted file mode 100644
index 51df38d8f9..0000000000
--- a/sysdeps/csky/bits/endian.h
+++ /dev/null
@@ -1,9 +0,0 @@
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#ifdef __CSKYBE__
-# error "Big endian not supported for C-SKY."
-#else
-# define __BYTE_ORDER __LITTLE_ENDIAN
-#endif
diff --git a/sysdeps/csky/bits/endianness.h b/sysdeps/csky/bits/endianness.h
new file mode 100644
index 0000000000..ad20cf64e0
--- /dev/null
+++ b/sysdeps/csky/bits/endianness.h
@@ -0,0 +1,14 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+#ifdef __CSKYBE__
+# error "Big endian not supported for C-SKY."
+#else
+# define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/csky/nptl/bits/pthreadtypes-arch.h b/sysdeps/csky/nptl/bits/pthreadtypes-arch.h
index 5260c58d37..58be51dcfd 100644
--- a/sysdeps/csky/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/csky/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #define __SIZEOF_PTHREAD_ATTR_T			36
 #define __SIZEOF_PTHREAD_MUTEX_T		24
diff --git a/sysdeps/hppa/bits/endian.h b/sysdeps/hppa/bits/endian.h
deleted file mode 100644
index 585db0c0fa..0000000000
--- a/sysdeps/hppa/bits/endian.h
+++ /dev/null
@@ -1,7 +0,0 @@
-/* hppa1.1 big-endian.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __BIG_ENDIAN
diff --git a/sysdeps/hppa/bits/endianness.h b/sysdeps/hppa/bits/endianness.h
new file mode 100644
index 0000000000..96fd5ae5ef
--- /dev/null
+++ b/sysdeps/hppa/bits/endianness.h
@@ -0,0 +1,11 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* HP-PA is big-endian.  */
+#define __BYTE_ORDER __BIG_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/ia64/bits/endianness.h b/sysdeps/ia64/bits/endianness.h
new file mode 100644
index 0000000000..70c211e569
--- /dev/null
+++ b/sysdeps/ia64/bits/endianness.h
@@ -0,0 +1,11 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* IA64 is little-endian.  */
+#define __BYTE_ORDER __LITTLE_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/ia64/ieee754.h b/sysdeps/ia64/ieee754.h
index 21c4149ba2..610631a71d 100644
--- a/sysdeps/ia64/ieee754.h
+++ b/sysdeps/ia64/ieee754.h
@@ -16,11 +16,11 @@
    <https://www.gnu.org/licenses/>.  */
 
 #ifndef _IEEE754_H
-
 #define _IEEE754_H 1
+
 #include <features.h>
 
-#include <endian.h>
+#include <bits/endian.h>
 
 __BEGIN_DECLS
 
diff --git a/sysdeps/ieee754/ieee754.h b/sysdeps/ieee754/ieee754.h
index 581fe5c9de..7605d0d321 100644
--- a/sysdeps/ieee754/ieee754.h
+++ b/sysdeps/ieee754/ieee754.h
@@ -16,11 +16,11 @@
    <https://www.gnu.org/licenses/>.  */
 
 #ifndef _IEEE754_H
-
 #define _IEEE754_H 1
+
 #include <features.h>
 
-#include <endian.h>
+#include <bits/endian.h>
 
 __BEGIN_DECLS
 
diff --git a/sysdeps/ieee754/ldbl-128/ieee754.h b/sysdeps/ieee754/ldbl-128/ieee754.h
index 87dc1d781d..47f11d8a6b 100644
--- a/sysdeps/ieee754/ldbl-128/ieee754.h
+++ b/sysdeps/ieee754/ldbl-128/ieee754.h
@@ -16,11 +16,11 @@
    <https://www.gnu.org/licenses/>.  */
 
 #ifndef _IEEE754_H
-
 #define _IEEE754_H 1
+
 #include <features.h>
 
-#include <endian.h>
+#include <bits/endian.h>
 
 __BEGIN_DECLS
 
diff --git a/sysdeps/ieee754/ldbl-128ibm/ieee754.h b/sysdeps/ieee754/ldbl-128ibm/ieee754.h
index 35f22895e6..606b4c7d8a 100644
--- a/sysdeps/ieee754/ldbl-128ibm/ieee754.h
+++ b/sysdeps/ieee754/ldbl-128ibm/ieee754.h
@@ -16,11 +16,11 @@
    <https://www.gnu.org/licenses/>.  */
 
 #ifndef _IEEE754_H
-
 #define _IEEE754_H 1
+
 #include <features.h>
 
-#include <endian.h>
+#include <bits/endian.h>
 
 __BEGIN_DECLS
 
diff --git a/sysdeps/m68k/bits/endian.h b/sysdeps/m68k/bits/endian.h
deleted file mode 100644
index bf4ecb60a4..0000000000
--- a/sysdeps/m68k/bits/endian.h
+++ /dev/null
@@ -1,7 +0,0 @@
-/* m68k is big-endian.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __BIG_ENDIAN
diff --git a/sysdeps/m68k/bits/endianness.h b/sysdeps/m68k/bits/endianness.h
new file mode 100644
index 0000000000..7e5f0d2969
--- /dev/null
+++ b/sysdeps/m68k/bits/endianness.h
@@ -0,0 +1,11 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* m68k is big-endian.  */
+#define __BYTE_ORDER __BIG_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/m68k/nptl/bits/pthreadtypes-arch.h b/sysdeps/m68k/nptl/bits/pthreadtypes-arch.h
index 8199076399..792cb32289 100644
--- a/sysdeps/m68k/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/m68k/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #define __SIZEOF_PTHREAD_ATTR_T 36
 #define __SIZEOF_PTHREAD_MUTEX_T 24
diff --git a/sysdeps/microblaze/bits/endian.h b/sysdeps/microblaze/bits/endian.h
deleted file mode 100644
index 6e961a5547..0000000000
--- a/sysdeps/microblaze/bits/endian.h
+++ /dev/null
@@ -1,30 +0,0 @@
-/* Copyright (C) 1997-2019 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
-   <https://www.gnu.org/licenses/>.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-/* MicroBlaze can be either big or little endian.  */
-#ifdef _BIG_ENDIAN
-# define __BYTE_ORDER __BIG_ENDIAN
-# define __FLOAT_WORD_ORDER __BIG_ENDIAN
-#else
-# define __BYTE_ORDER __LITTLE_ENDIAN
-# define __FLOAT_WORD_ORDER __LITTLE_ENDIAN
-#endif
diff --git a/sysdeps/microblaze/bits/endianness.h b/sysdeps/microblaze/bits/endianness.h
new file mode 100644
index 0000000000..c4bb7e5f2e
--- /dev/null
+++ b/sysdeps/microblaze/bits/endianness.h
@@ -0,0 +1,15 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* MicroBlaze has selectable endianness.  */
+#ifdef _BIG_ENDIAN
+# define __BYTE_ORDER __BIG_ENDIAN
+#else
+# define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h b/sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h
index b1ae4aacdb..7cf1ff6a72 100644
--- a/sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 # define _BITS_PTHREADTYPES_ARCH_H	1
 
-# include <endian.h>
+# include <bits/endian.h>
 
 # define __SIZEOF_PTHREAD_ATTR_T         36
 # define __SIZEOF_PTHREAD_MUTEX_T        24
diff --git a/sysdeps/mips/bits/endian.h b/sysdeps/mips/bits/endian.h
deleted file mode 100644
index 126059799d..0000000000
--- a/sysdeps/mips/bits/endian.h
+++ /dev/null
@@ -1,15 +0,0 @@
-/* The MIPS architecture has selectable endianness.
-   It exists in both little and big endian flavours and we
-   want to be able to share the installed header files between
-   both, so we define __BYTE_ORDER based on GCC's predefines.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#ifdef __MIPSEB
-# define __BYTE_ORDER __BIG_ENDIAN
-#endif
-#ifdef __MIPSEL
-# define __BYTE_ORDER __LITTLE_ENDIAN
-#endif
diff --git a/sysdeps/mips/bits/endianness.h b/sysdeps/mips/bits/endianness.h
new file mode 100644
index 0000000000..09e138b89b
--- /dev/null
+++ b/sysdeps/mips/bits/endianness.h
@@ -0,0 +1,16 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* MIPS has selectable endianness.  */
+#ifdef __MIPSEB
+# define __BYTE_ORDER __BIG_ENDIAN
+#endif
+#ifdef __MIPSEL
+# define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/mips/ieee754/ieee754.h b/sysdeps/mips/ieee754/ieee754.h
index ebaf8d84c3..250fa5e8c0 100644
--- a/sysdeps/mips/ieee754/ieee754.h
+++ b/sysdeps/mips/ieee754/ieee754.h
@@ -16,13 +16,16 @@
    <https://www.gnu.org/licenses/>.  */
 
 #ifndef _IEEE754_H
-
 #define _IEEE754_H 1
+
 #include <features.h>
 
-#include <endian.h>
+#include <bits/endian.h>
 
-#include <float.h>
+#ifndef __LDBL_MANT_DIG__
+# include <float.h>
+# define __LDBL_MANT_DIG__ __LDBL_MANT_DIG__
+#endif
 
 __BEGIN_DECLS
 
@@ -127,7 +130,7 @@ union ieee754_double
 
 #define IEEE754_DOUBLE_BIAS	0x3ff /* Added to exponent.  */
 
-#if LDBL_MANT_DIG == 113
+#if __LDBL_MANT_DIG__ == 113
 
 union ieee854_long_double
   {
@@ -184,7 +187,7 @@ union ieee854_long_double
 
 #define IEEE854_LONG_DOUBLE_BIAS 0x3fff /* Added to exponent.  */
 
-#elif LDBL_MANT_DIG == 64
+#elif __LDBL_MANT_DIG__ == 64
 
 union ieee854_long_double
   {
@@ -253,7 +256,7 @@ union ieee854_long_double
 
 #define IEEE854_LONG_DOUBLE_BIAS 0x3fff
 
-#elif LDBL_MANT_DIG == 53
+#elif __LDBL_MANT_DIG__ == 53
 
 union ieee854_long_double
   {
@@ -316,7 +319,7 @@ union ieee854_long_double
 
 #define IEEE854_LONG_DOUBLE_BIAS	0x3ff /* Added to exponent.  */
 
-#endif /* LDBL_MANT_DIG == 53 */
+#endif /* __LDBL_MANT_DIG__ == 53 */
 
 __END_DECLS
 
diff --git a/sysdeps/mips/nptl/bits/pthreadtypes-arch.h b/sysdeps/mips/nptl/bits/pthreadtypes-arch.h
index b32e888ea5..0bb703511c 100644
--- a/sysdeps/mips/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/mips/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #if _MIPS_SIM == _ABI64
 # define __SIZEOF_PTHREAD_ATTR_T 56
diff --git a/sysdeps/nios2/bits/endian.h b/sysdeps/nios2/bits/endian.h
deleted file mode 100644
index 164f9e4d78..0000000000
--- a/sysdeps/nios2/bits/endian.h
+++ /dev/null
@@ -1,12 +0,0 @@
-/* The Nios II architecture has selectable endianness.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#ifdef __nios2_big_endian__
-# define __BYTE_ORDER __BIG_ENDIAN
-#endif
-#ifdef __nios2_little_endian__
-# define __BYTE_ORDER __LITTLE_ENDIAN
-#endif
diff --git a/sysdeps/nios2/bits/endianness.h b/sysdeps/nios2/bits/endianness.h
new file mode 100644
index 0000000000..87e66ebd71
--- /dev/null
+++ b/sysdeps/nios2/bits/endianness.h
@@ -0,0 +1,16 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* Nios II has selectable endianness.  */
+#ifdef __nios2_big_endian__
+# define __BYTE_ORDER __BIG_ENDIAN
+#endif
+#ifdef __nios2_little_endian__
+# define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/nios2/nptl/bits/pthreadtypes-arch.h b/sysdeps/nios2/nptl/bits/pthreadtypes-arch.h
index 8cd8bbedaf..dcd3499a86 100644
--- a/sysdeps/nios2/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/nios2/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #define __SIZEOF_PTHREAD_ATTR_T 36
 #define __SIZEOF_PTHREAD_MUTEX_T 24
diff --git a/sysdeps/nptl/pthread.h b/sysdeps/nptl/pthread.h
index ceb724d3a2..467b446aca 100644
--- a/sysdeps/nptl/pthread.h
+++ b/sysdeps/nptl/pthread.h
@@ -19,10 +19,10 @@
 #define _PTHREAD_H	1
 
 #include <features.h>
-#include <endian.h>
 #include <sched.h>
 #include <time.h>
 
+#include <bits/endian.h>
 #include <bits/pthreadtypes.h>
 #include <bits/setjmp.h>
 #include <bits/wordsize.h>
diff --git a/sysdeps/powerpc/bits/endian.h b/sysdeps/powerpc/bits/endian.h
deleted file mode 100644
index c82f7ad4de..0000000000
--- a/sysdeps/powerpc/bits/endian.h
+++ /dev/null
@@ -1,36 +0,0 @@
-/* Copyright (C) 1997-2019 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
-   <https://www.gnu.org/licenses/>.  */
-
-/* PowerPC can be little or big endian.  Hopefully gcc will know...  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#if defined __BIG_ENDIAN__ || defined _BIG_ENDIAN
-# if defined __LITTLE_ENDIAN__ || defined _LITTLE_ENDIAN
-#  error Both BIG_ENDIAN and LITTLE_ENDIAN defined!
-# endif
-# define __BYTE_ORDER __BIG_ENDIAN
-#else
-# if defined __LITTLE_ENDIAN__ || defined _LITTLE_ENDIAN
-#  define __BYTE_ORDER __LITTLE_ENDIAN
-# else
-#  warning Cannot determine current byte order, assuming big-endian.
-#  define __BYTE_ORDER __BIG_ENDIAN
-# endif
-#endif
diff --git a/sysdeps/powerpc/bits/endianness.h b/sysdeps/powerpc/bits/endianness.h
new file mode 100644
index 0000000000..3e7735237e
--- /dev/null
+++ b/sysdeps/powerpc/bits/endianness.h
@@ -0,0 +1,16 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* PowerPC has selectable endianness.  */
+#if defined __BIG_ENDIAN__ || defined _BIG_ENDIAN
+# define __BYTE_ORDER __BIG_ENDIAN
+#endif
+#if defined __LITTLE_ENDIAN__ || defined _LITTLE_ENDIAN
+# define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/riscv/bits/endian.h b/sysdeps/riscv/bits/endian.h
deleted file mode 100644
index 4aaf559d4f..0000000000
--- a/sysdeps/riscv/bits/endian.h
+++ /dev/null
@@ -1,5 +0,0 @@
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __LITTLE_ENDIAN
diff --git a/sysdeps/riscv/bits/endianness.h b/sysdeps/riscv/bits/endianness.h
new file mode 100644
index 0000000000..952d08595a
--- /dev/null
+++ b/sysdeps/riscv/bits/endianness.h
@@ -0,0 +1,11 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* RISC-V is little-endian.  */
+#define __BYTE_ORDER __LITTLE_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/riscv/nptl/bits/pthreadtypes-arch.h b/sysdeps/riscv/nptl/bits/pthreadtypes-arch.h
index 583443954e..33f0ee43fe 100644
--- a/sysdeps/riscv/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/riscv/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #if __riscv_xlen == 64
 # define __SIZEOF_PTHREAD_ATTR_T 		56
diff --git a/sysdeps/s390/bits/endian.h b/sysdeps/s390/bits/endian.h
deleted file mode 100644
index ac27f0119a..0000000000
--- a/sysdeps/s390/bits/endian.h
+++ /dev/null
@@ -1,7 +0,0 @@
-/* s390 is big-endian */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __BIG_ENDIAN
diff --git a/sysdeps/s390/bits/endianness.h b/sysdeps/s390/bits/endianness.h
new file mode 100644
index 0000000000..c2d34e1c3e
--- /dev/null
+++ b/sysdeps/s390/bits/endianness.h
@@ -0,0 +1,11 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* S/390 is big-endian.  */
+#define __BYTE_ORDER __BIG_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/sh/bits/endian.h b/sysdeps/sh/bits/endian.h
deleted file mode 100644
index 1fef1ff938..0000000000
--- a/sysdeps/sh/bits/endian.h
+++ /dev/null
@@ -1,13 +0,0 @@
-/* SH is bi-endian but with a big-endian FPU.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#ifdef __LITTLE_ENDIAN__
-#define __BYTE_ORDER __LITTLE_ENDIAN
-#define __FLOAT_WORD_ORDER __LITTLE_ENDIAN
-#else
-#define __BYTE_ORDER __BIG_ENDIAN
-#define __FLOAT_WORD_ORDER __BIG_ENDIAN
-#endif
diff --git a/sysdeps/sh/bits/endianness.h b/sysdeps/sh/bits/endianness.h
new file mode 100644
index 0000000000..45c7c83a63
--- /dev/null
+++ b/sysdeps/sh/bits/endianness.h
@@ -0,0 +1,15 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* SH has selectable endianness.  */
+#ifdef __LITTLE_ENDIAN__
+#define __BYTE_ORDER __LITTLE_ENDIAN
+#else
+#define __BYTE_ORDER __BIG_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/sh/nptl/bits/pthreadtypes-arch.h b/sysdeps/sh/nptl/bits/pthreadtypes-arch.h
index 6c9485d989..219a861398 100644
--- a/sysdeps/sh/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/sh/nptl/bits/pthreadtypes-arch.h
@@ -18,7 +18,7 @@
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #define __SIZEOF_PTHREAD_ATTR_T 36
 #define __SIZEOF_PTHREAD_MUTEX_T 24
diff --git a/sysdeps/sparc/bits/endian.h b/sysdeps/sparc/bits/endianness.h
index 8acfdf5df6..0b6f5bf8b2 100644
--- a/sysdeps/sparc/bits/endian.h
+++ b/sysdeps/sparc/bits/endianness.h
@@ -1,12 +1,16 @@
-/* Sparc is big-endian, but v9 supports endian conversion on loads/stores
-   and GCC supports such a mode.  Be prepared.  */
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
 
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
 #endif
 
+/* Sparc is big-endian, but v9 supports endian conversion on loads/stores
+   and GCC supports such a mode.  Be prepared.  */
 #ifdef __LITTLE_ENDIAN__
 # define __BYTE_ORDER __LITTLE_ENDIAN
 #else
 # define __BYTE_ORDER __BIG_ENDIAN
 #endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/sparc/sparc32/ieee754.h b/sysdeps/sparc/sparc32/ieee754.h
index 87dc1d781d..47f11d8a6b 100644
--- a/sysdeps/sparc/sparc32/ieee754.h
+++ b/sysdeps/sparc/sparc32/ieee754.h
@@ -16,11 +16,11 @@
    <https://www.gnu.org/licenses/>.  */
 
 #ifndef _IEEE754_H
-
 #define _IEEE754_H 1
+
 #include <features.h>
 
-#include <endian.h>
+#include <bits/endian.h>
 
 __BEGIN_DECLS
 
diff --git a/sysdeps/unix/sysv/linux/generic/bits/stat.h b/sysdeps/unix/sysv/linux/generic/bits/stat.h
index 62aeea5a88..1565f3f824 100644
--- a/sysdeps/unix/sysv/linux/generic/bits/stat.h
+++ b/sysdeps/unix/sysv/linux/generic/bits/stat.h
@@ -23,7 +23,7 @@
 #ifndef _BITS_STAT_H
 #define _BITS_STAT_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 #include <bits/wordsize.h>
 
 /* 64-bit libc uses the kernel's 'struct stat', accessed via the
diff --git a/sysdeps/unix/sysv/linux/generic/bits/statfs.h b/sysdeps/unix/sysv/linux/generic/bits/statfs.h
index 3472084ade..c4069aba62 100644
--- a/sysdeps/unix/sysv/linux/generic/bits/statfs.h
+++ b/sysdeps/unix/sysv/linux/generic/bits/statfs.h
@@ -20,7 +20,7 @@
 # error "Never include <bits/statfs.h> directly; use <sys/statfs.h> instead."
 #endif
 
-#include <endian.h>
+#include <bits/endian.h>
 #include <bits/types.h>
 #include <bits/wordsize.h>
 
diff --git a/sysdeps/unix/sysv/linux/hppa/pthread.h b/sysdeps/unix/sysv/linux/hppa/pthread.h
index e168901ba0..424135c800 100644
--- a/sysdeps/unix/sysv/linux/hppa/pthread.h
+++ b/sysdeps/unix/sysv/linux/hppa/pthread.h
@@ -19,7 +19,6 @@
 #define _PTHREAD_H	1
 
 #include <features.h>
-#include <endian.h>
 #include <sched.h>
 #include <time.h>
 
diff --git a/sysdeps/unix/sysv/linux/ia64/bits/endian.h b/sysdeps/unix/sysv/linux/ia64/bits/endian.h
deleted file mode 100644
index 98a5e23991..0000000000
--- a/sysdeps/unix/sysv/linux/ia64/bits/endian.h
+++ /dev/null
@@ -1,7 +0,0 @@
-/* Linux/ia64 is little-endian.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __LITTLE_ENDIAN
diff --git a/sysdeps/unix/sysv/linux/powerpc/htm.h b/sysdeps/unix/sysv/linux/powerpc/htm.h
index 75e3eb0397..f17d751013 100644
--- a/sysdeps/unix/sysv/linux/powerpc/htm.h
+++ b/sysdeps/unix/sysv/linux/powerpc/htm.h
@@ -50,7 +50,7 @@
 
 #else
 
-#include <endian.h>
+#include <bits/endian.h>
 
 /* Official HTM intrinsics interface matching GCC, but works
    on older GCC compatible compilers and binutils.
diff --git a/sysdeps/unix/sysv/linux/sys/acct.h b/sysdeps/unix/sysv/linux/sys/acct.h
index 5db43fd675..1d2f22402a 100644
--- a/sysdeps/unix/sysv/linux/sys/acct.h
+++ b/sysdeps/unix/sysv/linux/sys/acct.h
@@ -20,7 +20,7 @@
 
 #include <sys/types.h>
 #include <stdint.h>
-#include <endian.h>
+#include <bits/endian.h>
 #include <bits/types/time_t.h>
 
 __BEGIN_DECLS
diff --git a/sysdeps/x86/bits/endian.h b/sysdeps/x86/bits/endian.h
deleted file mode 100644
index 5a56c726f7..0000000000
--- a/sysdeps/x86/bits/endian.h
+++ /dev/null
@@ -1,7 +0,0 @@
-/* i386/x86_64 are little-endian.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __LITTLE_ENDIAN
diff --git a/sysdeps/x86/bits/endianness.h b/sysdeps/x86/bits/endianness.h
new file mode 100644
index 0000000000..962a9ae4d6
--- /dev/null
+++ b/sysdeps/x86/bits/endianness.h
@@ -0,0 +1,11 @@
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* i386/x86_64 are little-endian.  */
+#define __BYTE_ORDER __LITTLE_ENDIAN
+
+#endif /* bits/endianness.h */