Re: [PATCH] Fix up bswap_* types

Re: [PATCH] Fix up bswap_* types

[Marek Polacek]

On Wed, Aug 22, 2012 at 09:47:47AM -0700, Roland McGrath wrote:
> Some of your ChangeLog lines are too long (wrap at column 79 or
> before).  Otherwise it looks fine to me.  But please test an i686

I've fixed the CL.  But unfortunately I hadn't noticed that my patch
actually breaks stdlib/isomac test.  It fails with:

Tested files:
assert.h
ctype.h
#define INT16_C(c) c
#define UINTMAX_C(c) c ## UL
#define UINT16_C(c) c
#define INT64_C(c) c ## L
#define UINT64_C(c) c ## UL
#define INT8_C(c) c
#define INT32_C(c) c
#define UINT32_C(c) c ## U
#define UINT8_C(c) c
#define INTMAX_C(c) c ## L
errno.h
float.h
iso646.h
limits.h
locale.h
math.h
setjmp.h
signal.h
stdarg.h
stddef.h
stdio.h
stdlib.h
string.h
time.h
wchar.h
wctype.h
#define INT16_C(c) c
#define UINTMAX_C(c) c ## UL
#define UINT16_C(c) c
#define INT64_C(c) c ## L
#define UINT64_C(c) c ## UL
#define INT8_C(c) c
#define INT32_C(c) c
#define UINT32_C(c) c ## U
#define UINT8_C(c) c
#define INTMAX_C(c) c ## L

because {,w}ctype.h contains <endian.h> and
we end up including sysdeps/generic/stdint.h which defines macros above.
I've circumvent that by using #ifndef _ISOMAC guard around them.

Now tested both i?86 and x86_64.  Isomac doesn't yell this time around.
Ok for trunk?  CC'ing Andreas, ok for s390, too?  Thanks,

2012-08-22  Marek Polacek  <polacek@redhat.com>

	[BZ #14508]
	* sysdeps/generic/stdint.h: Exclude some macros if _ISOMAC is defined.
	* string/byteswap.h: Include <stdint.h>.
	* string/endian.h: Likewise.
	* bits/byteswap-16.h (__bswap_16) [__GNUC__]: Use uint16_t instead
	of unsigned short int.
	(__bswapt_16) [!__GNUC__]: Likewise.
	* bits/byteswap.h (__bswap_constant_16): Use uint16_t instead of
	unsigned short int.
	(__bswap_32) [__GNUC_PREREQ]: Use uint32_t instead of unsigned int.
	(__bswap_32) [!__GNUC_PREREQ]: Likewise.
	(__bswap_64) [__GNUC_PREREQ]: Use uint64_t instead of unsigned long
	long int.
	(__bswap_64) [!__GNUC_PREREQ]: Use uint64_t instead of unsigned long
	long int and uint32_t instead of unsigned int.
	(__bswap_64) [__GLIBC_HAVE_LONG_LONG]: Use uint64_t instead of
	unsigned long long int.
	* sysdeps/s390/bits/byteswap-16.h (__bswap_16) [WORDSIZE == 64]: Use
	uint16_t instead of unsigned short int.
	(__bswap_16) [!WORDSIZE == 64]: Likewise.
	(__bswap_16) [!__GNUC__]: Likewise.
	* sysdeps/s390/bits/byteswap.h (__bswap_32) [__GNUC_PREREQ]: Use
	uint32_t  instead of unsigned int.
	(__bswap_32) [!__GNUC_PREREQ]: Likewise.
	(__bswap_64) [__GNUC_PREREQ]: Use uint64_t instead of unsigned long
	long int.
	(__bswap_64) [!__GNUC_PREREQ]: Use uint64_t instead of unsigned long
	long int and uint32_t instead of unsigned int.
	(__bswap_64) [__GLIBC_HAVE_LONG_LONG]: Use uint64_t instead of
	unsigned long long int.
	(__bswap_constant_16): Use uint16_t instead of unsigned short int.
	* sysdeps/x86/bits/byteswap-16.h (__bswap_16) [WORDSIZE == 64]: Use
	uint16_t instead of unsigned short int.
	(__bswap_16) [!WORDSIZE == 64]: Likewise.
	(__bswap_16) [!__GNUC__]: Likewise.
	* sysdeps/x86/bits/byteswap.h (__bswap_32) [__GNUC_PREREQ]: Use
	uint32_t instead of unsigned int.
	(__bswap_32) [!__GNUC_PREREQ]: Likewise.
	(__bswap_64) [__GNUC_PREREQ]: Use uint64_t instead of unsigned long
	long int.
	(__bswap_64) [!__GNUC_PREREQ]: Use uint64_t instead of unsigned long
	long int and uint32_t instead of unsigned int.
	(__bswap_64) [__GLIBC_HAVE_LONG_LONG]: Use uint64_t instead of
	unsigned long long int.

--- libc/bits/byteswap-16.h.mp	2012-08-19 14:50:02.904713109 +0200
+++ libc/bits/byteswap-16.h	2012-08-22 19:52:49.218953619 +0200
@@ -23,11 +23,11 @@
 #ifdef __GNUC__
 # define __bswap_16(x) \
     (__extension__							      \
-     ({ unsigned short int __bsx = (unsigned short int) (x);		      \
+     ({ uint16_t __bsx = (uint16_t) (x);				      \
        __bswap_constant_16 (__bsx); }))
 #else
-static __inline unsigned short int
-__bswap_16 (unsigned short int __bsx)
+static __inline uint16_t
+__bswap_16 (uint16_t __bsx)
 {
   return __bswap_constant_16 (__bsx);
 }
--- libc/bits/byteswap.h.mp	2012-08-19 14:49:59.151703654 +0200
+++ libc/bits/byteswap.h	2012-08-22 19:52:49.223953637 +0200
@@ -1,5 +1,5 @@
 /* Macros to swap the order of bytes in integer values.
-   Copyright (C) 1997-2012  Free Software Foundation, Inc.
+   Copyright (C) 1997-2012 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
@@ -27,7 +27,7 @@
 
 /* Swap bytes in 16 bit value.  */
 #define __bswap_constant_16(x) \
-	((unsigned short int)((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8)))
+	((uint16_t) ((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8)))
 
 /* Get __bswap_16.  */
 #include <bits/byteswap-16.h>
@@ -39,19 +39,19 @@
 
 #ifdef __GNUC__
 # if __GNUC_PREREQ (4, 2)
-static __inline unsigned int
-__bswap_32 (unsigned int __bsx)
+static __inline uint32_t
+__bswap_32 (uint32_t __bsx)
 {
   return __builtin_bswap32 (__bsx);
 }
 # else
 #  define __bswap_32(x) \
   (__extension__							      \
-   ({ register unsigned int __bsx = (x); __bswap_constant_32 (__bsx); }))
+   ({ register uint32_t __bsx = (x); __bswap_constant_32 (__bsx); }))
 # endif
 #else
-static __inline unsigned int
-__bswap_32 (unsigned int __bsx)
+static __inline uint32_t
+__bswap_32 (uint32_t __bsx)
 {
   return __bswap_constant_32 (__bsx);
 }
@@ -70,16 +70,16 @@ __bswap_32 (unsigned int __bsx)
 		     | (((x) & 0x00000000000000ffull) << 56)))
 
 # if __GNUC_PREREQ (4, 2)
-static __inline unsigned long long int
-__bswap_64 (unsigned long long int __bsx)
+static __inline uint64_t
+__bswap_64 (uint64_t __bsx)
 {
   return __builtin_bswap64 (__bsx);
 }
 # else
 #  define __bswap_64(x) \
      (__extension__							      \
-      ({ union { __extension__ unsigned long long int __ll;		      \
-		 unsigned int __l[2]; } __w, __r;			      \
+      ({ union { __extension__ uint64_t __ll;				      \
+		 uint32_t __l[2]; } __w, __r;				      \
 	 if (__builtin_constant_p (x))					      \
 	   __r.__ll = __bswap_constant_64 (x);				      \
 	 else								      \
@@ -101,8 +101,8 @@ __bswap_64 (unsigned long long int __bsx
       | (((x) & 0x000000000000ff00ull) << 40)				      \
       | (((x) & 0x00000000000000ffull) << 56))
 
-static __inline unsigned long long int
-__bswap_64 (unsigned long long int __bsx)
+static __inline uint64_t
+__bswap_64 (uint64_t __bsx)
 {
   return __bswap_constant_64 (__bsx);
 }
--- libc/string/byteswap.h.mp	2012-08-22 15:39:37.725254448 +0200
+++ libc/string/byteswap.h	2012-08-22 19:52:49.266953776 +0200
@@ -18,6 +18,7 @@
 #ifndef _BYTESWAP_H
 #define _BYTESWAP_H	1
 
+#include <stdint.h>
 #include <features.h>
 
 /* Get the machine specific, optimized definitions.  */
--- libc/string/endian.h.mp	2012-08-22 15:40:11.595335965 +0200
+++ libc/string/endian.h	2012-08-22 19:52:49.275953805 +0200
@@ -18,6 +18,7 @@
 #ifndef	_ENDIAN_H
 #define	_ENDIAN_H	1
 
+#include <stdint.h>
 #include <features.h>
 
 /* Definitions for byte order, according to significance of bytes,
--- libc/sysdeps/s390/bits/byteswap-16.h.mp	2012-08-19 16:34:38.626981852 +0200
+++ libc/sysdeps/s390/bits/byteswap-16.h	2012-08-22 19:52:49.353954060 +0200
@@ -28,11 +28,11 @@
 # if __WORDSIZE == 64
 #  define __bswap_16(x) \
      (__extension__							      \
-      ({ unsigned short int __v, __x = (unsigned short int) (x);	      \
+      ({ uint16_t __v, __x = (uint16_t) (x);				      \
 	 if (__builtin_constant_p (x))					      \
 	   __v = __bswap_constant_16 (__x);				      \
 	 else {								      \
-	   unsigned short int __tmp = (unsigned short int) (__x);             \
+	   uint16_t __tmp = (uint16_t) (__x);				      \
 	   __asm__ __volatile__ (                                             \
 	      "lrvh %0,%1"                                                    \
 	      : "=&d" (__v) : "m" (__tmp) );                                  \
@@ -41,11 +41,11 @@
 # else
 #  define __bswap_16(x) \
      (__extension__							      \
-      ({ unsigned short int __v, __x = (unsigned short int) (x);	      \
+      ({ uint16_t __v, __x = (uint16_t) (x);				      \
 	 if (__builtin_constant_p (x))					      \
 	   __v = __bswap_constant_16 (__x);				      \
 	 else {								      \
-	   unsigned short int __tmp = (unsigned short int) (__x);             \
+	   uint16_t __tmp = (uint16_t) (__x);				      \
 	   __asm__ __volatile__ (                                             \
 	      "sr   %0,%0\n"                                                  \
 	      "la   1,%1\n"                                                   \
@@ -57,8 +57,8 @@
 # endif
 #else
 /* This is better than nothing.  */
-static __inline unsigned short int
-__bswap_16 (unsigned short int __bsx)
+static __inline uint16_t
+__bswap_16 (uint16_t __bsx)
 {
   return __bswap_constant_16 (__bsx);
 }
--- libc/sysdeps/s390/bits/byteswap.h.mp	2012-08-19 16:22:27.367608050 +0200
+++ libc/sysdeps/s390/bits/byteswap.h	2012-08-22 19:52:49.378954140 +0200
@@ -27,7 +27,7 @@
 #define _BITS_BYTESWAP_H 1
 
 #define __bswap_constant_16(x) \
-	((unsigned short int) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
+	((uint16_t) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
 
 /* Get __bswap_16.  */
 #include <bits/byteswap-16.h>
@@ -41,11 +41,11 @@
 # if __WORDSIZE == 64
 #  define __bswap_32(x) \
      (__extension__							      \
-      ({ unsigned int __v, __x = (x);					      \
+      ({ uint32_t __v, __x = (x);					      \
 	 if (__builtin_constant_p (x))					      \
 	   __v = __bswap_constant_32 (__x);				      \
 	 else {								      \
-	   unsigned int __tmp = (unsigned int) (__x);                         \
+	   uint32_t __tmp = (uint32_t) (__x);				      \
 	   __asm__ __volatile__ (                                             \
 	      "lrv   %0,%1"                                                   \
 	      : "=&d" (__v) : "m" (__tmp));                                   \
@@ -54,11 +54,11 @@
 # else
 #  define __bswap_32(x) \
      (__extension__							      \
-      ({ unsigned int __v, __x = (x);					      \
+      ({ uint32_t __v, __x = (x);					      \
 	 if (__builtin_constant_p (x))					      \
 	   __v = __bswap_constant_32 (__x);				      \
 	 else {								      \
-	   unsigned int __tmp = (unsigned int) (__x);                         \
+	   uint32_t __tmp = (uint32_t) (__x);				      \
 	   __asm__ __volatile__ (                                             \
 	      "la    1,%1\n"                                                  \
 	      "icm   %0,8,3(1)\n"                                             \
@@ -70,8 +70,8 @@
 	 __v; }))
 # endif
 #else
-static __inline unsigned int
-__bswap_32 (unsigned int __bsx)
+static __inline uint32_t
+__bswap_32 (uint32_t __bsx)
 {
   return __bswap_constant_32 (__bsx);
 }
@@ -92,11 +92,11 @@ __bswap_32 (unsigned int __bsx)
 # if __WORDSIZE == 64
 #  define __bswap_64(x) \
      (__extension__							      \
-      ({ unsigned long __w, __x = (x);					      \
+      ({ uint64_t __w, __x = (x);					      \
 	 if (__builtin_constant_p (x))					      \
 	   __w = __bswap_constant_64 (__x);				      \
 	 else {								      \
-	   unsigned long __tmp = (unsigned long) (__x);                       \
+	   uint64_t __tmp = (uint64_t) (__x);				      \
 	   __asm__ __volatile__ (                                             \
 	      "lrvg  %0,%1"                                                   \
 	      : "=&d" (__w) : "m" (__tmp));                                   \
@@ -105,8 +105,8 @@ __bswap_32 (unsigned int __bsx)
 # else
 #  define __bswap_64(x) \
      __extension__					\
-       ({ union { unsigned long long int __ll;		\
-		  unsigned long int __l[2]; } __w, __r;	\
+       ({ union { uint64_t __ll;			\
+		  uint32_t __l[2]; } __w, __r;		\
 	  __w.__ll = (x);				\
 	  __r.__l[0] = __bswap_32 (__w.__l[1]);		\
 	  __r.__l[1] = __bswap_32 (__w.__l[0]);		\
@@ -123,8 +123,8 @@ __bswap_32 (unsigned int __bsx)
       | (((x) & 0x000000000000ff00ull) << 40)				      \
       | (((x) & 0x00000000000000ffull) << 56))
 
-static __inline unsigned long long int
-__bswap_64 (unsigned long long int __bsx)
+static __inline uint64_t
+__bswap_64 (uint64_t __bsx)
 {
   return __bswap_constant_64 (__bsx);
 }
--- libc/sysdeps/x86/bits/byteswap-16.h.mp	2012-08-19 16:34:46.892008679 +0200
+++ libc/sysdeps/x86/bits/byteswap-16.h	2012-08-22 19:52:49.429954305 +0200
@@ -24,7 +24,7 @@
 # if __GNUC__ >= 2
 #  define __bswap_16(x) \
      (__extension__							      \
-      ({ register unsigned short int __v, __x = (unsigned short int) (x);     \
+      ({ register uint16_t __v, __x = (uint16_t) (x);			      \
 	 if (__builtin_constant_p (__x))				      \
 	   __v = __bswap_constant_16 (__x);				      \
 	 else								      \
@@ -37,12 +37,12 @@
 /* This is better than nothing.  */
 #  define __bswap_16(x) \
      (__extension__							      \
-      ({ register unsigned short int __x = (unsigned short int) (x);	      \
+      ({ register uint16_t __x = (uint16_t) (x);			      \
 	 __bswap_constant_16 (__x); }))
 # endif
 #else
-static __inline unsigned short int
-__bswap_16 (unsigned short int __bsx)
+static __inline uint16_t
+__bswap_16 (uint16_t __bsx)
 {
   return __bswap_constant_16 (__bsx);
 }
--- libc/sysdeps/x86/bits/byteswap.h.mp	2012-08-19 15:32:48.711742439 +0200
+++ libc/sysdeps/x86/bits/byteswap.h	2012-08-22 19:52:49.437954331 +0200
@@ -1,5 +1,5 @@
 /* Macros to swap the order of bytes in integer values.
-   Copyright (C) 1997-2012   Free Software Foundation, Inc.
+   Copyright (C) 1997-2012 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
@@ -28,7 +28,7 @@
 
 /* Swap bytes in 16 bit value.  */
 #define __bswap_constant_16(x) \
-     ((unsigned short int) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
+     ((uint16_t) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
 
 /* Get __bswap_16.  */
 #include <bits/byteswap-16.h>
@@ -40,8 +40,8 @@
 
 #ifdef __GNUC__
 # if __GNUC_PREREQ (4, 2)
-static __inline unsigned int
-__bswap_32 (unsigned int __bsx)
+static __inline uint32_t
+__bswap_32 (uint32_t __bsx)
 {
   return __builtin_bswap32 (__bsx);
 }
@@ -56,7 +56,7 @@ __bswap_32 (unsigned int __bsx)
    `bswap' opcode.  On i386 we have to use three instructions.  */
 #   define __bswap_32(x) \
       (__extension__							      \
-       ({ register unsigned int __v, __x = (x);				      \
+       ({ register uint32_t __v, __x = (x);				      \
 	  if (__builtin_constant_p (__x))				      \
 	    __v = __bswap_constant_32 (__x);				      \
 	  else								      \
@@ -65,7 +65,7 @@ __bswap_32 (unsigned int __bsx)
 #  else
 #   define __bswap_32(x)						      \
       (__extension__							      \
-       ({ register unsigned int __v, __x = (x);				      \
+       ({ register uint32_t __v, __x = (x);				      \
 	  if (__builtin_constant_p (__x))				      \
 	    __v = __bswap_constant_32 (__x);				      \
 	  else								      \
@@ -80,11 +80,11 @@ __bswap_32 (unsigned int __bsx)
 # else
 #  define __bswap_32(x) \
      (__extension__							      \
-      ({ register unsigned int __x = (x); __bswap_constant_32 (__x); }))
+      ({ register uint32_t __x = (x); __bswap_constant_32 (__x); }))
 # endif
 #else
-static __inline unsigned int
-__bswap_32 (unsigned int __bsx)
+static __inline uint32_t
+__bswap_32 (uint32_t __bsx)
 {
   return __bswap_constant_32 (__bsx);
 }
@@ -104,15 +104,15 @@ __bswap_32 (unsigned int __bsx)
 		     | (((x) & 0x00000000000000ffull) << 56)))
 
 # if __GNUC_PREREQ (4, 2)
-static __inline unsigned long long int
-__bswap_64 (unsigned long long int __bsx)
+static __inline uint64_t
+__bswap_64 (uint64_t __bsx)
 {
   return __builtin_bswap64 (__bsx);
 }
 # elif __WORDSIZE == 64
 #  define __bswap_64(x) \
      (__extension__							      \
-      ({ register unsigned long __v, __x = (x);				      \
+      ({ register uint64_t __v, __x = (x);				      \
 	 if (__builtin_constant_p (__x))				      \
 	   __v = __bswap_constant_64 (__x);				      \
 	 else								      \
@@ -121,8 +121,8 @@ __bswap_64 (unsigned long long int __bsx
 # else
 #  define __bswap_64(x) \
      (__extension__                                                           \
-      ({ union { __extension__ unsigned long long int __ll;                   \
-		 unsigned int __l[2]; } __w, __r;                             \
+      ({ union { __extension__ uint64_t __ll;				      \
+		 uint32_t __l[2]; } __w, __r;				      \
 	 if (__builtin_constant_p (x))                                        \
 	   __r.__ll = __bswap_constant_64 (x);                                \
 	 else                                                                 \
@@ -144,8 +144,8 @@ __bswap_64 (unsigned long long int __bsx
       | (((x) & 0x000000000000ff00ull) << 40)				      \
       | (((x) & 0x00000000000000ffull) << 56))
 
-static __inline unsigned long long int
-__bswap_64 (unsigned long long int __bsx)
+static __inline uint64_t
+__bswap_64 (uint64_t __bsx)
 {
   return __bswap_constant_64 (__bsx);
 }
--- libc/sysdeps/generic/stdint.h.mp	2012-08-22 21:00:46.203062052 +0200
+++ libc/sysdeps/generic/stdint.h	2012-08-22 21:04:55.463896478 +0200
@@ -283,7 +283,8 @@ typedef unsigned long long int	uintmax_t
 
 /* The ISO C99 standard specifies that in C++ implementations these
    should only be defined if explicitly requested.  */
-#if !defined __cplusplus || defined __STDC_CONSTANT_MACROS
+#if (!defined __cplusplus || defined __STDC_CONSTANT_MACROS) \
+     && !defined _ISOMAC
 
 /* Signed.  */
 # define INT8_C(c)	c

	Marek

Re: [PATCH] Fix up bswap_* types

[Joseph S. Myers]

On Wed, 22 Aug 2012, Marek Polacek wrote:

> because {,w}ctype.h contains <endian.h> and
> we end up including sysdeps/generic/stdint.h which defines macros above.
> I've circumvent that by using #ifndef _ISOMAC guard around them.

That sounds wrong.  _ISOMAC guards are appropriate in the *internal* 
include/ headers, but the installed headers must conform to the ISO C 
requirements without any such special macros being defined - which means 
not exporting stdint.h symbols in C90 mode.

-- 
Joseph S. Myers
joseph@codesourcery.com

Re: [PATCH] Fix up bswap_* types

[Roland McGrath]

> because {,w}ctype.h contains <endian.h> and
> we end up including sysdeps/generic/stdint.h which defines macros above.
> I've circumvent that by using #ifndef _ISOMAC guard around them.

They are wrong to include <endian.h>, which declares public symbols.
They should use only <bits/endian.h> instead.  This means all the various
bits/endian.h files need their #ifndef _ENDIAN_H sanity checks adjusted.


Thanks,
Roland

Re: [PATCH] Fix up bswap_* types

[Marek Polacek]

On Wed, Aug 22, 2012 at 08:08:38PM +0000, Joseph S. Myers wrote:
> That sounds wrong.  _ISOMAC guards are appropriate in the *internal* 
> include/ headers, but the installed headers must conform to the ISO C 
> requirements without any such special macros being defined - which means 
> not exporting stdint.h symbols in C90 mode.

Aha, haven't noticed.  I'm going to try another approach then...
Thanks,

	Marek

Re: [PATCH] Fix up bswap_* types

[Marek Polacek]

On Wed, Aug 22, 2012 at 01:12:24PM -0700, Roland McGrath wrote:
> They are wrong to include <endian.h>, which declares public symbols.
> They should use only <bits/endian.h> instead.  This means all the various
> bits/endian.h files need their #ifndef _ENDIAN_H sanity checks adjusted.

In that case I think I could in {w,}ctype.h before including
<bits/endian.h> define say `__need_byteorder' and then tweak guards
in all the bits/endian.h so that they look like

#if !defined _ENDIAN_H && !defined __need_byteorder
 # error blah...
#endif

And it also looks that I have to move following definitions:
#define __LITTLE_ENDIAN 1234
#define __BIG_ENDIAN    4321
#define __PDP_ENDIAN    3412
from string/endian.h to ctype/ctype.h, otherwise charset test
when running check just blow up.

What do ya say?

	Marek

Re: [PATCH] Fix up bswap_* types

[Roland McGrath]

> In that case I think I could in {w,}ctype.h before including
> <bits/endian.h> define say `__need_byteorder' and then tweak guards
> in all the bits/endian.h so that they look like
> 
> #if !defined _ENDIAN_H && !defined __need_byteorder
>  # error blah...
> #endif
> 
> And it also looks that I have to move following definitions:
> #define __LITTLE_ENDIAN 1234
> #define __BIG_ENDIAN    4321
> #define __PDP_ENDIAN    3412
> from string/endian.h to ctype/ctype.h, otherwise charset test
> when running check just blow up.
> 
> What do ya say?

Oh, yeah.  So I think what you actually want in ctype.h et al is:

	#define __need_byteorder
	#include <endian.h>

Then make <endian.h> just define __*_ENDIAN and include <bits/endian.h>
if included with __need_byteorder defined, and only do its other
declarations (and _ENDIAN_H) if included without __need_byteorder defined.


Thanks,
Roland

Re: [PATCH] Fix up bswap_* types

[Joseph S. Myers]

On Thu, 23 Aug 2012, Marek Polacek wrote:

> On Wed, Aug 22, 2012 at 01:12:24PM -0700, Roland McGrath wrote:
> > They are wrong to include <endian.h>, which declares public symbols.
> > They should use only <bits/endian.h> instead.  This means all the various
> > bits/endian.h files need their #ifndef _ENDIAN_H sanity checks adjusted.
> 
> In that case I think I could in {w,}ctype.h before including
> <bits/endian.h> define say `__need_byteorder' and then tweak guards
> in all the bits/endian.h so that they look like

Personally I find the __need_* scheme pretty fragile, and it's also been 
reported as causing problems for such things as attempts at pre-parsed 
headers in GCC - it's generally nicer if a header does something 
well-defined that doesn't depend on whether such a macro is defined before 
including it.

Thus, whenever you are tempted to give a header a special __need_* 
interface, I'd rather split out the relevant bits into a new internal 
(bits/*) header and include that header in both places.

-- 
Joseph S. Myers
joseph@codesourcery.com

Re: [PATCH] Fix up bswap_* types

[Roland McGrath]

> Personally I find the __need_* scheme pretty fragile, and it's also been 
> reported as causing problems for such things as attempts at pre-parsed 
> headers in GCC - it's generally nicer if a header does something 
> well-defined that doesn't depend on whether such a macro is defined before 
> including it.

It's true.  I was suggesting something that follows the prevailing scheme
for such cases, but that doesn't mean it's the ideal scheme.

> Thus, whenever you are tempted to give a header a special __need_* 
> interface, I'd rather split out the relevant bits into a new internal 
> (bits/*) header and include that header in both places.

Yes, we could instead move __*_ENDIAN into another file.  The cleanest
arrangement would be:

* bits/endian.h becomes a generic header that defines __*_ENDIAN and does
  #include <bits/byteorder.h>.  Only this file would need complex
  guards to allow inclusion via <endian.h> or <ctype.h> or <wctype.h>.
* sysdeps bits/endian.h files all renamed to bits/byteorder.h and have
  a guard for _BITS_BYTEORDER_H.


Thanks,
Roland

Re: [PATCH] Fix up bswap_* types

[Marek Polacek]

On Wed, Aug 22, 2012 at 04:46:10PM -0700, Roland McGrath wrote:
> Yes, we could instead move __*_ENDIAN into another file.  The cleanest
> arrangement would be:
> 
> * bits/endian.h becomes a generic header that defines __*_ENDIAN and does
>   #include <bits/byteorder.h>.  Only this file would need complex
>   guards to allow inclusion via <endian.h> or <ctype.h> or <wctype.h>.
> * sysdeps bits/endian.h files all renamed to bits/byteorder.h and have
>   a guard for _BITS_BYTEORDER_H.

That sounds good, thank both of you.  I'll try hack something up 
over the next few days.

	Marek