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Re: new module alignof
From: |
Bruno Haible |
Subject: |
Re: new module alignof |
Date: |
Sun, 31 May 2009 21:46:26 +0200 |
User-agent: |
KMail/1.9.9 |
Eric Blake wrote:
> So if I understand correctly, you are trading one set of portability
> problems (the AIX workaround guesses wrong for char and short) for another
> (alignof() must not be used to initialize an enumerator, but can be used
> in all other contexts). Shouldn't this at least be documented in the
> alignof.h header?
Good point. Yes:
2009-05-31 Bruno Haible <address@hidden>
* lib/alignof.h (alignof_slot, alignof_type, alignof): Document
restriction due to compiler bugs.
Reported by Eric Blake.
--- lib/alignof.h.orig 2009-05-31 21:44:52.000000000 +0200
+++ lib/alignof.h 2009-05-31 21:44:22.000000000 +0200
@@ -21,7 +21,9 @@
#include <stddef.h>
/* Determine the alignment of a structure slot (field) of a given type,
- at compile time. Note that the result depends on the ABI. */
+ at compile time. Note that the result depends on the ABI.
+ Note: The result cannot be used as a value for an 'enum' constant,
+ due to bugs in HP-UX 10.20 cc and AIX 3.2.5 xlc. */
#if defined __cplusplus
template <class type> struct alignof_helper { char __slot1; type __slot2; };
# define alignof_slot(type) offsetof (alignof_helper<type>, __slot2)
@@ -33,7 +35,9 @@
Note that this is not necessarily the same as alignof_slot(type).
For example, with GNU C on x86 platforms: alignof_type(double) = 8, but
- when -malign-double is not specified: alignof_slot(double) = 4,
- - when -malign-double is specified: alignof_slot(double) = 8. */
+ - when -malign-double is specified: alignof_slot(double) = 8.
+ Note: The result cannot be used as a value for an 'enum' constant,
+ due to bugs in HP-UX 10.20 cc and AIX 3.2.5 xlc. */
#if defined __GNUC__
# define alignof_type __alignof__
#else
@@ -42,7 +46,8 @@
/* alignof is an alias for alignof_slot semantics, since that's what most
callers need.
- Note: The result cannot be used as a value for an 'enum' constant, */
+ Note: The result cannot be used as a value for an 'enum' constant,
+ due to bugs in HP-UX 10.20 cc and AIX 3.2.5 xlc. */
#define alignof alignof_slot
#endif /* _ALIGNOF_H */
- Re: sys_socket: sockaddr_storage, new module alignof, (continued)
- Re: sys_socket: sockaddr_storage, new module alignof, Simon Josefsson, 2009/05/08
- Re: sys_socket: sockaddr_storage, new module alignof, Bruno Haible, 2009/05/08
- Re: sys_socket: sockaddr_storage, new module alignof, Simon Josefsson, 2009/05/08
- Re: sys_socket: sockaddr_storage, new module alignof, Simon Josefsson, 2009/05/08
- Re: sys_socket: sockaddr_storage, new module alignof, Bruno Haible, 2009/05/08
- Re: sys_socket: sockaddr_storage, new module alignof, Simon Josefsson, 2009/05/10
- Re: sys_socket: sockaddr_storage, new module alignof, Simon Josefsson, 2009/05/08
- Re: sys_socket: sockaddr_storage, new module alignof, Simon Josefsson, 2009/05/08
- Re: sys_socket: sockaddr_storage, new module alignof, Bruno Haible, 2009/05/12
- Re: sys_socket: sockaddr_storage, new module alignof, Eric Blake, 2009/05/12
- Re: new module alignof,
Bruno Haible <=
- Re: sys_socket: sockaddr_storage, new module alignof, Eric Blake, 2009/05/12
- Re: new module alignof, Bruno Haible, 2009/05/31