Mercurial > gnulib
changeset 27308:07b3f42def3c
* m4/flexmember.m4 (AC_C_FLEXIBLE_ARRAY_MEMBER):
Mention that offsetof should be used instead of sizeof.
From Bruno Haible.
| author | Paul Eggert <eggert@cs.ucla.edu> |
|---|---|
| date | Tue, 07 Nov 2006 17:20:07 +0000 |
| parents | f68806b63db7 |
| children | 43a11ebbec31 |
| files | ChangeLog m4/flexmember.m4 |
| diffstat | 2 files changed, 11 insertions(+), 1 deletions(-) [+] |
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--- a/ChangeLog Tue Nov 07 14:57:19 2006 +0000 +++ b/ChangeLog Tue Nov 07 17:20:07 2006 +0000 @@ -1,3 +1,9 @@ +2006-11-07 Paul Eggert <eggert@cs.ucla.edu> + + * m4/flexmember.m4 (AC_C_FLEXIBLE_ARRAY_MEMBER): + Mention that offsetof should be used instead of sizeof. + From Bruno Haible. + 2006-11-07 Bruno Haible <bruno@clisp.org> * lib/w32spawn.h (prepare_spawn): Use XNMALLOC instead of xmalloc.
--- a/m4/flexmember.m4 Tue Nov 07 14:57:19 2006 +0000 +++ b/m4/flexmember.m4 Tue Nov 07 17:20:07 2006 +0000 @@ -41,7 +41,11 @@ [Define to nothing if C supports flexible array members, and to 1 if it does not. That way, with a declaration like `struct s { int n; double d@<:@FLEXIBLE_ARRAY_MEMBER@:>@; };', the struct hack - can be used with pre-C99 compilers.]) + can be used with pre-C99 compilers. + When computing the size of such an object, don't use 'sizeof (struct s)' + as it overestimates the size. Use 'offsetof (struct s, d)' instead. + Don't use 'offsetof (struct s, d@<:@0@:>@)', as this doesn't work with + MSVC and with C++ compilers.]) else AC_DEFINE([FLEXIBLE_ARRAY_MEMBER], 1) fi