AC_CHECK_TYPE, AC_CHECK_TYPES.
* doc/autoconf.texi (Generic types): C types must be type-names
(the C terminology), not type-ids (the C++ term). C++ types
must not be anonymous.
* lib/autoconf/types.m4 (_AC_CHECK_TYPE_NEW): Remove special case
for C++; this drops support for anonymous struct and union types,
which were problematic anyway.
* tests/semantics.at (AC_CHECK_HEADERS_NEW): Adjust test to work even
for C++.
+2007-04-12 Paul Eggert <eggert@cs.ucla.edu>
+
+ * NEWS: Document recent changes to AC_CHECK_ALIGNOF, AC_CHECK_SIZEOF,
+ AC_CHECK_TYPE, AC_CHECK_TYPES.
+ * doc/autoconf.texi (Generic types): C types must be type-names
+ (the C terminology), not type-ids (the C++ term). C++ types
+ must not be anonymous.
+ * lib/autoconf/types.m4 (_AC_CHECK_TYPE_NEW): Remove special case
+ for C++; this drops support for anonymous struct and union types,
+ which were problematic anyway.
+ * tests/semantics.at (AC_CHECK_HEADERS_NEW): Adjust test to work even
+ for C++.
+
2007-04-12 Jim Meyering <jim@meyering.net>
* doc/autoconf.texi (Libraries): Typo fix: insert missing "in".
** AC_C_BIGENDIAN now supports universal binaries a la Mac OS X.
+** AC_CHECK_ALIGNOF's type argument T is now documented better: it must
+ be a string of tokens such that "T y;" is a valid member declaration
+ in a struct.
+
+** AC_CHECK_SIZEOF now accepts objects as well as types: the general rule
+ is that sizeof (X) works, then AC_CHECK_SIZEOF (X) should work.
+
+** AC_CHECK_TYPE and AC_CHECK_TYPES now work on any C type-name; formerly,
+ they did not work for function types. In C++, they now work on any
+ type-id that can be the operand of sizeof; this is similar to C,
+ except it excludes anonymous struct and union types. Formerly,
+ some (but not all) C++ types involving anonymous struct and union
+ were accepted, though this was not documented.
+
** Autoconf now requires GNU M4 1.4.5 or later. Earlier versions of M4 have
a bug in macro tracing that interferes with the interaction between
Autoconf and Automake. GNU M4 1.4.8 or later is recommended.
Check whether @var{type} is defined. It may be a compiler builtin type
or defined by the @var{includes} (@pxref{Default Includes}).
-In C, @var{type} must be a type-id, so that the expression @samp{sizeof
+In C, @var{type} must be a type-name, so that the expression @samp{sizeof
(@var{type})} is valid (but @samp{sizeof ((@var{type}))} is not). The
-rules in C++ are currently more complicated and restrictive: @var{type}
-must be a string of tokens such that @samp{typedef @var{type} foo;} is a
-valid type definition. However, the C++ approach has problems (for
-example, it mishandles function types) and may change in future versions
-of Autoconf.
+same test is applied when compiling for C++, which means that in C++
+@var{type} should be a type-id and should not be an anonymous
+@samp{struct} or @samp{union}.
@end defmac
@defmac AC_CHECK_ALIGNOF (@var{type}, @dvar{includes, default-includes})
@acindex{CHECK_ALIGNOF}
Define @code{ALIGNOF_@var{type}} (@pxref{Standard Symbols}) to be the
-alignment in bytes of @var{type}. @samp{@var{type} x;} must be valid as
+alignment in bytes of @var{type}. @samp{@var{type} y;} must be valid as
a structure member declaration. If @samp{type} is unknown, the result
is 0. If no @var{includes} are specified, the default includes are used
(@pxref{Default Includes}).
# if (sizeof (TYPE))
#
# to `read' sizeof (to avoid warnings), while not depending on its type
-# (not necessarily size_t etc.). Equally, instead of defining an unused
-# variable, we just use a cast to avoid warnings from the compiler.
-#
-# Now, the next issue is that C++ disallows defining types inside casts
-# and inside `sizeof()', but we would like to allow unnamed structs, for
-# use inside AC_CHECK_SIZEOF, for example. So for C++ we create a typedef
-# of the new type. Note that this breaks for some types, e.g., function
-# types, but we don't know C++ well enough to fix this.
+# (not necessarily size_t etc.).
+#
+# C++ disallows defining types inside `sizeof ()', but that's OK,
+# since we don't want to consider unnamed structs to be types for C++,
+# precisely because they don't work in cases like that.
m4_define([_AC_CHECK_TYPE_NEW],
[AS_VAR_PUSHDEF([ac_Type], [ac_cv_type_$1])dnl
AC_CACHE_CHECK([for $1], [ac_Type],
[AS_VAR_SET([ac_Type], [no])
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT([$4])
-#ifdef __cplusplus
-typedef $1 ac__type_new_;
-#endif
-],
-[#ifdef __cplusplus
-if ((ac__type_new_ *) 0)
- return 0;
-if (sizeof (ac__type_new_))
- return 0;
-#else
-if (sizeof ($1))
- return 0;
-#endif
-])],
+AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT([$4])],
+ [if (sizeof ($1))
+ return 0;])],
[AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT([$4])],
[if (sizeof (($1)))
# ----------------------
AT_CHECK_MACRO_CROSS([AC_CHECK_SIZEOF struct],
[[AC_C_CONST
-AC_CHECK_SIZEOF([struct { char c; int x; }])
-AC_CHECK_SIZEOF([const struct { const char *p; int x; }])
+AC_CHECK_SIZEOF([struct x], [], [struct x { char c; int x; };])
+AC_CHECK_SIZEOF([const struct x], [], [struct x { const char *p; int x; };])
AC_CHECK_SIZEOF([struct nosuchstruct])
]],
-[AT_CHECK([[grep "#define SIZEOF_STRUCT___CHAR_C__INT_X___ [^0]" config.h]],
+[AT_CHECK([[grep "#define SIZEOF_STRUCT_X [^0]" config.h]],
0, ignore)
-AT_CHECK([[grep "#define SIZEOF_CONST_STRUCT___CONST_CHAR_PP__INT_X___ [^0]" config.h]],
+AT_CHECK([[grep "#define SIZEOF_CONST_STRUCT_X [^0]" config.h]],
0, ignore)
AT_CHECK([[grep "#define SIZEOF_STRUCT_NOSUCHSTRUCT 0" config.h]],
0, ignore)
projects / thirdparty / autoconf.git / commitdiff
