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* acgeneral.m4 (AC_CHECK_TYPE_INTERNAL): Use the scheme proposed
by Alexandre Oliva for testing the definition of TYPE: TYPE *foo; sizeof (TYPE);
This commit is contained in:
Akim Demaille
parent
6bc62513f5
commit
635d167e35
@ -1,3 +1,10 @@
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2000-02-07 Akim Demaille <akim@epita.fr>
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* acgeneral.m4 (AC_CHECK_TYPE_INTERNAL): Use the scheme proposed
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by Alexandre Oliva for testing the definition of TYPE:
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TYPE *foo;
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sizeof (TYPE);
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2000-02-07 Akim Demaille <akim@epita.fr>
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* acspecific.m4 (AC_C_CONST): Don't changequote, there is no need
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82
acgeneral.m4
82
acgeneral.m4
@ -3031,26 +3031,78 @@ AC_VAR_POPDEF([ac_Sizeof])dnl
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dnl ### Checking for typedefs
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dnl AC_CHECK_TYPE_INTERNAL(TYPE,
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dnl [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND],
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dnl [INCLUDES])
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dnl ----------------------------------------------------------------
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dnl Check whether the type TYPE is supported by the system, maybe via the
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dnl the provided includes. This macro implements the former task of
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dnl AC_CHECK_TYPE, with one big difference though: AC_CHECK_TYPE was
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dnl grepping in the headers, what led to many problems, BTW, until
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dnl the egrep expression was correct and did not given false positives.
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dnl Now, we try to compile a variable declaration. It is probably slower,
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dnl but it is *much* safer, and in addition, allows to check for types
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dnl defined by the compiler (e.g., unsigned long long), not only for
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dnl typedefs.
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dnl FIXME: This is *the* macro which ought to be named AC_CHECK_TYPE.
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# AC_CHECK_TYPE_INTERNAL(TYPE,
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# [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND],
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# [INCLUDES])
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# ----------------------------------------------------------------
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# Check whether the type TYPE is supported by the system, maybe via the
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# the provided includes. This macro implements the former task of
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# AC_CHECK_TYPE, with one big difference though: AC_CHECK_TYPE was
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# grepping in the headers, which, BTW, led to many problems until
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# the egrep expression was correct and did not given false positives.
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# It turned out there are even portability issues with egrep...
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#
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# The most obvious way to check for a TYPE is just to compile a variable
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# definition:
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#
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# TYPE my_var;
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#
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# Unfortunately this does not work for const qualified types in C++,
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# where you need an initializer. So you think of
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#
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# TYPE my_var = (TYPE) 0;
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#
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# Unfortunately, again, this is not valid for some C++ classes.
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#
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# Then you look for another scheme. For instance you think of declaring
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# a function which uses a parameter of type TYPE:
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#
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# int foo (TYPE param);
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#
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# but of course you soon realize this does not make it with K&R
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# compilers. And by no ways you want to
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#
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# int foo (param)
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# TYPE param
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# { ; }
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#
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# since this time it's C++ who is not happy.
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#
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# Don't even think of the return type of a function, since K&R cries
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# there too. So you start thinking of declaring a *pointer* to this TYPE:
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#
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# TYPE *p;
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#
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# but you know fairly well that this is legal in C for aggregates which
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# are unknown (TYPE = struct does-not-exist).
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#
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# Then you think of using sizeof to make sure the TYPE is really
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# defined:
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#
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# sizeof (TYPE);
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#
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# But this succeeds if TYPE is a variable: you get the size of the
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# variable's type!!!
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#
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# This time you tell yourself the last two options *together* will make
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# it. And indeed this is the solution invented by Alexandre Oliva.
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#
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# Also note that we use
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#
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# if (sizeof (TYPE))
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#
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# to `read' sizeof (to avoid warnings), while not depending on its type
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# (not necessarily size_t etc.).
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#
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# FIXME: This is *the* macro which ought to be named AC_CHECK_TYPE.
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AC_DEFUN(AC_CHECK_TYPE_INTERNAL,
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[AC_REQUIRE([AC_HEADER_STDC])dnl
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AC_VAR_PUSHDEF([ac_Type], [ac_cv_type_$1])dnl
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AC_CACHE_CHECK([for $1], ac_Type,
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[AC_TRY_COMPILE(AC_INCLUDES_DEFAULT([$4]),
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[$1 foo;],
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[$1 *foo;
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if (sizeof ($1))
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return 0;],
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AC_VAR_SET(ac_Type, yes),
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AC_VAR_SET(ac_Type, no))])
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AC_SHELL_IFELSE(test AC_VAR_GET(ac_Type) = yes,
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@ -2693,7 +2693,7 @@ The following macros check for certain structures or structure members.
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@cvindex HAVE_STRUCT_STAT_ST_BLKSIZE
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@cvindex HAVE_ST_BLKSIZE
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If @code{struct stat} contains an @code{st_blksize} member, define
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@code{HAVE_STRUCT STAT_ST_BLKSIZE}. The former name,
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@code{HAVE_STRUCT_STAT_ST_BLKSIZE}. The former name,
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@code{HAVE_ST_BLKSIZE} is to be avoided, as its support will cease in
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the future. This macro is obsoleted, and should be replaced by
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@example
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@ -2897,8 +2897,8 @@ This macro has a broken design. First, although it is a member of the
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@code{CHECK} clan, singular subfamily, it does more than just checking.
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Second, the replacement it performs is done via @samp{#define @var{type}
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@var{default}}, although a @samp{typedef} is expected. Therefore, in
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the future, this macro shall be removed or replaced. User are adviced
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to use @code{AC_CHECK_TYPES} preferably.
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the future, this macro shall be removed or replaced. Users are adviced
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to prefer @code{AC_CHECK_TYPES}.
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@end defmac
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@ -2693,7 +2693,7 @@ The following macros check for certain structures or structure members.
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@cvindex HAVE_STRUCT_STAT_ST_BLKSIZE
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@cvindex HAVE_ST_BLKSIZE
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If @code{struct stat} contains an @code{st_blksize} member, define
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@code{HAVE_STRUCT STAT_ST_BLKSIZE}. The former name,
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@code{HAVE_STRUCT_STAT_ST_BLKSIZE}. The former name,
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@code{HAVE_ST_BLKSIZE} is to be avoided, as its support will cease in
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the future. This macro is obsoleted, and should be replaced by
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@example
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@ -2897,8 +2897,8 @@ This macro has a broken design. First, although it is a member of the
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@code{CHECK} clan, singular subfamily, it does more than just checking.
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Second, the replacement it performs is done via @samp{#define @var{type}
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@var{default}}, although a @samp{typedef} is expected. Therefore, in
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the future, this macro shall be removed or replaced. User are adviced
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to use @code{AC_CHECK_TYPES} preferably.
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the future, this macro shall be removed or replaced. Users are adviced
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to prefer @code{AC_CHECK_TYPES}.
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@end defmac
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@ -3031,26 +3031,78 @@ AC_VAR_POPDEF([ac_Sizeof])dnl
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dnl ### Checking for typedefs
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dnl AC_CHECK_TYPE_INTERNAL(TYPE,
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dnl [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND],
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dnl [INCLUDES])
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dnl ----------------------------------------------------------------
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dnl Check whether the type TYPE is supported by the system, maybe via the
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dnl the provided includes. This macro implements the former task of
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dnl AC_CHECK_TYPE, with one big difference though: AC_CHECK_TYPE was
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dnl grepping in the headers, what led to many problems, BTW, until
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dnl the egrep expression was correct and did not given false positives.
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dnl Now, we try to compile a variable declaration. It is probably slower,
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dnl but it is *much* safer, and in addition, allows to check for types
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dnl defined by the compiler (e.g., unsigned long long), not only for
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dnl typedefs.
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dnl FIXME: This is *the* macro which ought to be named AC_CHECK_TYPE.
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# AC_CHECK_TYPE_INTERNAL(TYPE,
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# [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND],
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# [INCLUDES])
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# ----------------------------------------------------------------
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# Check whether the type TYPE is supported by the system, maybe via the
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# the provided includes. This macro implements the former task of
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# AC_CHECK_TYPE, with one big difference though: AC_CHECK_TYPE was
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# grepping in the headers, which, BTW, led to many problems until
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# the egrep expression was correct and did not given false positives.
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# It turned out there are even portability issues with egrep...
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#
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# The most obvious way to check for a TYPE is just to compile a variable
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# definition:
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#
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# TYPE my_var;
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#
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# Unfortunately this does not work for const qualified types in C++,
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# where you need an initializer. So you think of
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#
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# TYPE my_var = (TYPE) 0;
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#
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# Unfortunately, again, this is not valid for some C++ classes.
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#
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# Then you look for another scheme. For instance you think of declaring
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# a function which uses a parameter of type TYPE:
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#
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# int foo (TYPE param);
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#
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# but of course you soon realize this does not make it with K&R
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# compilers. And by no ways you want to
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#
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# int foo (param)
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# TYPE param
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# { ; }
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#
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# since this time it's C++ who is not happy.
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#
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# Don't even think of the return type of a function, since K&R cries
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# there too. So you start thinking of declaring a *pointer* to this TYPE:
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#
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# TYPE *p;
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#
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# but you know fairly well that this is legal in C for aggregates which
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# are unknown (TYPE = struct does-not-exist).
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#
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# Then you think of using sizeof to make sure the TYPE is really
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# defined:
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#
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# sizeof (TYPE);
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#
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# But this succeeds if TYPE is a variable: you get the size of the
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# variable's type!!!
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#
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# This time you tell yourself the last two options *together* will make
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# it. And indeed this is the solution invented by Alexandre Oliva.
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#
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# Also note that we use
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#
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# if (sizeof (TYPE))
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#
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# to `read' sizeof (to avoid warnings), while not depending on its type
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# (not necessarily size_t etc.).
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#
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# FIXME: This is *the* macro which ought to be named AC_CHECK_TYPE.
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AC_DEFUN(AC_CHECK_TYPE_INTERNAL,
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[AC_REQUIRE([AC_HEADER_STDC])dnl
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AC_VAR_PUSHDEF([ac_Type], [ac_cv_type_$1])dnl
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AC_CACHE_CHECK([for $1], ac_Type,
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[AC_TRY_COMPILE(AC_INCLUDES_DEFAULT([$4]),
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[$1 foo;],
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[$1 *foo;
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if (sizeof ($1))
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return 0;],
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AC_VAR_SET(ac_Type, yes),
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AC_VAR_SET(ac_Type, no))])
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AC_SHELL_IFELSE(test AC_VAR_GET(ac_Type) = yes,
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