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AC_PROTOTYPE(function, includes, code, TAG1, values1 [, TAG2, values2 [...]])
1.1.1.1 (2001/07/26) Miscellaneous @ ac-archive-0.5.39
Loic Dachary <loic@senga.org>
Try all the combinations of <TAG1>, <TAG2>... to successfully compile <code>. <TAG1>, <TAG2>, ... are substituted in <code> and <include> with values found in <values1>, <values2>, ... respectively. <values1>, <values2>, ... contain a list of possible values for each corresponding tag and all combinations are tested. When AC_TRY_COMPILE(include, code) is successfull for a given substitution, the macro stops and defines the following macros: FUNCTION_TAG1, FUNCTION_TAG2, ... using AC_DEFINE() with values set to the current values of <TAG1>, <TAG2>, ... If no combination is successfull the configure script is aborted with a message.
Intended purpose is to find which combination of argument types is acceptable for a given function <function>. It is recommended to list the most specific types first. For instance ARG1, [size_t, int] instead of ARG1, [int, size_t].
Generic usage pattern:
1) add a call in configure.in
AC_PROTOTYPE(...)
2) call autoheader to see which symbols are not covered
3) add the lines in acconfig.h
/* Type of Nth argument of function */
#undef FUNCTION_ARGN
4) Within the code use FUNCTION_ARGN instead of an hardwired type
Complete example:
1) configure.in
AC_PROTOTYPE(getpeername,
[
#include <sys/types.h>
#include <sys/socket.h>
],
[
int a = 0;
ARG2 * b = 0;
ARG3 * c = 0;
getpeername(a, b, c);
],
ARG2, [struct sockaddr, void],
ARG3, [socklen_t, size_t, int, unsigned int, long unsigned int])
2) call autoheader
autoheader: Symbol `GETPEERNAME_ARG2' is not covered by ./acconfig.h
autoheader: Symbol `GETPEERNAME_ARG3' is not covered by ./acconfig.h
3) acconfig.h
/* Type of second argument of getpeername */
#undef GETPEERNAME_ARG2
/* Type of third argument of getpeername */
#undef GETPEERNAME_ARG3
4) in the code
...
GETPEERNAME_ARG2 name;
GETPEERNAME_ARG3 namelen;
...
ret = getpeername(socket, &name, &namelen);
...
Implementation notes: generating all possible permutations of the arguments is not easily done with the usual mixture of shell and m4, that is why this macro is almost 100% m4 code. It generates long but simple to read code.
AC_DEFUN([AC_PROTOTYPE],[ dnl dnl Upper case function name dnl pushdef([function],translit([$1], [a-z], [A-Z])) dnl dnl Collect tags that will be substituted dnl pushdef([tags],[AC_PROTOTYPE_TAGS(builtin([shift],builtin([shift],builtin([shift],$@))))]) dnl dnl Wrap in a 1 time loop, when a combination is found break to stop the combinatory exploration dnl for i in 1 do AC_PROTOTYPE_LOOP(AC_PROTOTYPE_REVERSE($1, AC_PROTOTYPE_SUBST($2,tags),AC_PROTOTYPE_SUBST($3,tags),builtin([shift],builtin([shift],builtin([shift],$@))))) AC_MSG_ERROR($1 unable to find a working combination) done popdef([tags]) popdef([function]) ]) dnl dnl AC_PROTOTYPE_REVERSE(list) dnl dnl Reverse the order of the <list> dnl AC_DEFUN([AC_PROTOTYPE_REVERSE],[ifelse($#,0,,$#,1,[[$1]],[AC_PROTOTYPE_REVERSE(builtin([shift],$@)),[$1]])]) dnl dnl AC_PROTOTYPE_SUBST(string, tag) dnl dnl Substitute all occurence of <tag> in <string> with <tag>_VAL. dnl Assumes that tag_VAL is a macro containing the value associated to tag. dnl AC_DEFUN([AC_PROTOTYPE_SUBST],[ifelse($2,,[$1],[AC_PROTOTYPE_SUBST(patsubst([$1],[$2],[$2[]_VAL]),builtin([shift],builtin([shift],$@)))])]) dnl dnl AC_PROTOTYPE_TAGS([tag, values, [tag, values ...]]) dnl dnl Generate a list of <tag> by skipping <values>. dnl AC_DEFUN([AC_PROTOTYPE_TAGS],[ifelse($1,,[],[$1, AC_PROTOTYPE_TAGS(builtin([shift],builtin([shift],$@)))])]) dnl dnl AC_PROTOTYPE_DEFINES(tags) dnl dnl Generate a AC_DEFINE(function_tag, tag_VAL) for each tag in <tags> list dnl Assumes that function is a macro containing the name of the function in upper case dnl and that tag_VAL is a macro containing the value associated to tag. dnl AC_DEFUN([AC_PROTOTYPE_DEFINES],[ifelse($1,,[],[AC_DEFINE(function[]_$1, $1_VAL) AC_PROTOTYPE_DEFINES(builtin([shift],$@))])]) dnl dnl AC_PROTOTYPE_STATUS(tags) dnl dnl Generates a message suitable for argument to AC_MSG_* macros. For each tag dnl in the <tags> list the message tag => tag_VAL is generated. dnl Assumes that tag_VAL is a macro containing the value associated to tag. dnl AC_DEFUN([AC_PROTOTYPE_STATUS],[ifelse($1,,[],[$1 => $1_VAL AC_PROTOTYPE_STATUS(builtin([shift],$@))])]) dnl dnl AC_PROTOTYPE_EACH(tag, values) dnl dnl Call AC_PROTOTYPE_LOOP for each values and define the macro tag_VAL to dnl the current value. dnl AC_DEFUN([AC_PROTOTYPE_EACH],[ ifelse($2,, [ ], [ pushdef([$1_VAL], $2) AC_PROTOTYPE_LOOP(rest) popdef([$1_VAL]) AC_PROTOTYPE_EACH($1, builtin([shift], builtin([shift], $@))) ]) ]) dnl dnl AC_PROTOTYPE_LOOP([tag, values, [tag, values ...]], code, include, function) dnl dnl If there is a tag/values pair, call AC_PROTOTYPE_EACH with it. dnl If there is no tag/values pair left, tries to compile the code and include dnl using AC_TRY_COMPILE. If it compiles, AC_DEFINE all the tags to their dnl current value and exit with success. dnl AC_DEFUN([AC_PROTOTYPE_LOOP],[ ifelse(builtin([eval], $# > 3), 1, [ pushdef([rest],[builtin([shift],builtin([shift],$@))]) AC_PROTOTYPE_EACH($2,$1) popdef([rest]) ], [ AC_MSG_CHECKING($3 AC_PROTOTYPE_STATUS(tags)) dnl dnl Activate fatal warnings if possible, gives better guess dnl ac_save_CPPFLAGS="$CPPFLAGS" ifelse(AC_LANG,CPLUSPLUS,if test "$GXX" = "yes" ; then CPPFLAGS="$CPPFLAGS -Werror" ; fi) ifelse(AC_LANG,C,if test "$GCC" = "yes" ; then CPPFLAGS="$CPPFLAGS -Werror" ; fi) AC_TRY_COMPILE($2, $1, [ CPPFLAGS="$ac_save_CPPFLAGS" AC_MSG_RESULT(ok) AC_PROTOTYPE_DEFINES(tags) break; ], [ CPPFLAGS="$ac_save_CPPFLAGS" AC_MSG_RESULT(not ok) ]) ] ) ])