* Writing Test Programs:: Forging source files for compilers
* Running the Preprocessor:: Detecting preprocessor symbols
* Running the Compiler:: Detecting language or header features
-* Examining Libraries:: Detecting functions and global variables
+* Running the Linker:: Detecting library features
* Run Time:: Testing for run-time features
* Systemology:: A zoology of operating systems
* Multiple Cases:: Tests for several possible values
* Writing Test Programs:: Forging source files for compilers
* Running the Preprocessor:: Detecting preprocessor symbols
* Running the Compiler:: Detecting language or header features
-* Examining Libraries:: Detecting functions and global variables
+* Running the Linker:: Detecting library features
* Run Time:: Testing for run-time features
* Systemology:: A zoology of operating systems
* Multiple Cases:: Tests for several possible values
@}
@end example
+
+@defmac AC_LANG_CALL (@var{prologue}, @var{function})
+@acindex LANG_CALL
+Expands into a source file which consists of the @var{prologue}, and
+then a call to the @var{function} as body of the main function (e.g.,
+@code{main} in C). Since it uses @code{AC_LANG_PROGRAMS}, the feature
+of the latter are available.
+
+This function will probably be replaced in the feature by a version
+which would enable specifying the arguments. The use of this macro is
+not encouraged, as it violates strongly the typing system.
+@end defmac
+
+
+@defmac AC_LANG_FUNC_LINK_TRY (@var{prologue}, @var{function})
+@acindex LANG_FUNC_LINK_TRY
+Expands into a source file which consists of the @var{prologue}, and
+then a pseudo use of the @var{function} as body of the main function
+(e.g., @code{main} in C): a simple (function pointer) assignment. Since
+it uses @code{AC_LANG_PROGRAMS}, the feature of the latter are
+available.
+
+As @code{AC_LANG_CALL}, this macro is documented only for completeness.
+It is considered to be severely broken, and in the future will be
+removed in favor of actual function calls (with properly typed
+arguments).
+@end defmac
+
@node Running the Preprocessor
@section Running the Preprocessor
@code{FFLAGS} will be used when compiling.
This macro does not try to link; use @code{AC_LINK_IFELSE} if you need
-to do that (@pxref{Examining Libraries}).
+to do that (@pxref{Running the Linker}).
@end defmac
-@node Examining Libraries
-@section Examining Libraries
+@node Running the Linker
+@section Running the Linker
To check for a library, a function, or a global variable, Autoconf
@command{configure} scripts try to compile and link a small program that
-uses it. This is unlike Metaconfig, which by default uses @code{nm}
-or @code{ar} on the C library to try to figure out which functions are
+uses it. This is unlike Metaconfig, which by default uses @code{nm} or
+@code{ar} on the C library to try to figure out which functions are
available. Trying to link with the function is usually a more reliable
approach because it avoids dealing with the variations in the options
and output formats of @code{nm} and @code{ar} and in the location of the
standard libraries. It also allows configuring for cross-compilation or
-checking a function's run-time behavior if needed. On the other hand, it
-can be slower than scanning the libraries once.
-
-A few systems have linkers that do not return a failure exit status when
-there are unresolved functions in the link. This bug makes the
-configuration scripts produced by Autoconf unusable on those systems.
-However, some of them can be given options that make the exit status
-correct. This is a problem that Autoconf does not currently handle
-automatically. If users encounter this problem, they might be able to
-solve it by setting @code{LDFLAGS} in the environment to pass whatever
-options the linker needs (for example, @option{-Wl,-dn} on @sc{mips
-risc/os}).
-
-@code{AC_TRY_LINK} is used to compile test programs to test for
+checking a function's run-time behavior if needed. On the other hand,
+it can be slower than scanning the libraries once, but accuracy is more
+important than speed.
+
+@c FIXME: Errr.... I doubt this matters today... --akim, 2002.
+@c A few systems have linkers that do not return a failure exit status when
+@c there are unresolved functions in the link. This bug makes the
+@c configuration scripts produced by Autoconf unusable on those systems.
+@c However, some of them can be given options that make the exit status
+@c correct. This is a problem that Autoconf does not currently handle
+@c automatically. If users encounter this problem, they might be able to
+@c solve it by setting @code{LDFLAGS} in the environment to pass whatever
+@c options the linker needs (for example, @option{-Wl,-dn} on @sc{mips
+@c risc/os}).
+
+@code{AC_LINK_IFELSE} is used to compile test programs to test for
functions and global variables. It is also used by @code{AC_CHECK_LIB}
to check for libraries (@pxref{Libraries}), by adding the library being
checked for to @code{LIBS} temporarily and trying to link a small
program.
-@defmac AC_TRY_LINK (@var{includes}, @var{function-body}, @ovar{action-if-found}, @ovar{action-if-not-found})
-@acindex TRY_LINK
-Depending on the current language (@pxref{Language Choice}), create a
-test program to see whether a function whose body consists of
-@var{function-body} can be compiled and linked. If the file compiles
-and links successfully, run shell commands @var{action-if-found},
-otherwise run @var{action-if-not-found}.
-
-This macro double quotes both @var{includes} and @var{function-body}.
-For C and C++, @var{includes} is any @code{#include} statements needed
-by the code in @var{function-body} (@var{includes} will be ignored if
-the currently selected language is Fortran 77). This macro also uses
-@code{CFLAGS} or @code{CXXFLAGS} if either C or C++ is the currently
-selected language, as well as @code{CPPFLAGS}, when compiling. If
-Fortran 77 is the currently selected language then @code{FFLAGS} will be
-used when compiling. However, both @code{LDFLAGS} and @code{LIBS} will
-be used during linking in all cases.
-@end defmac
+@defmac AC_LINK_IFELSE (@var{input}, @ovar{action-if-found}, @ovar{action-if-not-found})
+@acindex LINK_IFELSE
+Run the compiler and the linker of the current language (@pxref{Language
+Choice}) on the @var{input}, run the shell commands @var{action-if-true}
+on success, @var{action-if-false} otherwise. The @var{input} can be made
+by @code{AC_LANG_PROGRAM} and friends.
-@defmac AC_TRY_LINK_FUNC (@var{function}, @ovar{action-if-found}, @ovar{action-if-not-found})
-@acindex TRY_LINK_FUNC
-Depending on the current language (@pxref{Language Choice}), create a
-test program to see whether a program whose body consists of
-a prototype of and a call to @var{function} can be compiled and linked.
+This macro uses @code{CFLAGS} or @code{CXXFLAGS} if either C or C++ is
+the currently selected language, as well as @code{CPPFLAGS}, when
+compiling. If Fortran 77 is the currently selected language then
+@code{FFLAGS} will be used when compiling.
-If the file compiles and links successfully, run shell commands
-@var{action-if-found}, otherwise run @var{action-if-not-found}.
+This macro does not try to execute the program; use @code{AC_RUN_IFELSE}
+if you need to do that (@pxref{Run Time}).
@end defmac
@defmac AC_COMPILE_CHECK (@var{echo-text}, @var{includes}, @var{function-body}, @var{action-if-found}, @ovar{action-if-not-found})
@acindex COMPILE_CHECK
-This is an obsolete version of @code{AC_TRY_LINK} (@pxref{Examining
-Libraries}), with the addition that it prints @samp{checking for
+This is an obsolete version of @code{AC_TRY_COMPILE} (@pxref{Running the
+Compiler}), with the addition that it prints @samp{checking for
@var{echo-text}} to the standard output first, if @var{echo-text} is
non-empty. Use @code{AC_MSG_CHECKING} and @code{AC_MSG_RESULT} instead
to print messages (@pxref{Printing Messages}).
@defmac AC_TEST_CPP
@acindex TEST_CPP
-@code{AC_TRY_CPP}
+@code{AC_TRY_CPP}, replaced with @code{AC_PREPROC_IFELSE}.
@end defmac
@defmac AC_TEST_PROGRAM
This macro double quotes the @var{input}.
@end defmac
+@defmac AC_TRY_LINK (@var{includes}, @var{function-body}, @ovar{action-if-found}, @ovar{action-if-not-found})
+@acindex TRY_LINK
+Same as @samp{AC_LINK_IFELSE([AC_LANG_SOURCE([[@var{includes}]],
+[[@var{function-body}]])], [@var{action-if-true}],
+[@var{action-if-false}])} (@pxref{Running the Compiler}).
+
+This macro double quotes both @var{includes} and @var{function-body}.
+
+Depending on the current language (@pxref{Language Choice}), create a
+test program to see whether a function whose body consists of
+@var{function-body} can be compiled and linked. If the file compiles
+and links successfully, run shell commands @var{action-if-found},
+otherwise run @var{action-if-not-found}.
+
+This macro double quotes both @var{includes} and @var{function-body}.
+
+For C and C++, @var{includes} is any @code{#include} statements needed
+by the code in @var{function-body} (@var{includes} will be ignored if
+the currently selected language is Fortran 77). This macro also uses
+@code{CFLAGS} or @code{CXXFLAGS} if either C or C++ is the currently
+selected language, as well as @code{CPPFLAGS}, when compiling. If
+Fortran 77 is the currently selected language then @code{FFLAGS} will be
+used when compiling. However, both @code{LDFLAGS} and @code{LIBS} will
+be used during linking in all cases.
+@end defmac
+
+@defmac AC_TRY_LINK_FUNC (@var{function}, @ovar{action-if-found}, @ovar{action-if-not-found})
+@acindex TRY_LINK_FUNC
+This macro is equivalent to
+@samp{AC_LINK_IFELSE([AC_LANG_CALL([[@var{includes}]],
+[[@var{function-body}]])], [@var{action-if-true}],
+[@var{action-if-false}])}.
+@end defmac
+
@defmac AC_UID_T
@acindex UID_T
@code{AC_TYPE_UID_T}
[AC_CACHE_CHECK([for library containing $1], [ac_cv_search_$1],
[ac_func_search_save_LIBS=$LIBS
ac_cv_search_$1=no
-AC_TRY_LINK_FUNC([$1], [ac_cv_search_$1="none required"])
+AC_LINK_IFELSE([AC_LANG_CALL([], [$1])],
+ [ac_cv_search_$1="none required"])
if test "$ac_cv_search_$1" = no; then
for ac_lib in $2; do
LIBS="-l$ac_lib $5 $ac_func_search_save_LIBS"
- AC_TRY_LINK_FUNC([$1],
- [ac_cv_search_$1="-l$ac_lib"
+ AC_LINK_IFELSE([AC_LANG_CALL([], [$1])],
+ [ac_cv_search_$1="-l$ac_lib"
break])
done
fi
AC_CACHE_CHECK([for $2 in -l$1], ac_Lib,
[ac_check_lib_save_LIBS=$LIBS
LIBS="-l$1 $5 $LIBS"
-AC_TRY_LINK_FUNC([$2],
- [AS_VAR_SET(ac_Lib, yes)],
- [AS_VAR_SET(ac_Lib, no)])
+AC_LINK_IFELSE([AC_LANG_CALL([], [$2])],
+ [AS_VAR_SET(ac_Lib, yes)],
+ [AS_VAR_SET(ac_Lib, no)])
LIBS=$ac_check_lib_save_LIBS])
AS_IF([test AS_VAR_GET(ac_Lib) = yes],
[m4_default([$3], [AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_LIB$1))
# Don't add to $LIBS permanently.
ac_save_LIBS=$LIBS
LIBS="-lXt $LIBS"
- AC_TRY_LINK([@%:@include <X11/Intrinsic.h>], [XtMalloc (0)],
-[LIBS=$ac_save_LIBS
+ AC_LINK_IFELSE([AC_LANG_PROGRAM([@%:@include <X11/Intrinsic.h>],
+ [XtMalloc (0)])],
+ [LIBS=$ac_save_LIBS
# We can link X programs with no special library path.
ac_x_libraries=],
-[LIBS=$ac_save_LIBS
+ [LIBS=$ac_save_LIBS
for ac_dir in `echo "$ac_x_includes $ac_x_header_dirs" | sed s/include/lib/g`
do
# Don't even attempt the hair of trying to link an X program!
# libraries were built with DECnet support. And Karl Berry says
# the Alpha needs dnet_stub (dnet does not exist).
ac_xsave_LIBS="$LIBS"; LIBS="$LIBS $X_LIBS -lX11"
- AC_TRY_LINK_FUNC(XOpenDisplay, ,
+ AC_LINK_IFELSE([AC_LANG_CALL([], [XOpenDisplay])],
+ [],
[AC_CHECK_LIB(dnet, dnet_ntoa, [X_EXTRA_LIBS="$X_EXTRA_LIBS -ldnet"])
if test $ac_cv_lib_dnet_dnet_ntoa = no; then
AC_CHECK_LIB(dnet_stub, dnet_ntoa,
projects / thirdparty / autoconf.git / commitdiff
