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6.2.3 Generating Sources
Autoconf provides a set of macros that can be used to generate test
source files. They are written to be language generic, i.e., they
actually depend on the current language (see Language Choice) to
“format” the output properly.
— Macro: AC_LANG_CONFTEST ( source)
Save the source text in the current test source file:
conftest.extension where the extension depends on the
current language.
Note that the source is evaluated exactly once, like regular
Autoconf macro arguments, and therefore (i) you may pass a macro
invocation, (ii) if not, be sure to double quote if needed.
— Macro: AC_LANG_SOURCE ( source)
Expands into the source, with the definition of
all the AC_DEFINE performed so far.
For instance executing (observe the double quotation!):
AC_INIT([Hello], [1.0], [[email protected]])
AC_DEFINE([HELLO_WORLD], ["Hello, World\n"],
[Greetings string.])
AC_LANG(C)
AC_LANG_CONFTEST(
[AC_LANG_SOURCE([[const char hw[] = "Hello, World\n";]])])
gcc -E -dD -o - conftest.c
results in:
...
# 1 "conftest.c"
#define PACKAGE_NAME "Hello"
#define PACKAGE_TARNAME "hello"
#define PACKAGE_VERSION "1.0"
#define PACKAGE_STRING "Hello 1.0"
#define PACKAGE_BUGREPORT "[email protected]"
#define HELLO_WORLD "Hello, World\n"
const char hw[] = "Hello, World\n";
When the test language is Fortran or Erlang, the AC_DEFINE definitions
are not automatically translated into constants in the source code by this
macro.
— Macro: AC_LANG_PROGRAM ( prologue, body)
Expands into a source file which consists of the prologue, and
then body as body of the main function (e.g., main in
C). Since it uses AC_LANG_SOURCE, the features of the latter are
available.
For instance:
AC_INIT([Hello], [1.0], [[email protected]])
AC_DEFINE([HELLO_WORLD], ["Hello, World\n"],
[Greetings string.])
AC_LANG_CONFTEST(
[AC_LANG_PROGRAM([[const char hw[] = "Hello, World\n";]],
[[fputs (hw, stdout);]])])
gcc -E -dD -o - conftest.c
results in:
...
# 1 "conftest.c"
#define PACKAGE_NAME "Hello"
#define PACKAGE_TARNAME "hello"
#define PACKAGE_VERSION "1.0"
#define PACKAGE_STRING "Hello 1.0"
#define PACKAGE_BUGREPORT "[email protected]"
#define HELLO_WORLD "Hello, World\n"
const char hw[] = "Hello, World\n";
int
main ()
{
fputs (hw, stdout);
;
return 0;
}
In Erlang tests, the created source file is that of an Erlang module called
conftest (conftest.erl). This module defines and exports at least
one start/0 function, which is called to perform the test. The
prologue is optional code that is inserted between the module header and
the start/0 function definition. body is the body of the
start/0 function without the final period (see Runtime, about
constraints on this function's behaviour).
For instance:
AC_INIT([Hello], [1.0], [[email protected]])
AC_LANG(Erlang)
AC_LANG_CONFTEST(
[AC_LANG_PROGRAM([[-define(HELLO_WORLD, "Hello, world!").]],
[[io:format("~s~n", [?HELLO_WORLD])]])])
cat conftest.erl
results in:
-module(conftest).
-export([start/0]).
-define(HELLO_WORLD, "Hello, world!").
start() ->
io:format("~s~n", [?HELLO_WORLD])
.
— Macro: AC_LANG_CALL ( prologue, function)
Expands into a source file which consists of the prologue, and
then a call to the function as body of the main function (e.g.,
main in C). Since it uses AC_LANG_PROGRAM, the feature
of the latter are available.
This function will probably be replaced in the future by a version
which would enable specifying the arguments. The use of this macro is
not encouraged, as it violates strongly the typing system.
This macro cannot be used for Erlang tests.
— Macro: AC_LANG_FUNC_LINK_TRY ( function)
Expands into a source file which uses the function in the body of
the main function (e.g., main in C). Since it uses
AC_LANG_PROGRAM, the features of the latter are available.
As 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).
This macro cannot be used for Erlang tests.
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