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Don't check how to copy a va_list if we already have va_copy()

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If we already have ISO C va_copy() or its non-standard counterpart
__va_copy(), then there's no need to do an AC_RUN_IFELSE or its
CMake equivalent to detect whether "args2 = args1" or "*args2 = *args1"
works. AC_RUN_IFELSE is problematic during cross-compilation, where the
program cannot be run (you have to know in advance that the test program
will be run and what its result will be), so we want to avoid it whenever
possible.

Signed-off-by: Simon McVittie <smcv@collabora.com>
This commit is contained in:
Simon McVittie 2018-11-15 17:40:33 +00:00
parent c018e0b1b2
commit 6278951f6d
2 changed files with 53 additions and 55 deletions
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38
cmake/ConfigureChecks.cmake
View file

@ -120,26 +120,26 @@ elseif(HAVE___VA_COPY)
else()
# this is used for msvc < 2013
set(DBUS_VA_COPY _DBUS_VA_COPY_ASSIGN)
endif()
CHECK_C_SOURCE_RUNS("
#include <stdarg.h>
#include <stdlib.h>
static void f (int i, ...) {
va_list args1, args2;
va_start (args1, i);
args2 = args1;
if (va_arg (args2, int) != 42 || va_arg (args1, int) != 42)
exit (1);
va_end (args1); va_end (args2);
}
int main() {
f (0, 42);
return 0;
}
" VA_COPY_AS_ARRAY)
if (NOT VA_COPY_AS_ARRAY)
set(DBUS_VA_COPY_AS_ARRAY 1 CACHE STRING "Set to 1 if va_list cannot be copied as a value")
CHECK_C_SOURCE_RUNS("
#include <stdarg.h>
#include <stdlib.h>
static void f (int i, ...) {
va_list args1, args2;
va_start (args1, i);
args2 = args1;
if (va_arg (args2, int) != 42 || va_arg (args1, int) != 42)
exit (1);
va_end (args1); va_end (args2);
}
int main() {
f (0, 42);
return 0;
}
" VA_COPY_AS_ARRAY)
if (NOT VA_COPY_AS_ARRAY)
set(DBUS_VA_COPY_AS_ARRAY 1 CACHE STRING "Set to 1 if va_list cannot be copied as a value")
endif()
endif()
CHECK_C_SOURCE_COMPILES("

70
configure.ac
View file

@ -563,42 +563,40 @@ else if test "x$dbus_cv___va_copy" = "xyes"; then
fi
fi
if test -n "$dbus_va_copy_func"; then
AC_DEFINE_UNQUOTED(DBUS_VA_COPY,$dbus_va_copy_func,[A 'va_copy' style function])
fi
AC_LANG_PUSH(C)
AC_CACHE_CHECK([whether va_lists can be copied by value],
dbus_cv_va_val_copy,
[AC_RUN_IFELSE([AC_LANG_PROGRAM(
[[
#include <stdarg.h>
#include <stdlib.h>
]],
[[
static void f (int i, ...) {
va_list args1, args2;
va_start (args1, i);
args2 = args1;
if (va_arg (args2, int) != 42 || va_arg (args1, int) != 42)
exit (1);
va_end (args1); va_end (args2);
}
int main() {
f (0, 42);
return 0;
}
]])],
[dbus_cv_va_val_copy=yes],
[dbus_cv_va_val_copy=no],
[dbus_cv_va_val_copy=yes])
])
AC_LANG_POP(C)
if test "x$dbus_cv_va_val_copy" = "xno"; then
AC_DEFINE(DBUS_VA_COPY_AS_ARRAY,1, ['va_lists' cannot be copies as values])
fi
AS_IF([test -n "$dbus_va_copy_func"],
[AC_DEFINE_UNQUOTED([DBUS_VA_COPY], [$dbus_va_copy_func], [A 'va_copy' style function])],
[
AC_LANG_PUSH([C])
AC_CACHE_CHECK([whether va_lists can be copied by value],
[dbus_cv_va_val_copy],
[AC_RUN_IFELSE([
AC_LANG_PROGRAM([[
#include <stdarg.h>
#include <stdlib.h>
]],
[[
static void f (int i, ...) {
va_list args1, args2;
va_start (args1, i);
args2 = args1;
if (va_arg (args2, int) != 42 || va_arg (args1, int) != 42)
exit (1);
va_end (args1); va_end (args2);
}
int main() {
f (0, 42);
return 0;
}
]])
],
[dbus_cv_va_val_copy=yes],
[dbus_cv_va_val_copy=no],
[dbus_cv_va_val_copy=yes])
])
AC_LANG_POP([C])
AS_IF([test "x$dbus_cv_va_val_copy" = "xno"],
[AC_DEFINE([DBUS_VA_COPY_AS_ARRAY], 1, [Define if 'va_list' cannot be copied as a value])])
])
#### Atomic integers