From 6278951f6deb4a2a3b2177dfaaa64bd64fa13701 Mon Sep 17 00:00:00 2001 From: Simon McVittie Date: Thu, 15 Nov 2018 17:40:33 +0000 Subject: Don't check how to copy a va_list if we already have va_copy() 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 --- configure.ac | 70 +++++++++++++++++++++++++++++------------------------------- 1 file changed, 34 insertions(+), 36 deletions(-) (limited to 'configure.ac') diff --git a/configure.ac b/configure.ac index 89337836..fa542290 100644 --- a/configure.ac +++ b/configure.ac @@ -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,$dbus_va_copy_func,[A 'va_copy' style function]) -fi - -AC_LANG_PUSH(C) -AC_CACHE_CHECK([whether va_lists can be copied by value], - dbus_cv_va_val_copy, - [AC_RUN_IFELSE([AC_LANG_PROGRAM( -[[ - #include - #include -]], -[[ - static void f (int i, ...) { - va_list args1, args2; - va_start (args1, i); - args2 = args1; - if (va_arg (args2, int) != 42 || va_arg (args1, int) != 42) - exit (1); - va_end (args1); va_end (args2); - } - int main() { - f (0, 42); - return 0; - } -]])], - [dbus_cv_va_val_copy=yes], - [dbus_cv_va_val_copy=no], - [dbus_cv_va_val_copy=yes]) -]) -AC_LANG_POP(C) - -if test "x$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 + #include + ]], + [[ + 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 -- cgit v1.2.1