[PATCH] use a compile time assert to allow configure to work when
cross compiling
Jim Radford
radford at galvanix.net
Tue Oct 7 04:41:13 GMT 2008
This patch allows ./configure to run out of the box when cross
compiling samba-3.2.4 by using compile asserts instead of runtime
checks.
This technique has only been tested with gcc, so I added an assert for
the compile assert itself to catch compilers that it doesn't work
with.
-Jim
diff -ru samba-3.2.4.orig/source/configure.in samba-3.2.4/source/configure.in
--- samba-3.2.4.orig/source/configure.in 2008-10-06 21:12:35.000000000 -0700
+++ samba-3.2.4/source/configure.in 2008-10-06 21:36:10.000000000 -0700
@@ -275,6 +275,8 @@
fi
AC_SUBST(BROKEN_CC)
+AC_TRY_COMPILE([],[(void)sizeof(char[-1])],AC_MSG_ERROR([configure's compilation assert doesn't work with $CC]))
+
dnl Check if the C compiler understands -Werror
AC_CACHE_CHECK([that the C compiler understands -Werror],samba_cv_HAVE_Werror, [
AC_TRY_RUN_STRICT([
@@ -325,25 +327,11 @@
# a runtime test is needed here
AC_SUBST(PIDL_ARGS)
AC_CACHE_CHECK([that the C compiler understands negative enum values],samba_cv_CC_NEGATIVE_ENUM_VALUES, [
- AC_TRY_RUN(
+ AC_TRY_COMPILE([],
[
- #include <stdio.h>
enum negative_values { NEGATIVE_VALUE = 0xFFFFFFFF };
- int main(void) {
- enum negative_values v1 = NEGATIVE_VALUE;
- unsigned v2 = NEGATIVE_VALUE;
-
- if (v1 != 0xFFFFFFFF) {
- printf("%u != 0xFFFFFFFF\n", v1);
- return 1;
- }
- if (v2 != 0xFFFFFFFF) {
- printf("%u != 0xFFFFFFFF\n", v2);
- return 1;
- }
-
- return 0;
- }
+ (void)sizeof(char[1-2*( (unsigned)NEGATIVE_VALUE != 0xFFFFFFFF)]);
+ (void)sizeof(char[1-2*((enum negative_values)NEGATIVE_VALUE != 0xFFFFFFFF)]);
],
samba_cv_CC_NEGATIVE_ENUM_VALUES=yes,samba_cv__CC_NEGATIVE_ENUM_VALUES=no)])
if test x"$samba_cv_CC_NEGATIVE_ENUM_VALUES" != x"yes"; then
@@ -1187,22 +1175,12 @@
case "$host_os" in
*linux*)
# glibc <= 2.3.2 has a broken getgrouplist
- AC_TRY_RUN([
-#include <unistd.h>
+ AC_TRY_COMPILE([
#include <sys/utsname.h>
-main() {
- /* glibc up to 2.3 has a broken getgrouplist */
+],[
#if defined(__GLIBC__) && defined(__GLIBC_MINOR__)
- int libc_major = __GLIBC__;
- int libc_minor = __GLIBC_MINOR__;
-
- if (libc_major < 2)
- exit(1);
- if ((libc_major == 2) && (libc_minor <= 3))
- exit(1);
+ (void)sizeof(char[1-2*(__GLIBC__ < 2 || __GLIBC__ == 2 && __GLIBC_MINOR__ <= 3)]);
#endif
- exit(0);
-}
], [linux_getgrouplist_ok=yes], [linux_getgrouplist_ok=no])
if test x"$linux_getgrouplist_ok" = x"yes"; then
AC_DEFINE(HAVE_GETGROUPLIST, 1, [Have good getgrouplist])
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