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-rw-r--r--configure.ac15
1 files changed, 15 insertions, 0 deletions
diff --git a/configure.ac b/configure.ac
index cea02b7daf..1540c40f9c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -615,6 +615,21 @@ fi
AM_CONDITIONAL(BUILD_READPASSPHRASE_C,
test "x$ac_cv_func_readpassphrase" = "xno" && test "$bwin32" = "false")
+AC_MSG_CHECKING([whether free(NULL) works])
+AC_RUN_IFELSE([AC_LANG_PROGRAM([
+ #include <stdlib.h>
+], [
+char *p = NULL;
+free(p);
+])],
+[free_null_ok=true; AC_MSG_RESULT(yes)],
+[free_null_ok=false; AC_MSG_RESULT(no)],
+[free_null_ok=cross; AC_MSG_RESULT(cross)])
+
+if test "$free_null_ok" = "false"; then
+ AC_MSG_ERROR([Your libc implementation doesn't allow free(NULL), as required by C99.])
+fi
+
dnl ------------------------------------------------------
dnl Where do you live, libevent? And how do we call you?