diff options
| -rw-r--r-- | configure.ac | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/configure.ac b/configure.ac index c85888c851..55aae5f389 100644 --- a/configure.ac +++ b/configure.ac @@ -1021,7 +1021,17 @@ if test -n "$USER_NOPTHREAD"; then # -D_REENTRANT' or some such. elif test -z "$PTHREAD_CFLAGS"; then threads_found=no - for opt in -mt -pthread -lpthread; do + # Attempt to compile and link some code using pthreads to determine + # required linker flags. The order is somewhat important here: We + # first try it without any extra flags, to catch systems where + # pthreads are part of the C library, then go on testing various other + # flags. We do so to avoid false positives. For example, on Mac OS X + # pthreads are part of the C library; moreover, the compiler allows us + # to add "-mt" to the CFLAGS (although it will do nothing except + # trigger a warning about an unused flag). Hence if we checked for + # "-mt" before "" we would end up picking it. But unfortunately this + # would then trigger compiler warnings on every single file we compile. + for opt in "" -mt -pthread -lpthread; do old_CFLAGS="$CFLAGS" CFLAGS="$opt $CFLAGS" AC_MSG_CHECKING([Checking for POSIX Threads with '$opt']) |