From 66198f447f45a87718b6457756976baa8defb2fd Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Fri, 10 Apr 2020 13:30:00 -0400
Subject: Use -latomic if needed with gcc

---
 configure | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

(limited to 'configure')

diff --git a/configure b/configure
index 5a9c614f..9703878f 100755
--- a/configure
+++ b/configure
@@ -16975,6 +16975,49 @@ ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
+ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to use -latomic" >&5
+$as_echo_n "checking whether to use -latomic... " >&6; }
+oLDFLAGS="$LDFLAGS"
+LDFLAGS="$LDFLAGS -Wl,--as-needed -latomic"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <atomic>
+    int main()
+    {
+        static std::atomic<int> a{0};
+        a = a.fetch_add(1);
+        return 0;
+    }
+
+_ACEOF
+if ac_fn_cxx_try_link "$LINENO"; then :
+  qpdf_USE_ATOMIC=1
+else
+  qpdf_USE_ATOMIC=0
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+if test "$qpdf_USE_ATOMIC" = "1"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+  LDFLAGS="$oLDFLAGS"
+fi
+ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+
 if test "x$qpdf_OS_SECURE_RANDOM" = "x1"; then
   OLIBS=$LIBS
   LIBS="$LIBS Advapi32.lib"
-- 
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