+# Check that the headers are self-contained, and protected against
+# multiple inclusions. While at it, check they are sane for C++.
+for h in *.h *.hh
+do
+ # No shell expansion with AT_DATA.
+ cat >$h.cc <<EOF
+AT_DATA_SOURCE_PROLOGUE
+#include "$h"
+#include "$h"
+EOF
+ AT_COMPILE_CXX([$h.o])
+done
+