Squash elision warnings on synthetic functions

* staptree.h (functiondecl): Add a synthetic flag.
* elaborate.cxx (semantic_pass_opt1): Don't warn about synthetic funcs.
* tapsets.cxx (dwarf_var_expanding_visitor::visit_target_symbol): Mark
  the new function as synthetic.
  (dwarf_cast_expanding_visitor::visit_cast_op): Ditto.
  (tracepoint_var_expanding_visitor::visit_target_symbol_arg): Ditto.
* tapset-perfmon.cxx
  (perfmon_var_expanding_visitor::visit_target_symbol): Ditto.
* tapset-procfs.cxx (procfs_var_expanding_visitor::visit_target_symbol):
  Ditto.
* testsuite/semok/thirtyeight.stp: New check with -W and @defined.

1 files changed, 10 insertions, 0 deletions

diff --git a/testsuite/semok/thirtyeight.stp b/testsuite/semok/thirtyeight.stp
new file mode 100755
index 00000000..aedbab08
--- /dev/null
+++ b/testsuite/semok/thirtyeight.stp
@@ -0,0 +1,10 @@
+#! stap -Wp2
+
+# Each of the @defined should be a valid symbol, and sometimes their expansion
+# leads to a new function declaration.  We don't want to get warnings when such
+# functions turn out to be unused and are elided.
+
+probe kernel.function("sys_open") { println(@defined($mode) ? 1 : $nosuchvar) }
+probe kernel.trace("sched_switch")? { println(@defined($next->pid) ? 1 : $nosuchvar) }
+probe procfs.write { println(@defined($value) ? 1 : $nosuchvar) }
+probe begin { println(@defined(@cast(0, "task_struct")->pid) ? 1 : $nosuchvar) }