bad.txt

semantic error: type mismatch (string): identifier 'a' at test.stp:13:7
        source:     f(a);
                      ^
semantic error: type mismatch (string): identifier 'a' at :13:7
        source:     f(a);
                      ^
semantic error: type was first inferred here (long): identifier 'a' at :12:7
        source:     g(a);
                      ^
Pass 2: analysis failed.  [man error::pass2]

cause-of-the-issue.diff

--- a/session.cxx
+++ b/session.cxx
@@ -2382,6 +2382,7 @@ systemtap_session::print_error (const semantic_error& se)
   if (verbose > 0 || seen_errors[se.errsrc_chain()] < 1)
     {
       seen_errors[se.errsrc_chain()]++;
+      cerr << build_error_msg(se);
       for (const semantic_error *e = &se; e != NULL; e = e->get_chain())
         if (verbose > 1 || seen_errors[e->errsrc] < 1) // dupe-eliminate chained errors too
           {

good.txt

semantic error: type mismatch (string): identifier 'a' at test.stp:13:7
        source:     f(a);
                      ^
semantic error: type was first inferred here (long): identifier 'a' at :12:7
        source:     g(a);
                      ^
Pass 2: analysis failed.  [man error::pass2]