Clean up and clarify semantic_error chaining

I consolidated the copy-construction that every target_symbol::chain
caller was doing.  I also removed the comments that target_symbol errors
might be chained due to function wildcards, because it's not true --
each derived instance gets a deep_copy of the probe body.  However,
@cast can still chain since it may try multiple modules to resolve the
casting dereference.

6 files changed, 15 insertions, 19 deletions

diff --git a/staptree.cxx b/staptree.cxx
index 4e57ac18..f7ce128e 100644
--- a/staptree.cxx
+++ b/staptree.cxx
@@ -224,8 +224,11 @@ target_symbol::assert_no_components(const std::string& tapset)
 }
 
 
-void target_symbol::chain (semantic_error *e)
+void target_symbol::chain (const semantic_error &er)
 {
+  semantic_error* e = new semantic_error(er);
+  if (!e->tok1)
+    e->tok1 = this->tok;
   assert (e->chain == 0);
   e->chain = this->saved_conversion_error;
   this->saved_conversion_error = e;
diff --git a/staptree.h b/staptree.h
index 895c6667..eff5d3cd 100644
--- a/staptree.h
+++ b/staptree.h
@@ -33,9 +33,7 @@ struct semantic_error: public std::runtime_error
   semantic_error *chain;
 
   ~semantic_error () throw () {}
-  semantic_error (const std::string& msg):
-    runtime_error (msg), tok1 (0), tok2 (0), chain (0) {}
-  semantic_error (const std::string& msg, const token* t1):
+  semantic_error (const std::string& msg, const token* t1=0):
     runtime_error (msg), tok1 (t1), tok2 (0), chain (0) {}
   semantic_error (const std::string& msg, const token* t1,
                   const std::string& m2, const token* t2):
@@ -258,7 +256,7 @@ struct target_symbol: public symbol
   std::string probe_context_var; // NB: this being set implies that target_symbol is *resolved*
   semantic_error* saved_conversion_error; // hand-made linked list
   target_symbol(): addressof(false), saved_conversion_error (0) {}
-  void chain (semantic_error* e);
+  void chain (const semantic_error& er);
   void print (std::ostream& o) const;
   void visit (visitor* u);
   void visit_components (visitor* u);
diff --git a/tapset-mark.cxx b/tapset-mark.cxx
index c672dc7a..6e8191d7 100644
--- a/tapset-mark.cxx
+++ b/tapset-mark.cxx
@@ -198,7 +198,7 @@ mark_var_expanding_visitor::visit_target_symbol (target_symbol* e)
     }
   catch (const semantic_error &er)
     {
-      e->chain (new semantic_error(er));
+      e->chain (er);
       provide (e);
     }
 }
diff --git a/tapset-procfs.cxx b/tapset-procfs.cxx
index c888ff74..34b2b005 100644
--- a/tapset-procfs.cxx
+++ b/tapset-procfs.cxx
@@ -520,7 +520,7 @@ procfs_var_expanding_visitor::visit_target_symbol (target_symbol* e)
     }
   catch (const semantic_error &er)
     {
-      e->chain (new semantic_error(er));
+      e->chain (er);
       provide (e);
     }
 }
diff --git a/tapset-utrace.cxx b/tapset-utrace.cxx
index 25e0b15e..8e2573ab 100644
--- a/tapset-utrace.cxx
+++ b/tapset-utrace.cxx
@@ -601,7 +601,7 @@ utrace_var_expanding_visitor::visit_target_symbol (target_symbol* e)
     }
   catch (const semantic_error &er) 
     {
-      e->chain (new semantic_error(er));
+      e->chain (er);
       provide(e);
       return;
     }
diff --git a/tapsets.cxx b/tapsets.cxx
index 4b4fd513..4c070735 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -2683,12 +2683,7 @@ dwarf_var_expanding_visitor::visit_target_symbol (target_symbol *e)
       // target_symbol to the next pass.  We hope that this value ends
       // up not being referenced after all, so it can be optimized out
       // quietly.
-      semantic_error* saveme = new semantic_error (er); // copy it
-      if (! saveme->tok1) { saveme->tok1 = e->tok; } // fill in token if needed
-      // NB: we can have multiple errors, since a $target variable
-      // may be expanded in several different contexts:
-      //     function ("*") { $var }
-      e->chain (saveme);
+      e->chain (er);
       provide (e);
     }
 }
@@ -2771,9 +2766,9 @@ dwarf_cast_query::handle_query_module()
   catch (const semantic_error& er)
     {
       // NB: we can have multiple errors, since a @cast
-      // may be expanded in several different contexts:
-      //     function ("*") { @cast(...) }
-      e.chain (new semantic_error(er));
+      // may be attempted using several different modules:
+      //     @cast(ptr, "type", "module1:module2:...")
+      e.chain (er);
     }
 }
 
@@ -3998,7 +3993,7 @@ sdt_var_expanding_visitor::visit_target_symbol (target_symbol *e)
     }
   catch (const semantic_error &er)
     {
-      e->chain (new semantic_error(er));
+      e->chain (er);
       provide (e);
     }
 }
@@ -6309,7 +6304,7 @@ tracepoint_var_expanding_visitor::visit_target_symbol (target_symbol* e)
     }
   catch (const semantic_error &er)
     {
-      e->chain (new semantic_error(er));
+      e->chain (er);
       provide (e);
     }
 }