From a971b891bbdd51e2f1111a41ffff9dfd5e171ab4 Mon Sep 17 00:00:00 2001
From: fche <fche>
Date: Mon, 5 Jun 2006 19:45:56 +0000
Subject: 2006-06-05  Frank Ch. Eigler  <fche@elastic.org>

	PR 2645 cont'd.
	* elaborate.cxx (derive_probes): Pass down optional flag
	from alias reference to expansion.
	* testsuite/semok/twentytwo.stp: Test passing-down.
	* stapprobes.5.in: Specify passing-down property of optional flag.
---
 ChangeLog                     |  8 ++++++++
 elaborate.cxx                 | 23 ++++++++++++++---------
 stap.1.in                     |  2 +-
 stapprobes.5.in               |  3 ++-
 testsuite/semok/twentytwo.stp | 11 ++++++++---
 5 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 37dae951..f35abe25 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2006-06-05  Frank Ch. Eigler  <fche@elastic.org>
+
+	PR 2645 cont'd.
+	* elaborate.cxx (derive_probes): Pass down optional flag
+	from alias reference to expansion.
+	* testsuite/semok/twentytwo.stp: Test passing-down.
+	* stapprobes.5.in: Specify passing-down property of optional flag.
+
 2006-06-02  Frank Ch. Eigler  <fche@elastic.org>
 
 	PR 2645 cont'd.
diff --git a/elaborate.cxx b/elaborate.cxx
index e24d26ff..b6d0f226 100644
--- a/elaborate.cxx
+++ b/elaborate.cxx
@@ -480,28 +480,33 @@ derive_probes (systemtap_session& s,
   for (unsigned i = 0; i < p->locations.size(); ++i)
     {
       probe_point *loc = p->locations[i];
-      
+
+      // Pass down optional flag from e.g. alias reference to each
+      // probe_point instance.  We do this by temporarily overriding
+      // the probe_point optional flag.  We could instead deep-copy
+      // and set a flag on the copy permanently.
+
+      bool old_loc_opt = loc->optional;
+      loc->optional = loc->optional || optional;
+
       try
         {
           unsigned num_atbegin = dps.size();
           s.pattern_root->find_and_build (s, p, loc, 0, dps);
           unsigned num_atend = dps.size();
           
-          if (! optional && ! loc->optional && // something required, but
+          if (! loc->optional && // something required, but
               num_atbegin == num_atend) // nothing new derived!
             throw semantic_error ("no match for probe point");
-
-          // XXX: perhaps "optional" should operate at the outside
-          // loop (probe) level.
         }
       catch (const semantic_error& e)
         {
           // XXX: prefer not to print_error at every nest/unroll level
           s.print_error (e);
           cerr << "while: resolving probe point " << *loc << endl;
-          //          if (! exc_outermost)
-          //            throw;
         }
+
+      loc->optional = old_loc_opt;
     }
 }
 
@@ -869,8 +874,8 @@ semantic_pass_symbols (systemtap_session& s)
           probe* p = dome->probes [i];
           vector<derived_probe*> dps;
 
-          // much magic happens here: probe alias expansion,
-          // provider identification
+          // much magic happens here: probe alias expansion, wildcard
+          // matching, low-level derived_probe construction.
           derive_probes (s, p, dps);
 
           for (unsigned j=0; j<dps.size(); j++)
diff --git a/stap.1.in b/stap.1.in
index 3149a4f0..c805f54d 100644
--- a/stap.1.in
+++ b/stap.1.in
@@ -410,7 +410,7 @@ at the given point, it just defines a new probe point name as an alias
 to an existing one. There are two types of alias, i.e. the prologue 
 style and the epilogue style which are identified by "=" and "+="
 respectively. 
-
+.PP
 For prologue style alias, the statement block that follows an alias
 definition is implicitly added as a prologue to any probe that refers
 to the alias. While for the epilogue style alias, the statement block
diff --git a/stapprobes.5.in b/stapprobes.5.in
index f1744d2f..0685ba2d 100644
--- a/stapprobes.5.in
+++ b/stapprobes.5.in
@@ -28,7 +28,8 @@ identifier may be parametrized by a string or number literal, with a
 syntax like a function call.  A component may include a "*"
 character, to expand to other matching probe points.  A probe point
 may be followed by a "?" character, to indicate that it is optional,
-and that no error should result if it fails to expand.
+and that no error should result if it fails to expand.  Optionalness
+passes down through all levels of alias/wildcard expansion.
 
 These are all syntactically valid probe points:
 .SAMPLE
diff --git a/testsuite/semok/twentytwo.stp b/testsuite/semok/twentytwo.stp
index f8f44ffb..b5fcb3a0 100755
--- a/testsuite/semok/twentytwo.stp
+++ b/testsuite/semok/twentytwo.stp
@@ -1,10 +1,15 @@
 #! stap -p2
 
-probe foo.a = kernel.function("no_such_function")?, never { "alias a" }
+probe foo.a = kernel.function("no_such_function")?, never { }
 probe foo.* { }
 
-probe baz.a = kernel.function("no_such_function") { "alias a" }
+probe baz.a = kernel.function("no_such_function") { }
 probe baz.* ? { }
 
-probe bar = kernel.function("no_such_function") { "alias b" }
+probe bar = kernel.function("no_such_function") { }
 probe bar ? { }
+
+probe bar3 = kernel.function("no_such_function") { }
+probe bar2 = bar3 { }
+probe bar2 ? { }
+
-- 
cgit