Fix configuration negotiation to throw postpone_dependency for collected dependency which belongs to not (being) negotiated cluster

2 files changed, 507 insertions, 26 deletions

diff --git a/bpkg/pkg-build-collect.cxx b/bpkg/pkg-build-collect.cxx
index a52bba5..de944a4 100644
--- a/bpkg/pkg-build-collect.cxx
+++ b/bpkg/pkg-build-collect.cxx
@@ -3164,35 +3164,60 @@ namespace bpkg
                     i->second.with_config = true;
                 }
 
-                // Prematurely collected before we saw any config clauses.
+                // Throw postpone_dependency if the dependency is prematurely
+                // collected before we saw any config clauses.
                 //
-                if (p->recursive_collection &&
-                    postponed_cfgs.find_dependency (dpk) == nullptr)
+                // Note that we don't throw if the dependency already belongs
+                // to some (being) negotiated cluster since we will
+                // up-negotiate its configuration (at the end of the loop)
+                // instead.
+                //
+                if (p->recursive_collection)
                 {
-                  if (reeval)
-                  {
-                    l5 ([&]{trace << "cannot re-evaluate existing dependent "
-                                  << pkg.available_name_version_db ()
-                                  << " due to dependencys "
-                                  << p->available_name_version_db ()
-                                  << " (collected prematurely), "
-                                  << "throwing postpone_dependency";});
-                  }
-                  else
+                  const postponed_configuration* pcfg (
+                    postponed_cfgs.find_dependency (dpk));
+
+                  // Note that it may well happen that a dependency was added
+                  // to a not-yet (being) negotiated cluster at the initial
+                  // collection phase, then the dependency was recursively
+                  // collected via some different dependent without
+                  // configuration clause during the postponed collection
+                  // phase (which was not prevented since its entry was
+                  // removed from postponed_deps at the end of the initial
+                  // collection phase), and now we are trying to collect this
+                  // dependency via some third dependent with the
+                  // configuration clause during the postponed collection
+                  // phase. If that's the case, we will throw
+                  // postpone_dependency and this is the reason why we check
+                  // if the cluster is (being) negotiated.
+                  //
+                  if (!(pcfg != nullptr && pcfg->negotiated))
                   {
-                    l5 ([&]{trace << "cannot cfg-postpone dependency "
-                                  << p->available_name_version_db ()
-                                  << " of dependent "
-                                  << pkg.available_name_version_db ()
-                                  << " (collected prematurely), "
-                                  << "throwing postpone_dependency";});
-                  }
+                    if (reeval)
+                    {
+                      l5 ([&]{trace << "cannot re-evaluate existing dependent "
+                                    << pkg.available_name_version_db ()
+                                    << " due to dependency "
+                                    << p->available_name_version_db ()
+                                    << " (collected prematurely), "
+                                    << "throwing postpone_dependency";});
+                    }
+                    else
+                    {
+                      l5 ([&]{trace << "cannot cfg-postpone dependency "
+                                    << p->available_name_version_db ()
+                                    << " of dependent "
+                                    << pkg.available_name_version_db ()
+                                    << " (collected prematurely), "
+                                    << "throwing postpone_dependency";});
+                    }
 
-                  // Don't print the "while satisfying..." chain.
-                  //
-                  dep_chain.clear ();
+                    // Don't print the "while satisfying..." chain.
+                    //
+                    dep_chain.clear ();
 
-                  throw postpone_dependency (move (dpk));
+                    throw postpone_dependency (move (dpk));
+                  }
                 }
 
                 if (!reeval)
@@ -3484,8 +3509,9 @@ namespace bpkg
               // To recap, r.second values mean:
               //
               //   absent  -- shadow cluster-based merge is/being negotiated
-              //   false   -- some non or being negotiated
-              //   true    -- all have been negotiated
+              //   false   -- some non or being negotiated clusters are merged
+              //   true    -- no clusters are merged or all merged have been
+              //              negotiated
               //
               if (r.second && !*r.second)
               {
diff --git a/tests/pkg-build.testscript b/tests/pkg-build.testscript
index ee4ea99..48a886f 100644
--- a/tests/pkg-build.testscript
+++ b/tests/pkg-build.testscript
@@ -8155,6 +8155,461 @@ test.arguments += --sys-no-query
         $pkg_drop fux bex fix buz
       }
 
+      : premature-in-cluster
+      :
+      : Test recollecting from scratch if the prematurely collected dependency
+      : belongs (as a dependency) to a non-negotiated cluster.
+      :
+      {
+        $clone_cfg;
+
+        #  Dependencies:
+        #
+        #  bas: depends: libbar(c)
+        #       depends: bus(c)
+        #
+        #  bax: depends: libfoo(c)
+        #       depends: {libbox libbar} (c)
+        #
+        #  bix: depends: {libbar bar} (c)
+        #       depends: bux
+        #
+        #  buz: depends: bux(c)
+        #
+        #  buc: depends: libfoo(c)
+        #       depends: bux(c)
+        #
+        #  bus: depends: libbaz(c)
+        #       depends: foo(c)
+        #
+        #  bux: depends: libbar(c)
+        #
+        #  bar: depends: libbar(c)
+        #
+        #  foo: depends: libfoo(c)
+        #
+        $* bas bax bix buz buc 2>>~%EOE%;
+          %.*
+          trace: pkg_build: refine package collection/plan execution from scratch
+          %.*
+          trace: collect_build: add bas/1.0.0
+          trace: collect_build: add bax/1.0.0
+          trace: collect_build: add bix/1.0.0
+          trace: collect_build: add buz/1.0.0
+          trace: collect_build: add buc/1.0.0
+          trace: collect_build_prerequisites: begin bas/1.0.0
+          %.*
+          trace: collect_build: add libbar/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bas/1.0.0
+          trace: postponed_configurations::add: create {bas | libbar->{bas/1,1}}
+          trace: collect_build_prerequisites: postpone bas/1.0.0
+          trace: collect_build_prerequisites: begin bax/1.0.0
+          %.*
+          trace: collect_build: add libfoo/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libfoo/1.0.0 of dependent bax/1.0.0
+          trace: postponed_configurations::add: create {bax | libfoo->{bax/1,1}}
+          trace: collect_build_prerequisites: postpone bax/1.0.0
+          trace: collect_build_prerequisites: begin bix/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bix/1.0.0
+          trace: collect_build: add bar/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency bar/1.0.0 of dependent bix/1.0.0
+          trace: postponed_configurations::add: add {bix 1,1: libbar bar} to {bas | libbar->{bas/1,1}}
+          trace: collect_build_prerequisites: postpone bix/1.0.0
+          trace: collect_build_prerequisites: begin buz/1.0.0
+          %.*
+          trace: collect_build: add bux/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency bux/1.0.0 of dependent buz/1.0.0
+          trace: postponed_configurations::add: create {buz | bux->{buz/1,1}}
+          trace: collect_build_prerequisites: postpone buz/1.0.0
+          trace: collect_build_prerequisites: begin buc/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency libfoo/1.0.0 of dependent buc/1.0.0
+          trace: postponed_configurations::add: add {buc 1,1: libfoo} to {bax | libfoo->{bax/1,1}}
+          trace: collect_build_prerequisites: postpone buc/1.0.0
+          trace: collect_build_postponed (0): begin
+          trace: collect_build_postponed (1): begin {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}
+          %.*
+          trace: collect_build_postponed (1): cfg-negotiate begin {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}
+          %.*
+          trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+          trace: collect_build_prerequisites: begin libbar/1.0.0
+          trace: collect_build_prerequisites: end libbar/1.0.0
+          trace: collect_build_prerequisites: begin bar/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bar/1.0.0
+          trace: postponed_configurations::add: add {bar 1,1: libbar} to {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}?
+          trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bar/1.0.0 is negotiated
+          trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent bar/1.0.0 is already (being) recursively collected, skipping
+          trace: collect_build_prerequisites: end bar/1.0.0
+          trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+          trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent bas/1.0.0
+          trace: collect_build_prerequisites: resume bas/1.0.0
+          %.*
+          trace: collect_build: add bus/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency bus/1.0.0 of dependent bas/1.0.0
+          trace: postponed_configurations::add: create {bas | bus->{bas/2,1}}
+          trace: collect_build_prerequisites: postpone bas/1.0.0
+          trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent bix/1.0.0
+          trace: collect_build_prerequisites: resume bix/1.0.0
+          %.*
+          trace: collect_build_prerequisites: no cfg-clause for dependency bux/1.0.0 of dependent bix/1.0.0
+          trace: collect_build_prerequisites: begin bux/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bux/1.0.0
+          trace: postponed_configurations::add: add {bux 1,1: libbar} to {bar bas bix | libbar->{bar/1,1 bas/1,1 bix/1,1} bar->{bix/1,1}}?
+          %.*
+          trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bux/1.0.0 is negotiated
+          trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent bux/1.0.0 is already (being) recursively collected, skipping
+          trace: collect_build_prerequisites: end bux/1.0.0
+          trace: collect_build_prerequisites: end bix/1.0.0
+          trace: collect_build_postponed (1): cfg-negotiate end {bar bas bix bux | libbar->{bar/1,1 bas/1,1 bix/1,1 bux/1,1} bar->{bix/1,1}}!
+          trace: collect_build_postponed (2): begin {bax buc | libfoo->{bax/1,1 buc/1,1}}
+          %.*
+          trace: collect_build_postponed (2): cfg-negotiate begin {bax buc | libfoo->{bax/1,1 buc/1,1}}
+          %.*
+          trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+          trace: collect_build_prerequisites: begin libfoo/1.0.0
+          trace: collect_build_prerequisites: end libfoo/1.0.0
+          trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+          trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+          trace: collect_build_prerequisites: resume bax/1.0.0
+          %.*
+          trace: collect_build: add libbox/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+          trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {bar bas bix bux | libbar->{bar/1,1 bas/1,1 bix/1,1 bux/1,1} bar->{bix/1,1}}!
+          %.*
+          trace: collect_build_prerequisites: cfg-postponing dependent bax/1.0.0 involves (being) negotiated configurations and results in {bar bas bax bix bux | libbar->{bar/1,1 bas/1,1 bax/2,1 bix/1,1 bux/1,1} bar->{bix/1,1} libbox->{bax/2,1}}!, throwing retry_configuration
+          trace: collect_build_postponed (0): cfg-negotiation of {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}} failed due to dependent bax, refining configuration
+          trace: collect_build_postponed (1): begin {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}
+          %.*
+          trace: collect_build_postponed (1): cfg-negotiate begin {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}
+          trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+          trace: collect_build_prerequisites: begin libbar/1.0.0
+          trace: collect_build_prerequisites: end libbar/1.0.0
+          trace: collect_build_prerequisites: begin bar/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bar/1.0.0
+          trace: postponed_configurations::add: add {bar 1,1: libbar} to {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}?
+          trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bar/1.0.0 is negotiated
+          trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent bar/1.0.0 is already (being) recursively collected, skipping
+          trace: collect_build_prerequisites: end bar/1.0.0
+          trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+          trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent bas/1.0.0
+          trace: collect_build_prerequisites: resume bas/1.0.0
+          %.*
+          trace: collect_build: add bus/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency bus/1.0.0 of dependent bas/1.0.0
+          trace: postponed_configurations::add: create {bas | bus->{bas/2,1}}
+          trace: collect_build_prerequisites: postpone bas/1.0.0
+          trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent bix/1.0.0
+          trace: collect_build_prerequisites: resume bix/1.0.0
+          %.*
+          trace: collect_build_prerequisites: no cfg-clause for dependency bux/1.0.0 of dependent bix/1.0.0
+          trace: collect_build_prerequisites: begin bux/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bux/1.0.0
+          trace: postponed_configurations::add: add {bux 1,1: libbar} to {bar bas bix | libbar->{bar/1,1 bas/1,1 bix/1,1} bar->{bix/1,1}}?
+          trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bux/1.0.0 is negotiated
+          trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent bux/1.0.0 is already (being) recursively collected, skipping
+          trace: collect_build_prerequisites: end bux/1.0.0
+          trace: collect_build_prerequisites: end bix/1.0.0
+          trace: collect_build_postponed (1): cfg-negotiate end {bar bas bix bux | libbar->{bar/1,1 bas/1,1 bix/1,1 bux/1,1} bar->{bix/1,1}}!
+          trace: collect_build_postponed (2): begin {bax buc | libfoo->{bax/1,1 buc/1,1}}
+          %.*
+          trace: collect_build_postponed (2): cfg-negotiate begin {bax buc | libfoo->{bax/1,1 buc/1,1}}
+          trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+          trace: collect_build_prerequisites: begin libfoo/1.0.0
+          trace: collect_build_prerequisites: end libfoo/1.0.0
+          trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+          trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+          trace: collect_build_prerequisites: resume bax/1.0.0
+          %.*
+          trace: collect_build: add libbox/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+          trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {bar bas bix bux | libbar->{bar/1,1 bas/1,1 bix/1,1 bux/1,1} bar->{bix/1,1}}!
+          trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bax/1.0.0 is negotiated
+          trace: collect_build_prerequisites: collecting cfg-postponed dependency libbox/1.0.0 of dependent bax/1.0.0
+          trace: collect_build_prerequisites: begin libbox/1.0.0
+          trace: collect_build_prerequisites: end libbox/1.0.0
+          trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent bax/1.0.0 is already (being) recursively collected, skipping
+          trace: collect_build_prerequisites: end bax/1.0.0
+          trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent buc/1.0.0
+          trace: collect_build_prerequisites: resume buc/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cannot cfg-postpone dependency bux/1.0.0 of dependent buc/1.0.0 (collected prematurely), throwing postpone_dependency
+          trace: pkg_build: collection failed due to prematurely collected dependency (bux), retry from scratch
+          %.*
+          trace: pkg_build: refine package collection/plan execution from scratch
+          %.*
+          trace: collect_build: add bas/1.0.0
+          trace: collect_build: add bax/1.0.0
+          trace: collect_build: add bix/1.0.0
+          trace: collect_build: add buz/1.0.0
+          trace: collect_build: add buc/1.0.0
+          trace: collect_build_prerequisites: begin bas/1.0.0
+          %.*
+          trace: collect_build: add libbar/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bas/1.0.0
+          trace: postponed_configurations::add: create {bas | libbar->{bas/1,1}}
+          trace: collect_build_prerequisites: postpone bas/1.0.0
+          trace: collect_build_prerequisites: begin bax/1.0.0
+          %.*
+          trace: collect_build: add libfoo/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libfoo/1.0.0 of dependent bax/1.0.0
+          trace: postponed_configurations::add: create {bax | libfoo->{bax/1,1}}
+          trace: collect_build_prerequisites: postpone bax/1.0.0
+          trace: collect_build_prerequisites: begin bix/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bix/1.0.0
+          trace: collect_build: add bar/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency bar/1.0.0 of dependent bix/1.0.0
+          trace: postponed_configurations::add: add {bix 1,1: libbar bar} to {bas | libbar->{bas/1,1}}
+          trace: collect_build_prerequisites: postpone bix/1.0.0
+          trace: collect_build_prerequisites: begin buz/1.0.0
+          %.*
+          trace: collect_build: add bux/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency bux/1.0.0 of dependent buz/1.0.0
+          trace: postponed_configurations::add: create {buz | bux->{buz/1,1}}
+          trace: collect_build_prerequisites: postpone buz/1.0.0
+          trace: collect_build_prerequisites: begin buc/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency libfoo/1.0.0 of dependent buc/1.0.0
+          trace: postponed_configurations::add: add {buc 1,1: libfoo} to {bax | libfoo->{bax/1,1}}
+          trace: collect_build_prerequisites: postpone buc/1.0.0
+          trace: collect_build_postponed (0): begin
+          trace: collect_build_postponed (1): begin {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}
+          %.*
+          trace: collect_build_postponed (1): cfg-negotiate begin {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}
+          trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+          trace: collect_build_prerequisites: begin libbar/1.0.0
+          trace: collect_build_prerequisites: end libbar/1.0.0
+          trace: collect_build_prerequisites: begin bar/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bar/1.0.0
+          trace: postponed_configurations::add: add {bar 1,1: libbar} to {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}?
+          trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bar/1.0.0 is negotiated
+          trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent bar/1.0.0 is already (being) recursively collected, skipping
+          trace: collect_build_prerequisites: end bar/1.0.0
+          trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+          trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent bas/1.0.0
+          trace: collect_build_prerequisites: resume bas/1.0.0
+          %.*
+          trace: collect_build: add bus/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency bus/1.0.0 of dependent bas/1.0.0
+          trace: postponed_configurations::add: create {bas | bus->{bas/2,1}}
+          trace: collect_build_prerequisites: postpone bas/1.0.0
+          trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent bix/1.0.0
+          trace: collect_build_prerequisites: resume bix/1.0.0
+          %.*
+          trace: collect_build_prerequisites: dep-postpone dependency bux/1.0.0 of dependent bix/1.0.0
+          trace: collect_build_prerequisites: end bix/1.0.0
+          trace: collect_build_postponed (1): cfg-negotiate end {bar bas bix | libbar->{bar/1,1 bas/1,1 bix/1,1} bar->{bix/1,1}}!
+          trace: collect_build_postponed (2): begin {bax buc | libfoo->{bax/1,1 buc/1,1}}
+          %.*
+          trace: collect_build_postponed (2): cfg-negotiate begin {bax buc | libfoo->{bax/1,1 buc/1,1}}
+          trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+          trace: collect_build_prerequisites: begin libfoo/1.0.0
+          trace: collect_build_prerequisites: end libfoo/1.0.0
+          trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+          trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+          trace: collect_build_prerequisites: resume bax/1.0.0
+          %.*
+          trace: collect_build: add libbox/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+          trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {bar bas bix | libbar->{bar/1,1 bas/1,1 bix/1,1} bar->{bix/1,1}}!
+          trace: collect_build_prerequisites: cfg-postponing dependent bax/1.0.0 involves (being) negotiated configurations and results in {bar bas bax bix | libbar->{bar/1,1 bas/1,1 bax/2,1 bix/1,1} bar->{bix/1,1} libbox->{bax/2,1}}!, throwing retry_configuration
+          trace: collect_build_postponed (0): cfg-negotiation of {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}} failed due to dependent bax, refining configuration
+          trace: collect_build_postponed (1): begin {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}
+          %.*
+          trace: collect_build_postponed (1): cfg-negotiate begin {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}
+          trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+          trace: collect_build_prerequisites: begin libbar/1.0.0
+          trace: collect_build_prerequisites: end libbar/1.0.0
+          trace: collect_build_prerequisites: begin bar/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bar/1.0.0
+          trace: postponed_configurations::add: add {bar 1,1: libbar} to {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}?
+          trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bar/1.0.0 is negotiated
+          trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent bar/1.0.0 is already (being) recursively collected, skipping
+          trace: collect_build_prerequisites: end bar/1.0.0
+          trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+          trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent bas/1.0.0
+          trace: collect_build_prerequisites: resume bas/1.0.0
+          %.*
+          trace: collect_build: add bus/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency bus/1.0.0 of dependent bas/1.0.0
+          trace: postponed_configurations::add: create {bas | bus->{bas/2,1}}
+          trace: collect_build_prerequisites: postpone bas/1.0.0
+          trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent bix/1.0.0
+          trace: collect_build_prerequisites: resume bix/1.0.0
+          %.*
+          trace: collect_build_prerequisites: dep-postpone dependency bux/1.0.0 of dependent bix/1.0.0
+          trace: collect_build_prerequisites: end bix/1.0.0
+          trace: collect_build_postponed (1): cfg-negotiate end {bar bas bix | libbar->{bar/1,1 bas/1,1 bix/1,1} bar->{bix/1,1}}!
+          trace: collect_build_postponed (2): begin {bax buc | libfoo->{bax/1,1 buc/1,1}}
+          %.*
+          trace: collect_build_postponed (2): cfg-negotiate begin {bax buc | libfoo->{bax/1,1 buc/1,1}}
+          trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+          trace: collect_build_prerequisites: begin libfoo/1.0.0
+          trace: collect_build_prerequisites: end libfoo/1.0.0
+          trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+          trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+          trace: collect_build_prerequisites: resume bax/1.0.0
+          %.*
+          trace: collect_build: add libbox/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+          trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {bar bas bix | libbar->{bar/1,1 bas/1,1 bix/1,1} bar->{bix/1,1}}!
+          trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bax/1.0.0 is negotiated
+          trace: collect_build_prerequisites: collecting cfg-postponed dependency libbox/1.0.0 of dependent bax/1.0.0
+          trace: collect_build_prerequisites: begin libbox/1.0.0
+          trace: collect_build_prerequisites: end libbox/1.0.0
+          trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent bax/1.0.0 is already (being) recursively collected, skipping
+          trace: collect_build_prerequisites: end bax/1.0.0
+          trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent buc/1.0.0
+          trace: collect_build_prerequisites: resume buc/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency bux/1.0.0 of dependent buc/1.0.0
+          trace: postponed_configurations::add: add {buc 2,1: bux} to {buz | bux->{buz/1,1}}
+          trace: collect_build_prerequisites: postpone buc/1.0.0
+          trace: collect_build_postponed (2): cfg-negotiate end {bax buc | libfoo->{bax/1,1 buc/1,1}}!
+          trace: collect_build_postponed (3): begin {buc buz | bux->{buc/2,1 buz/1,1}}
+          %.*
+          trace: collect_build_postponed (3): cfg-negotiate begin {buc buz | bux->{buc/2,1 buz/1,1}}
+          %.*
+          trace: collect_build_postponed (3): recursively collect cfg-negotiated dependencies
+          trace: collect_build_prerequisites: begin bux/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bux/1.0.0
+          trace: postponed_configurations::add: add {bux 1,1: libbar} to {bar bas bax bix | libbar->{bar/1,1 bas/1,1 bax/2,1 bix/1,1} bar->{bix/1,1} libbox->{bax/2,1}}!
+          trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bux/1.0.0 is negotiated
+          trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent bux/1.0.0 is already (being) recursively collected, skipping
+          trace: collect_build_prerequisites: end bux/1.0.0
+          trace: collect_build_postponed (3): recursively collect cfg-negotiated dependents
+          trace: collect_build_postponed (3): select cfg-negotiated dependency alternative for dependent buc/1.0.0
+          trace: collect_build_prerequisites: resume buc/1.0.0
+          trace: collect_build_prerequisites: end buc/1.0.0
+          trace: collect_build_postponed (3): select cfg-negotiated dependency alternative for dependent buz/1.0.0
+          trace: collect_build_prerequisites: resume buz/1.0.0
+          trace: collect_build_prerequisites: end buz/1.0.0
+          trace: collect_build_postponed (3): cfg-negotiate end {buc buz | bux->{buc/2,1 buz/1,1}}!
+          trace: collect_build_postponed (4): begin {bas | bus->{bas/2,1}}
+          %.*
+          trace: collect_build_postponed (4): cfg-negotiate begin {bas | bus->{bas/2,1}}
+          %.*
+          trace: collect_build_postponed (4): recursively collect cfg-negotiated dependencies
+          trace: collect_build_prerequisites: begin bus/1.0.0
+          %.*
+          trace: collect_build: add libbaz/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency libbaz/1.0.0 of dependent bus/1.0.0
+          trace: postponed_configurations::add: create {bus | libbaz->{bus/1,1}}
+          trace: collect_build_prerequisites: postpone bus/1.0.0
+          trace: collect_build_postponed (4): recursively collect cfg-negotiated dependents
+          trace: collect_build_postponed (4): select cfg-negotiated dependency alternative for dependent bas/1.0.0
+          trace: collect_build_prerequisites: resume bas/1.0.0
+          trace: collect_build_prerequisites: end bas/1.0.0
+          trace: collect_build_postponed (4): cfg-negotiate end {bas | bus->{bas/2,1}}!
+          trace: collect_build_postponed (5): begin {bus | libbaz->{bus/1,1}}
+          %.*
+          trace: collect_build_postponed (5): cfg-negotiate begin {bus | libbaz->{bus/1,1}}
+          %.*
+          trace: collect_build_postponed (5): recursively collect cfg-negotiated dependencies
+          trace: collect_build_prerequisites: begin libbaz/1.0.0
+          trace: collect_build_prerequisites: end libbaz/1.0.0
+          trace: collect_build_postponed (5): recursively collect cfg-negotiated dependents
+          trace: collect_build_postponed (5): select cfg-negotiated dependency alternative for dependent bus/1.0.0
+          trace: collect_build_prerequisites: resume bus/1.0.0
+          %.*
+          trace: collect_build: add foo/1.0.0
+          trace: collect_build_prerequisites: cfg-postpone dependency foo/1.0.0 of dependent bus/1.0.0
+          trace: postponed_configurations::add: create {bus | foo->{bus/2,1}}
+          trace: collect_build_prerequisites: postpone bus/1.0.0
+          trace: collect_build_postponed (5): cfg-negotiate end {bus | libbaz->{bus/1,1}}!
+          trace: collect_build_postponed (6): begin {bus | foo->{bus/2,1}}
+          %.*
+          trace: collect_build_postponed (6): cfg-negotiate begin {bus | foo->{bus/2,1}}
+          %.*
+          trace: collect_build_postponed (6): recursively collect cfg-negotiated dependencies
+          trace: collect_build_prerequisites: begin foo/1.0.0
+          %.*
+          trace: collect_build_prerequisites: cfg-postpone dependency libfoo/1.0.0 of dependent foo/1.0.0
+          trace: postponed_configurations::add: add {foo 1,1: libfoo} to {bax buc | libfoo->{bax/1,1 buc/1,1}}!
+          trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent foo/1.0.0 is negotiated
+          trace: collect_build_prerequisites: dependency libfoo/1.0.0 of dependent foo/1.0.0 is already (being) recursively collected, skipping
+          trace: collect_build_prerequisites: end foo/1.0.0
+          trace: collect_build_postponed (6): recursively collect cfg-negotiated dependents
+          trace: collect_build_postponed (6): select cfg-negotiated dependency alternative for dependent bus/1.0.0
+          trace: collect_build_prerequisites: resume bus/1.0.0
+          trace: collect_build_prerequisites: end bus/1.0.0
+          trace: collect_build_postponed (6): cfg-negotiate end {bus | foo->{bus/2,1}}!
+          trace: collect_build_postponed (6): end {bus | foo->{bus/2,1}}
+          trace: collect_build_postponed (5): end {bus | libbaz->{bus/1,1}}
+          trace: collect_build_postponed (4): end {bas | bus->{bas/2,1}}
+          trace: collect_build_postponed (3): end {buc buz | bux->{buc/2,1 buz/1,1}}
+          trace: collect_build_postponed (2): end {bax buc | libfoo->{bax/1,1 buc/1,1}}
+          trace: collect_build_postponed (1): end {bas bix | libbar->{bas/1,1 bix/1,1} bar->{bix/1,1}}
+          trace: collect_build_postponed (0): end
+          trace: execute_plan: simulate: yes
+          %.*
+          build plan:
+            new libbaz/1.0.0 (required by bus)
+              config.libbaz.extras=true (set by bus)
+            new libbox/1.0.0 (required by bax)
+              config.libbox.extras=true (set by bax)
+            new libfoo/1.0.0 (required by bax, buc, foo)
+              config.libfoo.extras=true (set by bax)
+            new foo/1.0.0 (required by bus)
+              config.foo.extras=true (set by bus)
+            new bus/1.0.0 (required by bas)
+              config.bus.extras=true (set by bas)
+            new libbar/1.0.0 (required by bar, bas, bax, bix, bux)
+              config.libbar.extras=true (set by bas)
+            new bas/1.0.0
+            new bax/1.0.0
+            new bar/1.0.0 (required by bix)
+              config.bar.extras=true (set by bix)
+            new bux/1.0.0 (required by bix, buc, buz)
+              config.bux.extras=true (set by buc)
+            new bix/1.0.0
+            new buz/1.0.0
+            new buc/1.0.0
+          trace: execute_plan: simulate: no
+          %.*
+          EOE
+
+        $pkg_status -r >>EOO;
+          !bas configured 1.0.0
+            bus configured 1.0.0
+              foo configured 1.0.0
+                libfoo configured 1.0.0
+              libbaz configured 1.0.0
+            libbar configured 1.0.0
+          !bax configured 1.0.0
+            libbar configured 1.0.0
+            libbox configured 1.0.0
+            libfoo configured 1.0.0
+          !bix configured 1.0.0
+            bar configured 1.0.0
+              libbar configured 1.0.0
+            bux configured 1.0.0
+              libbar configured 1.0.0
+            libbar configured 1.0.0
+          !buz configured 1.0.0
+            bux configured 1.0.0
+              libbar configured 1.0.0
+          !buc configured 1.0.0
+            bux configured 1.0.0
+              libbar configured 1.0.0
+            libfoo configured 1.0.0
+          EOO
+
+        $pkg_drop bas bax bix buz buc
+      }
+
       : up-negotiate-dependency
       :
       {