concretizer: add error messages and simplify asp.py

2 files changed, 18 insertions, 8 deletions

diff --git a/lib/spack/spack/solver/asp.py b/lib/spack/spack/solver/asp.py
index b7733defb6..4a8a3fbbc5 100644
--- a/lib/spack/spack/solver/asp.py
+++ b/lib/spack/spack/solver/asp.py
@@ -1302,11 +1302,13 @@ class SpackSolverSetup(object):
         platform = spack.platforms.host()
 
         # create set of OS's to consider
-        buildable = set([
-            platform.front_os, platform.back_os, platform.default_os])
+        buildable = set(platform.operating_sys.keys())
+
+        # Consider any OS's mentioned on the command line. We need this to
+        # cross-concretize in CI, and for some tests.
+        # TODO: OS should really be more than just a label -- rework this.
         for spec in specs:
             if spec.architecture and spec.architecture.os:
-                # TODO: does this make sense?
                 buildable.add(spec.architecture.os)
 
         # make directives for buildable OS's
@@ -1585,7 +1587,8 @@ class SpackSolverSetup(object):
             self.gen.newline()
 
             # add OS to possible OS's
-            self.possible_oses.add(spec.os)
+            for dep in spec.traverse():
+                self.possible_oses.add(dep.os)
 
             # add the hash to the one seen so far
             self.seen_hashes.add(h)
@@ -1764,6 +1767,8 @@ class SpecBuilder(object):
             assert concrete_spec, "Unable to look up concrete spec with hash %s" % h
             self._specs[pkg] = concrete_spec
         else:
+            # TODO: remove this code -- it's dead unless we decide that node() clauses
+            # should come before hashes.
             # ensure that if it's already there, it's correct
             spec = self._specs[pkg]
             assert spec.dag_hash() == h
diff --git a/lib/spack/spack/solver/concretize.lp b/lib/spack/spack/solver/concretize.lp
index ad92cd1e62..99ab8a0e00 100644
--- a/lib/spack/spack/solver/concretize.lp
+++ b/lib/spack/spack/solver/concretize.lp
@@ -541,17 +541,20 @@ node_platform_set(Package) :- node_platform_set(Package, _).
 os(OS) :- os(OS, _).
 
 % one os per node
-1 { node_os(Package, OS) : os(OS) } 1 :- node(Package), error("Each node must have exactly one OS").
+1 { node_os(Package, OS) : os(OS) } 1 :-
+   node(Package), error("Each node must have exactly one OS").
 
 % can't have a non-buildable OS on a node we need to build
-:- build(Package), node_os(Package, OS), not buildable_os(OS).
+:- build(Package), node_os(Package, OS), not buildable_os(OS),
+   error("No available OS can be built for").
 
 % can't have dependencies on incompatible OS's
 :- depends_on(Package, Dependency),
    node_os(Package, PackageOS),
    node_os(Dependency, DependencyOS),
    not os_compatible(PackageOS, DependencyOS),
-   build(Package).
+   build(Package),
+   error("Dependencies must have compatible OS's with their dependents").
 
 % give OS choice weights according to os declarations
 node_os_weight(Package, Weight)
@@ -641,7 +644,9 @@ node_target_mismatch(Parent, Dependency)
   :- depends_on(Parent, Dependency),
      not node_target_match(Parent, Dependency).
 
-:- node(Package), node_target(Package, Target), not target(Target).
+% disallow reusing concrete specs that don't have a compatible target
+:- node(Package), node_target(Package, Target), not target(Target),
+   error("No satisfying package's target is compatible with this machine").
 
 #defined node_target_set/2.
 #defined package_target_weight/3.