solver: add messages to conditions for conflict triggers/constraints

lib/spack/spack/solver/asp.py

@@ -761,13 +761,18 @@ def target_ranges(self, spec, single_target_fn):
     def conflict_rules(self, pkg):
         default_msg = "{0} conflicts for '{1}' and '{2}'"
         for trigger, constraints in pkg.conflicts.items():
-            trigger_id = self.condition(spack.spec.Spec(trigger), name=pkg.name)
+            trigger_msg = "conflict trigger %s" % str(trigger)
+            trigger_id = self.condition(
+                spack.spec.Spec(trigger), name=pkg.name, msg=trigger_msg)
 
-            for constraint, msg in constraints:
-                if msg is None:
-                    msg = default_msg.format(pkg.name, trigger, constraint)
-                constraint_id = self.condition(constraint, name=pkg.name)
-                self.gen.fact(fn.conflict(pkg.name, trigger_id, constraint_id, msg))
+            for constraint, conflict_msg in constraints:
+                if conflict_msg is None:
+                    conflict_msg = default_msg.format(pkg.name, trigger, constraint)
+                constraint_msg = "conflict constraint %s" % str(constraint)
+                constraint_id = self.condition(
+                    constraint, name=pkg.name, msg=constraint_msg)
+                self.gen.fact(
+                    fn.conflict(pkg.name, trigger_id, constraint_id, conflict_msg))
                 self.gen.newline()
 
     def available_compilers(self):
@@ -924,7 +929,7 @@ def pkg_rules(self, pkg, tests):
             )
         )
 
-    def condition(self, required_spec, imposed_spec=None, name=None):
+    def condition(self, required_spec, imposed_spec=None, name=None, msg=None):
         """Generate facts for a dependency or virtual provider condition.
 
         Arguments:
@@ -933,7 +938,7 @@ def condition(self, required_spec, imposed_spec=None, name=None):
                 are imposed when this condition is triggered
             name (str or None): name for `required_spec` (required if
                 required_spec is anonymous, ignored if not)
-
+            msg (str or None): description of the condition
         Returns:
             int: id of the condition created by this function
         """
@@ -942,7 +947,7 @@ def condition(self, required_spec, imposed_spec=None, name=None):
         assert named_cond.name, "must provide name for anonymous condtions!"
 
         condition_id = next(self._condition_id_counter)
-        self.gen.fact(fn.condition(condition_id))
+        self.gen.fact(fn.condition(condition_id, msg))
 
         # requirements trigger the condition
         requirements = self.spec_clauses(

lib/spack/spack/solver/concretize.lp

@@ -87,7 +87,7 @@ node_version_satisfies(Package, Constraint)
 % conditions are specified with `condition_requirement` and hold when
 % corresponding spec attributes hold.
 condition_holds(ID) :-
-  condition(ID);
+  condition(ID, _);
   attr(Name, A1)         : condition_requirement(ID, Name, A1);
   attr(Name, A1, A2)     : condition_requirement(ID, Name, A1, A2);
   attr(Name, A1, A2, A3) : condition_requirement(ID, Name, A1, A2, A3).
@@ -106,7 +106,7 @@ attr(Name, A1, A2, A3) :- impose(ID), imposed_constraint(ID, Name, A1, A2, A3).
    variant_value(Package, Variant, Value),
    not imposed_constraint(Hash, "variant_value", Package, Variant, Value).
 
-#defined condition/1.
+#defined condition/2.
 #defined condition_requirement/3.
 #defined condition_requirement/4.
 #defined condition_requirement/5.