concretizer: move dump logic into solver.asp

- moving the dump logic into spack.solver.asp.solve() allows us to print
  out useful debug info sooner

- prior approach required a successful solve to print out anyhting.

lib/spack/spack/cmd/solve.py

@@ -93,24 +93,6 @@ def solve(parser, args):
     if not result.satisfiable:
         tty.die("Unsatisfiable spec.")
 
-    # dump generated ASP program
-    if 'asp' in dump:
-        tty.msg('ASP program:')
-        sys.stdout.write(result.asp)
-
-    # dump any warnings generated by the solver
-    if 'warnings' in dump:
-        if result.warnings:
-            tty.msg('Clingo gave the following warnings:')
-            sys.stdout.write(result.warnings)
-        else:
-            tty.msg('No warnings.')
-
-    # dump the raw output of the solver
-    if 'output' in dump:
-        tty.msg('Clingo output:')
-        sys.stdout.write(result.output)
-
     # dump the solutions as concretized specs
     if 'solutions' in dump:
         for i, answer in enumerate(result.answers):

lib/spack/spack/solver/asp.py

@@ -7,6 +7,7 @@
 
 import collections
 import re
+import sys
 import tempfile
 import types
 from six import string_types
@@ -259,6 +260,10 @@ def spec_rules(self, spec):
         self.fact(fn.arch_os(spec.name, arch.os))
         self.fact(fn.arch_target(spec.name, arch.target))
 
+        # variants
+        for vname, variant in spec.variants.items():
+            self.fact(fn.variant_value(spec.name, vname, variant.value))
+
         # TODO
         # dependencies
         # compiler
@@ -403,6 +408,10 @@ def solve(specs, dump=None, models=1):
         result = Result(program.read())
         program.seek(0)
 
+        if 'asp' in dump:
+            tty.msg('ASP program:')
+            sys.stdout.write(result.asp)
+
         with tempfile.TemporaryFile("w+") as output:
             with tempfile.TemporaryFile() as warnings:
                 clingo(
@@ -412,13 +421,26 @@ def solve(specs, dump=None, models=1):
                     error=warnings,
                     fail_on_error=False)
 
+                warnings.seek(0)
+                result.warnings = warnings.read()
+
+                # dump any warnings generated by the solver
+                if 'warnings' in dump:
+                    if result.warnings:
+                        tty.msg('Clingo gave the following warnings:')
+                        sys.stdout.write(result.warnings)
+                    else:
+                        tty.msg('No warnings.')
+
                 output.seek(0)
                 result.output = output.read()
 
+                # dump the raw output of the solver
+                if 'output' in dump:
+                    tty.msg('Clingo output:')
+                    sys.stdout.write(result.output)
+
                 output.seek(0)
                 parser.parse(output, result)
 
-                warnings.seek(0)
-                result.warnings = warnings.read()
-
     return result