Invert and rename the nobuild option in package.yaml configs to buildable.

lib/spack/docs/site_configuration.rst

@@ -78,8 +78,7 @@ This example lists three installations of OpenMPI, one built with gcc,
 one built with gcc and debug information, and another built with Intel.
 If Spack is asked to build a package that uses one of these MPIs as a
 dependency, it will use the the pre-installed OpenMPI in
-the given directory.  This example also specifies that Spack should never
-build its own OpenMPI via the ``nobuild: True`` option.
+the given directory.  
 
 Each ``packages.yaml`` begins with a ``packages:`` token, followed
 by a list of package names.  To specify externals, add a ``paths``
@@ -111,16 +110,16 @@ be:
       paths:
         openmpi@1.4.3%gcc@4.4.7=chaos_5_x86_64_ib: /opt/openmpi-1.4.3
         openmpi@1.4.3%gcc@4.4.7=chaos_5_x86_64_ib+debug: /opt/openmpi-1.4.3-debug
-        openmpi@1.6.5%intel@10.1=chaos_5_x86_64_ib: /opt/openmpi-1.6.5-intel
-      nobuild: True
+        openmpi@1.6.5%intel@10.1=chaos_5_x86_64_ib: /opt/openmpi-1.6.5-intel                
+      buildable: False
 
-The addition of the ``nobuild`` flag tells Spack that it should never build
+The addition of the ``buildable`` flag tells Spack that it should never build
 its own version of OpenMPI, and it will instead always rely on a pre-built
-OpenMPI.  Similar to ``paths``, ``nobuild`` is specified as a property under
+OpenMPI.  Similar to ``paths``, ``buildable`` is specified as a property under
 a package name.
 
-The ``nobuild`` does not need to be paired with external packages.
-It could also be used alone to forbid packages that may be
+The ``buildable`` does not need to be paired with external packages.  
+It could also be used alone to forbid packages that may be 
 buggy or otherwise undesirable.
 
 

lib/spack/spack/concretize.py

@@ -69,12 +69,12 @@ def _valid_virtuals_and_externals(self, spec):
             packages = [spec]
 
         # For each candidate package, if it has externals add those to the candidates
-        # if it's a nobuild, then only add the externals.
+        # if it's not buildable, then only add the externals.
         candidates = []
         all_compilers = spack.compilers.all_compilers()
         for pkg in packages:
             externals = spec_externals(pkg)
-            buildable = not is_spec_nobuild(pkg)
+            buildable = is_spec_buildable(pkg)
             if buildable:
                 candidates.append((pkg, None))
             for ext in externals:
@@ -369,8 +369,8 @@ def __init__(self, spec):
 
 
 class NoBuildError(spack.error.SpackError):
-    """Raised when a package is configured with the nobuild option, but
+    """Raised when a package is configured with the buildable option False, but
        no satisfactory external versions can be found"""
     def __init__(self, spec):
         super(NoBuildError, self).__init__(
-            "The spec '%s' is configured as nobuild, and no matching external installs were found" % spec.name)
+            "The spec '%s' is configured as not buildable, and no matching external installs were found" % spec.name)

lib/spack/spack/config.py

@@ -220,9 +220,9 @@
                                 'type' : 'array',
                                 'default' : [],
                                 'items' : { 'type' : 'string' } }, #compiler specs
-                            'nobuild': {
+                            'buildable': {
                                 'type':  'boolean',
-                                'default': False,
+                                'default': True,
                              },
                             'providers': {
                                 'type':  'object',
@@ -557,15 +557,15 @@ def spec_externals(spec):
     return spec_locations
 
 
-def is_spec_nobuild(spec):
-    """Return true if the spec pkgspec is configured as nobuild"""
+def is_spec_buildable(spec):
+    """Return true if the spec pkgspec is configured as buildable"""
     allpkgs = get_config('packages')
     name = spec.name
     if not spec.name in allpkgs:
-        return False
-    if not 'nobuild' in allpkgs[spec.name]:
-        return False
-    return allpkgs[spec.name]['nobuild']
+        return True
+    if not 'buildable' in allpkgs[spec.name]:
+        return True
+    return allpkgs[spec.name]['buildable']
 
 
 class ConfigError(SpackError): pass

lib/spack/spack/test/mock_packages_test.py

@@ -52,11 +52,11 @@
 mock_packages_config = """\
 packages:
   externaltool:
-    nobuild: True
+    buildable: False
     paths:
       externaltool@1.0%gcc@4.5.0: /path/to/external_tool
   externalvirtual:
-    nobuild: True
+    buildable: False
     paths:
       externalvirtual@2.0%clang@3.3: /path/to/external_virtual_clang
       externalvirtual@1.0%gcc@4.5.0: /path/to/external_virtual_gcc