Initial ability to swap compilers.

Fixes SPACK-16 and forces compiler script to build using compiler wrappers.

- works with gcc and clang on laptop.

19 files changed, 231 insertions, 118 deletions

diff --git a/bin/spack b/bin/spack
index fb9f045f35..fef793a6ce 100755
--- a/bin/spack
+++ b/bin/spack
@@ -41,7 +41,7 @@ sys.path.insert(0, SPACK_LIB_PATH)
 
 # If there is no working directory, use the spack prefix.
 try:
-    os.getcwd()
+    working_dir = os.getcwd()
 except OSError:
     os.chdir(SPACK_PREFIX)
 
@@ -79,6 +79,7 @@ args = parser.parse_args()
 # Set up environment based on args.
 spack.verbose = args.verbose
 spack.debug = args.debug
+spack.spack_working_dir = working_dir
 if args.mock:
     from spack.packages import PackageDB
     spack.db = PackageDB(spack.mock_packages_path)
diff --git a/lib/spack/env/cc b/lib/spack/env/cc
index e5dbf21beb..09abf3a31d 100755
--- a/lib/spack/env/cc
+++ b/lib/spack/env/cc
@@ -10,7 +10,7 @@ import argparse
 from contextlib import closing
 
 # Import spack parameters through the build environment.
-spack_lib      = os.environ.get("SPACK_LIB")
+spack_lib = os.environ.get("SPACK_LIB")
 if not spack_lib:
     print "Spack compiler must be run from spack!"
     sys.exit(1)
@@ -20,24 +20,23 @@ sys.path.append(spack_lib)
 from spack.compilation import *
 import llnl.util.tty as tty
 
-spack_prefix     = get_env_var("SPACK_PREFIX")
-spack_build_root = get_env_var("SPACK_BUILD_ROOT")
-spack_debug      = get_env_flag("SPACK_DEBUG")
-spack_deps       = get_path("SPACK_DEPENDENCIES")
-spack_env_path   = get_path("SPACK_ENV_PATH")
+spack_prefix        = get_env_var("SPACK_PREFIX")
+spack_debug         = get_env_flag("SPACK_DEBUG")
+spack_deps          = get_path("SPACK_DEPENDENCIES")
+spack_env_path      = get_path("SPACK_ENV_PATH")
+spack_debug_log_dir = get_env_var("SPACK_DEBUG_LOG_DIR")
+spack_spec          = get_env_var("SPACK_SPEC")
+
+spack_cc  = get_env_var("SPACK_CC")
+spack_cxx = get_env_var("SPACK_CXX")
+spack_f77 = get_env_var("SPACK_F77")
+spack_fc  = get_env_var("SPACK_FC")
 
 # Figure out what type of operation we're doing
 command = os.path.basename(sys.argv[0])
 
 cpp, cc, ccld, ld, version_check = range(5)
 
-########################################################################
-# TODO: this can to be removed once JIRA issue SPACK-16 is resolved
-#
-if command == 'CC':
-    command = 'c++'
-########################################################################
-
 if command == 'cpp':
     mode = cpp
 elif command == 'ld':
@@ -49,7 +48,23 @@ elif '-c' in sys.argv:
 else:
     mode = ccld
 
-if '-V' in sys.argv or '-v' in sys.argv or '--version' in sys.argv:
+
+if command in ('cc', 'gcc', 'c89', 'c99', 'clang'):
+    command = spack_cc
+elif command in ('c++', 'CC', 'g++', 'clang++'):
+    command = spack_cxx
+elif command in ('f77'):
+    command = spack_f77
+elif command in ('fc'):
+    command = spack_fc
+elif command in ('ld', 'cpp'):
+    pass # leave it the same.  TODO: what's the right thing?
+else:
+    raise Exception("Unknown compiler: %s" % command)
+
+
+version_args = ['-V', '-v', '--version', '-dumpversion']
+if any(arg in sys.argv for arg in version_args):
     mode = version_check
 
 # Parse out the includes, libs, etc. so we can adjust them if need be.
@@ -104,8 +119,8 @@ os.environ["PATH"] = ":".join(path)
 full_command = [command] + arguments
 
 if spack_debug:
-    input_log = os.path.join(spack_build_root, 'spack_cc_in.log')
-    output_log = os.path.join(spack_build_root, 'spack_cc_out.log')
+    input_log = os.path.join(spack_debug_log_dir,  'spack-cc-%s.in.log' % spack_spec)
+    output_log = os.path.join(spack_debug_log_dir, 'spack-cc-%s.out.log' % spack_spec)
     with closing(open(input_log, 'a')) as log:
         args = [os.path.basename(sys.argv[0])] + sys.argv[1:]
         log.write("%s\n" % " ".join(arg.replace(' ', r'\ ') for arg in args))
diff --git a/lib/spack/spack/build_environment.py b/lib/spack/spack/build_environment.py
index 8d3d0909db..36dae74e84 100644
--- a/lib/spack/spack/build_environment.py
+++ b/lib/spack/spack/build_environment.py
@@ -34,7 +34,7 @@ import platform
 from llnl.util.filesystem import *
 
 import spack
-from spack.compilers import compiler_for_spec
+import spack.compilers as compilers
 from spack.util.executable import Executable, which
 from spack.util.environment import *
 
@@ -52,7 +52,9 @@ SPACK_LIB              = 'SPACK_LIB'
 SPACK_ENV_PATH         = 'SPACK_ENV_PATH'
 SPACK_DEPENDENCIES     = 'SPACK_DEPENDENCIES'
 SPACK_PREFIX           = 'SPACK_PREFIX'
-SPACK_BUILD_ROOT       = 'SPACK_BUILD_ROOT'
+SPACK_DEBUG            = 'SPACK_DEBUG'
+SPACK_SPEC             = 'SPACK_SPEC'
+SPACK_DEBUG_LOG_DIR    = 'SPACK_DEBUG_LOG_DIR'
 
 
 class MakeExecutable(Executable):
@@ -82,7 +84,19 @@ class MakeExecutable(Executable):
 
 def set_compiler_environment_variables(pkg):
     assert(pkg.spec.concrete)
-    compiler = compiler_for_spec(pkg.spec.compiler)
+    compiler = compilers.compiler_for_spec(pkg.spec.compiler)
+
+    # Set compiler variables used by CMake and autotools
+    os.environ['CC']  = 'cc'
+    os.environ['CXX'] = 'c++'
+    os.environ['F77'] = 'f77'
+    os.environ['FC']  = 'fc'
+
+    # Set SPACK compiler variables so that our wrapper knows what to call
+    os.environ['SPACK_CC']  = compiler.cc.command
+    os.environ['SPACK_CXX'] = compiler.cxx.command
+    os.environ['SPACK_F77'] = compiler.f77.command
+    os.environ['SPACK_FC']  = compiler.fc.command
 
 
 def set_build_environment_variables(pkg):
@@ -108,9 +122,6 @@ def set_build_environment_variables(pkg):
     # Install prefix
     os.environ[SPACK_PREFIX] = pkg.prefix
 
-    # Build root for logging.
-    os.environ[SPACK_BUILD_ROOT] = pkg.stage.expanded_archive_path
-
     # Remove these vars from the environment during build becaus they
     # can affect how some packages find libraries.  We want to make
     # sure that builds never pull in unintended external dependencies.
@@ -120,6 +131,12 @@ def set_build_environment_variables(pkg):
     bin_dirs = ['%s/bin' % prefix for prefix in dep_prefixes]
     path_put_first('PATH', [bin for bin in bin_dirs if os.path.isdir(bin)])
 
+    # Working directory for the spack command itself, for debug logs.
+    if spack.debug:
+        os.environ[SPACK_DEBUG] = "TRUE"
+    os.environ[SPACK_SPEC] = str(pkg.spec)
+    os.environ[SPACK_DEBUG_LOG_DIR] = spack.spack_working_dir
+
 
 def set_module_variables_for_package(pkg):
     """Populate the module scope of install() with some useful functions.
diff --git a/lib/spack/spack/cmd/compilers.py b/lib/spack/spack/cmd/compilers.py
index 8267ecbd6b..c34118f033 100644
--- a/lib/spack/spack/cmd/compilers.py
+++ b/lib/spack/spack/cmd/compilers.py
@@ -34,7 +34,7 @@ description = "List available compilers"
 def compilers(parser, args):
     tty.msg("Available compilers")
 
-    index = index_by(spack.compilers.available_compilers(), 'name')
+    index = index_by(spack.compilers.all_compilers(), 'name')
     for name, compilers in index.items():
         tty.hline(name, char='-', color=spack.spec.compiler_color)
         colify(compilers, indent=4)
diff --git a/lib/spack/spack/cmd/find.py b/lib/spack/spack/cmd/find.py
index eaa3632043..08cfb5af96 100644
--- a/lib/spack/spack/cmd/find.py
+++ b/lib/spack/spack/cmd/find.py
@@ -62,7 +62,7 @@ def find(parser, args):
 
     # Make a dict with specs keyed by architecture and compiler.
     specs = [s for s in spack.db.installed_package_specs()
-             if not query_specs or any(spec.satisfies(q) for q in query_specs)]
+             if not query_specs or any(s.satisfies(q) for q in query_specs)]
     index = index_by(specs, 'architecture', 'compiler')
 
     # Traverse the index and print out each package
diff --git a/lib/spack/spack/cmd/install.py b/lib/spack/spack/cmd/install.py
index ea11cb89a9..4570d6c40f 100644
--- a/lib/spack/spack/cmd/install.py
+++ b/lib/spack/spack/cmd/install.py
@@ -36,7 +36,10 @@ def setup_parser(subparser):
         help="Do not try to install dependencies of requested packages.")
     subparser.add_argument(
         '--keep-prefix', action='store_true', dest='keep_prefix',
-        help="Don't clean up staging area when install completes.")
+        help="Don't remove the install prefix if installation fails.")
+    subparser.add_argument(
+        '--keep-stage', action='store_true', dest='keep_stage',
+        help="Don't remove the build stage if installation succeeds.")
     subparser.add_argument(
         '-n', '--no-checksum', action='store_true', dest='no_checksum',
         help="Do not check packages against checksum")
@@ -55,4 +58,5 @@ def install(parser, args):
     for spec in specs:
         package = spack.db.get(spec)
         package.do_install(keep_prefix=args.keep_prefix,
+                           keep_stage=args.keep_stage,
                            ignore_deps=args.ignore_deps)
diff --git a/lib/spack/spack/cmd/uninstall.py b/lib/spack/spack/cmd/uninstall.py
index df208b3a6a..044a9b2960 100644
--- a/lib/spack/spack/cmd/uninstall.py
+++ b/lib/spack/spack/cmd/uninstall.py
@@ -36,6 +36,11 @@ def setup_parser(subparser):
         '-f', '--force', action='store_true', dest='force',
         help="Remove regardless of whether other packages depend on this one.")
     subparser.add_argument(
+        '-a', '--all', action='store_true', dest='all',
+        help="USE CAREFULLY.  Remove ALL installed packages that match each supplied spec. " +
+        "i.e., if you say uninstall libelf, ALL versions of libelf are uninstalled. " +
+        "This is both useful and dangerous, like rm -r.")
+    subparser.add_argument(
         'packages', nargs=argparse.REMAINDER, help="specs of packages to uninstall")
 
 
@@ -50,15 +55,17 @@ def uninstall(parser, args):
     pkgs = []
     for spec in specs:
         matching_specs = spack.db.get_installed(spec)
-        if len(matching_specs) > 1:
-            tty.die("%s matches multiple packages.  Which one did you mean?"
-                    % spec, *matching_specs)
+        if not args.all and len(matching_specs) > 1:
+            tty.die("%s matches multiple packages." % spec,
+                    "You can either:",
+                    " a) Use spack uninstall -a to uninstall ALL matching specs, or",
+                    " b) use a more specific spec.",
+                    "Matching packages:", *("  " + str(s) for s in matching_specs))
 
-        elif len(matching_specs) == 0:
+        if len(matching_specs) == 0:
             tty.die("%s does not match any installed packages." % spec)
 
-        installed_spec = matching_specs[0]
-        pkgs.append(spack.db.get(installed_spec))
+        pkgs.extend(spack.db.get(s) for s in matching_specs)
 
     # Sort packages to be uninstalled by the number of installed dependents
     # This ensures we do things in the right order
diff --git a/lib/spack/spack/compiler.py b/lib/spack/spack/compiler.py
index 27effa20c4..3d097b6180 100644
--- a/lib/spack/spack/compiler.py
+++ b/lib/spack/spack/compiler.py
@@ -16,7 +16,7 @@ def _verify_executables(*paths):
 
 class Compiler(object):
     """This class encapsulates a Spack "compiler", which includes C,
-       C++, Fortran, and F90 compilers.  Subclasses should implement
+       C++, and Fortran compilers.  Subclasses should implement
        support for specific compilers, their possible names, arguments,
        and how to identify the particular type of compiler."""
 
@@ -30,20 +30,20 @@ class Compiler(object):
     f77_names = []
 
     # Subclasses use possible names of Fortran 90 compiler
-    f90_names = []
+    fc_names = []
 
     # Names of generic arguments used by this compiler
     arg_version = '-dumpversion'
     arg_rpath   = '-Wl,-rpath,%s'
 
 
-    def __init__(self, cc, cxx, f77, f90):
-        _verify_executables(cc, cxx, f77, f90)
+    def __init__(self, cc, cxx, f77, fc):
+        _verify_executables(cc, cxx, f77, fc)
 
         self.cc  = Executable(cc)
         self.cxx = Executable(cxx)
         self.f77 = Executable(f77)
-        self.f90 = Executable(f90)
+        self.fc  = Executable(fc)
 
     @property
     @memoized
diff --git a/lib/spack/spack/compilers/__init__.py b/lib/spack/spack/compilers/__init__.py
index 095e26edb5..a36ea618bc 100644
--- a/lib/spack/spack/compilers/__init__.py
+++ b/lib/spack/spack/compilers/__init__.py
@@ -41,49 +41,69 @@ _imported_compilers_module = 'spack.compiler.versions'
 _imported_versions_module  = 'spack.compilers'
 
 
+def _auto_compiler_spec(function):
+    def converter(cspec_like):
+        if not isinstance(cspec_like, spack.spec.CompilerSpec):
+            cspec_like = spack.spec.CompilerSpec(cspec_like)
+        return function(cspec_like)
+    return converter
+
+
 @memoized
 def supported_compilers():
-    """Return a list of names of compilers supported by Spack.
+    """Return a set of names of compilers supported by Spack.
 
        See available_compilers() to get a list of all the available
        versions of supported compilers.
     """
-    return sorted(c for c in list_modules(spack.compilers_path))
+    return sorted(name for name in list_modules(spack.compilers_path))
 
 
+@_auto_compiler_spec
 def supported(compiler_spec):
     """Test if a particular compiler is supported."""
-    if not isinstance(compiler_spec, spack.spec.CompilerSpec):
-        compiler_spec = spack.spec.CompilerSpec(compiler_spec)
     return compiler_spec.name in supported_compilers()
 
 
-def available_compilers():
-    """Return a list of specs for all the compiler versions currently
-       available to build with.  These are instances of
-       CompilerSpec.
+@memoized
+def all_compilers():
+    """Return a set of specs for all the compiler versions currently
+       available to build with.  These are instances of CompilerSpec.
     """
-    return [spack.spec.CompilerSpec(c)
-            for c in list_modules(spack.compiler_version_path)]
+    return set(spack.spec.CompilerSpec(c)
+               for c in list_modules(spack.compiler_version_path))
 
 
-def compiler_for_spec(compiler_spec):
-    """This gets an instance of an actual spack.compiler.Compiler object
-       from a compiler spec.  The spec needs to be concrete for this to
-       work; it will raise an error if passed an abstract compiler.
+@_auto_compiler_spec
+def find(compiler_spec):
+    """Return specs of available compilers that match the supplied
+       compiler spec.  Return an list if nothing found."""
+    return [c for c in all_compilers() if c.satisfies(compiler_spec)]
+
+
+@_auto_compiler_spec
+def compilers_for_spec(compiler_spec):
+    """This gets all compilers that satisfy the supplied CompilerSpec.
+       Returns an empty list if none are found.
     """
-    matches = [c for c in available_compilers() if c.satisfies(compiler_spec)]
+    matches = find(compiler_spec)
 
-    # TODO: do something when there are zero matches.
-    assert(len(matches) >= 1)
+    compilers = []
+    for cspec in matches:
+        path = join_path(spack.compiler_version_path, "%s.py" % cspec)
+        mod  = imp.load_source(_imported_versions_module, path)
+        cls  = class_for_compiler_name(cspec.name)
+        compilers.append(cls(mod.cc, mod.cxx, mod.f77, mod.fc))
 
-    compiler = matches[0]
-    file_path = join_path(spack.compiler_version_path, "%s.py" % compiler)
+    return compilers
 
-    mod = imp.load_source(_imported_versions_module, file_path)
-    compiler_class = class_for_compiler_name(compiler.name)
 
-    return compiler_class(mod.cc, mod.cxx, mod.f77, mod.f90)
+@_auto_compiler_spec
+def compiler_for_spec(compiler_spec):
+    assert(compiler_spec.concrete)
+    compilers = compilers_for_spec(compiler_spec)
+    assert(len(compilers) == 1)
+    return compilers[0]
 
 
 def class_for_compiler_name(compiler_name):
diff --git a/lib/spack/spack/compilers/clang.py b/lib/spack/spack/compilers/clang.py
index 9ed7b57846..1616fcaf08 100644
--- a/lib/spack/spack/compilers/clang.py
+++ b/lib/spack/spack/compilers/clang.py
@@ -35,7 +35,7 @@ class Clang(Compiler):
     f77_names = []
 
     # Subclasses use possible names of Fortran 90 compiler
-    f90_names = []
+    fc_names = []
 
-    def __init__(self, cc, cxx, f77, f90):
-        super(Gcc, self).__init__(cc, cxx, f77, f90)
+    def __init__(self, cc, cxx, f77, fc):
+        super(Clang, self).__init__(cc, cxx, f77, fc)
diff --git a/lib/spack/spack/compilers/gcc.py b/lib/spack/spack/compilers/gcc.py
index 638051008f..f73cb08c63 100644
--- a/lib/spack/spack/compilers/gcc.py
+++ b/lib/spack/spack/compilers/gcc.py
@@ -35,7 +35,7 @@ class Gcc(Compiler):
     f77_names = ['gfortran']
 
     # Subclasses use possible names of Fortran 90 compiler
-    f90_names = ['gfortran']
+    fc_names = ['gfortran']
 
-    def __init__(self, cc, cxx, f77, f90):
-        super(Gcc, self).__init__(cc, cxx, f77, f90)
+    def __init__(self, cc, cxx, f77, fc):
+        super(Gcc, self).__init__(cc, cxx, f77, fc)
diff --git a/lib/spack/spack/compilers/intel.py b/lib/spack/spack/compilers/intel.py
index ebbab57ed1..fe2aabd864 100644
--- a/lib/spack/spack/compilers/intel.py
+++ b/lib/spack/spack/compilers/intel.py
@@ -35,7 +35,7 @@ class Intel(Compiler):
     f77_names = ['ifort']
 
     # Subclasses use possible names of Fortran 90 compiler
-    f90_names = ['ifort']
+    fc_names = ['ifort']
 
-    def __init__(self, cc, cxx, f77, f90):
-        super(Gcc, self).__init__(cc, cxx, f77, f90)
+    def __init__(self, cc, cxx, f77, fc):
+        super(Intel, self).__init__(cc, cxx, f77, fc)
diff --git a/lib/spack/spack/concretize.py b/lib/spack/spack/concretize.py
index 28efcaea64..312b9ce1b1 100644
--- a/lib/spack/spack/concretize.py
+++ b/lib/spack/spack/concretize.py
@@ -33,9 +33,10 @@ or user preferences.
 TODO: make this customizable and allow users to configure
       concretization  policies.
 """
-import spack.architecture
-import spack.compilers
 import spack.spec
+import spack.compilers
+import spack.architecture
+import spack.error
 from spack.version import *
 
 
@@ -117,9 +118,13 @@ class DefaultConcretizer(object):
                            if p.compiler is not None).compiler
 
             if not nearest.concrete:
-                matches = [c for c in spack.compilers.available_compilers()
-                           if c.name == nearest.name]
-                nearest.versions = sorted(matches)[-1].versions.copy()
+                # Take the newest compiler that saisfies the spec
+                matches = sorted(spack.compilers.find(nearest))
+                if not matches:
+                    raise UnavailableCompilerVersionError(nearest)
+
+                # copy concrete version into nearest spec
+                nearest.versions = matches[-1].versions.copy()
                 assert(nearest.concrete)
 
             spec.compiler = nearest.copy()
@@ -140,3 +145,12 @@ class DefaultConcretizer(object):
         first_key = sorted(index.keys())[0]
         latest_version = sorted(index[first_key])[-1]
         return latest_version
+
+
+class UnavailableCompilerVersionError(spack.error.SpackError):
+    """Raised when there is no available compiler that satisfies a
+       compiler spec."""
+    def __init__(self, compiler_spec):
+        super(UnavailableCompilerVersionError, self).__init__(
+            "No available compiler version matches '%s'" % compiler_spec,
+            "Run 'spack compilers' to see available compiler Options.")
diff --git a/lib/spack/spack/package.py b/lib/spack/spack/package.py
index b40448df37..069c66f4a7 100644
--- a/lib/spack/spack/package.py
+++ b/lib/spack/spack/package.py
@@ -626,6 +626,7 @@ class Package(object):
         """
         # whether to keep the prefix on failure.  Default is to destroy it.
         keep_prefix = kwargs.get('keep_prefix', False)
+        keep_stage  = kwargs.get('keep_stage', False)
         ignore_deps = kwargs.get('ignore_deps', False)
 
         if not self.spec.concrete:
@@ -671,9 +672,10 @@ class Package(object):
                         "Install failed for %s.  Nothing was installed!"
                         % self.name)
 
-                # On successful install, remove the stage.
-                # Leave if there is an error
-                self.stage.destroy()
+                if not keep_stage:
+                    # On successful install, remove the stage.
+                    # Leave it if there is an error
+                    self.stage.destroy()
 
                 tty.msg("Successfully installed %s" % self.name)
                 print_pkg(self.prefix)
@@ -725,16 +727,16 @@ class Package(object):
         force = kwargs.get('force', False)
 
         if not self.installed:
-            raise InstallError(self.name + " is not installed.")
+            raise InstallError(self.spec + " is not installed.")
 
         if not force:
             deps = self.installed_dependents
             if deps: raise InstallError(
                 "Cannot uninstall %s. The following installed packages depend on it: %s"
-                % (self.name, deps))
+                % (self.spec, deps))
 
         self.remove_prefix()
-        tty.msg("Successfully uninstalled %s." % self.name)
+        tty.msg("Successfully uninstalled %s." % self.spec)
 
 
     def do_clean(self):
diff --git a/lib/spack/spack/spec.py b/lib/spack/spack/spec.py
index 35a17621b6..5848ac2000 100644
--- a/lib/spack/spack/spec.py
+++ b/lib/spack/spack/spec.py
@@ -102,7 +102,7 @@ from llnl.util.tty.color import *
 import spack
 import spack.parse
 import spack.error
-from spack.compilers import supported as supported_compiler
+import spack.compilers as compilers
 
 from spack.version import *
 from spack.util.string import *
@@ -231,8 +231,9 @@ class CompilerSpec(object):
 
     @property
     def concrete(self):
-        """A CompilerSpec is concrete if its versions are concrete."""
-        return self.versions.concrete
+        """A CompilerSpec is concrete if its versions are concrete and there
+           is an available compiler with the right version."""
+        return self.versions.concrete and self in compilers.all_compilers()
 
 
     @property
@@ -260,6 +261,9 @@ class CompilerSpec(object):
             out += "@%s" % vlist
         return out
 
+    def __repr__(self):
+        return str(self)
+
 
 @key_ordering
 class Variant(object):
@@ -821,12 +825,13 @@ class Spec(object):
 
             # validate compiler in addition to the package name.
             if spec.compiler:
-                if not supported_compiler(spec.compiler):
+                if not compilers.supported(spec.compiler):
                     raise UnsupportedCompilerError(spec.compiler.name)
 
 
     def constrain(self, other, **kwargs):
         other = self._autospec(other)
+        constrain_deps = kwargs.get('deps', True)
 
         if not self.name == other.name:
             raise UnsatisfiableSpecNameError(self.name, other.name)
@@ -854,7 +859,7 @@ class Spec(object):
         self.variants.update(other.variants)
         self.architecture = self.architecture or other.architecture
 
-        if kwargs.get('deps', True):
+        if constrain_deps:
             self._constrain_dependencies(other)
 
 
@@ -911,28 +916,28 @@ class Spec(object):
 
     def satisfies(self, other, **kwargs):
         other = self._autospec(other)
+        satisfy_deps = kwargs.get('deps', True)
 
         # First thing we care about is whether the name matches
         if self.name != other.name:
             return False
 
-        # This function simplifies null checking below
-        def check(attribute, op):
-            s = getattr(self, attribute)
-            o = getattr(other, attribute)
-            return not s or not o or op(s,o)
-
-        # All these attrs have satisfies criteria of their own
-        for attr in ('versions', 'variants', 'compiler'):
-            if not check(attr, lambda s, o: s.satisfies(o)):
+        # All these attrs have satisfies criteria of their own,
+        # but can be None to indicate no constraints.
+        for s, o in ((self.versions, other.versions),
+                     (self.variants, other.variants),
+                     (self.compiler, other.compiler)):
+            if s and o and not s.satisfies(o):
                 return False
 
-        # Architecture is just a string
-        # TODO: inviestigate making an Architecture class for symmetry
-        if not check('architecture', lambda s,o: s == o):
+        # Architecture satisfaction is currently just string equality.
+        # Can be None for unconstrained, though.
+        if (self.architecture and other.architecture and
+            self.architecture != other.architecture):
             return False
 
-        if kwargs.get('deps', True):
+        # If we need to descend into dependencies, do it, otherwise we're done.
+        if satisfy_deps:
             return self.satisfies_dependencies(other)
         else:
             return True
diff --git a/lib/spack/spack/test/spec_semantics.py b/lib/spack/spack/test/spec_semantics.py
index dbd04f9449..5fb09e68af 100644
--- a/lib/spack/spack/test/spec_semantics.py
+++ b/lib/spack/spack/test/spec_semantics.py
@@ -37,16 +37,13 @@ class SpecSematicsTest(MockPackagesTest):
         left = Spec(spec)
         right = parse_anonymous_spec(anon_spec, left.name)
 
+        # Satisfies is one-directional.
         self.assertTrue(left.satisfies(right))
         self.assertTrue(left.satisfies(anon_spec))
-        self.assertTrue(right.satisfies(left))
 
-        try:
-            left.copy().constrain(right)
-            left.copy().constrain(anon_spec)
-            right.copy().constrain(left)
-        except SpecError, e:
-            self.fail("Got a SpecError in constrain!  " + e.message)
+        # if left satisfies right, then we should be able to consrain
+        # right by left.  Reverse is not always true.
+        right.copy().constrain(left)
 
 
     def check_unsatisfiable(self, spec, anon_spec):
@@ -56,25 +53,21 @@ class SpecSematicsTest(MockPackagesTest):
         self.assertFalse(left.satisfies(right))
         self.assertFalse(left.satisfies(anon_spec))
 
-        self.assertFalse(right.satisfies(left))
+        self.assertRaises(UnsatisfiableSpecError, right.copy().constrain, left)
 
-        self.assertRaises(UnsatisfiableSpecError, left.constrain, right)
-        self.assertRaises(UnsatisfiableSpecError, left.constrain, anon_spec)
-        self.assertRaises(UnsatisfiableSpecError, right.constrain, left)
 
-
-    def check_constrain(self, expected, constrained, constraint):
+    def check_constrain(self, expected, spec, constraint):
         exp = Spec(expected)
-        constrained = Spec(constrained)
+        spec = Spec(spec)
         constraint = Spec(constraint)
-        constrained.constrain(constraint)
-        self.assertEqual(exp, constrained)
+        spec.constrain(constraint)
+        self.assertEqual(exp, spec)
 
 
-    def check_invalid_constraint(self, constrained, constraint):
-        constrained = Spec(constrained)
+    def check_invalid_constraint(self, spec, constraint):
+        spec = Spec(spec)
         constraint = Spec(constraint)
-        self.assertRaises(UnsatisfiableSpecError, constrained.constrain, constraint)
+        self.assertRaises(UnsatisfiableSpecError, spec.constrain, constraint)
 
 
     # ================================================================================
@@ -177,3 +170,8 @@ class SpecSematicsTest(MockPackagesTest):
         self.check_invalid_constraint('libelf+debug~foo', 'libelf+debug+foo')
 
         self.check_invalid_constraint('libelf=bgqos_0', 'libelf=x86_54')
+
+
+    def test_compiler_satisfies(self):
+        self.check_satisfies('foo %gcc@4.7.3', '%gcc@4.7')
+        self.check_unsatisfiable('foo %gcc@4.7', '%gcc@4.7.3')
diff --git a/lib/spack/spack/test/versions.py b/lib/spack/spack/test/versions.py
index e272274a4f..454ab36b8a 100644
--- a/lib/spack/spack/test/versions.py
+++ b/lib/spack/spack/test/versions.py
@@ -311,7 +311,7 @@ class VersionsTest(unittest.TestCase):
         self.check_intersection(['0:1'], [':'], ['0:1'])
 
 
-    def test_satisfaction(self):
+    def test_basic_version_satisfaction(self):
         self.assert_satisfies('4.7.3',   '4.7.3')
 
         self.assert_satisfies('4.7.3',   '4.7')
@@ -326,6 +326,22 @@ class VersionsTest(unittest.TestCase):
         self.assert_does_not_satisfy('4.8',   '4.9')
         self.assert_does_not_satisfy('4',     '4.9')
 
+    def test_basic_version_satisfaction_in_lists(self):
+        self.assert_satisfies(['4.7.3'],   ['4.7.3'])
+
+        self.assert_satisfies(['4.7.3'],   ['4.7'])
+        self.assert_satisfies(['4.7.3b2'], ['4.7'])
+        self.assert_satisfies(['4.7b6'],   ['4.7'])
+
+        self.assert_satisfies(['4.7.3'],   ['4'])
+        self.assert_satisfies(['4.7.3b2'], ['4'])
+        self.assert_satisfies(['4.7b6'],   ['4'])
+
+        self.assert_does_not_satisfy(['4.8.0'], ['4.9'])
+        self.assert_does_not_satisfy(['4.8'],   ['4.9'])
+        self.assert_does_not_satisfy(['4'],     ['4.9'])
+
+    def test_version_range_satisfaction(self):
         self.assert_satisfies('4.7b6', '4.3:4.7')
         self.assert_satisfies('4.3.0', '4.3:4.7')
         self.assert_satisfies('4.3.2', '4.3:4.7')
@@ -336,6 +352,18 @@ class VersionsTest(unittest.TestCase):
         self.assert_satisfies('4.7b6',        '4.3:4.7')
         self.assert_does_not_satisfy('4.8.0', '4.3:4.7')
 
+    def test_version_range_satisfaction_in_lists(self):
+        self.assert_satisfies(['4.7b6'], ['4.3:4.7'])
+        self.assert_satisfies(['4.3.0'], ['4.3:4.7'])
+        self.assert_satisfies(['4.3.2'], ['4.3:4.7'])
+
+        self.assert_does_not_satisfy(['4.8.0'], ['4.3:4.7'])
+        self.assert_does_not_satisfy(['4.3'],   ['4.4:4.7'])
+
+        self.assert_satisfies(['4.7b6'],        ['4.3:4.7'])
+        self.assert_does_not_satisfy(['4.8.0'], ['4.3:4.7'])
+
+    def test_satisfaction_with_lists(self):
         self.assert_satisfies('4.7',     '4.3, 4.6, 4.7')
         self.assert_satisfies('4.7.3',   '4.3, 4.6, 4.7')
         self.assert_satisfies('4.6.5',   '4.3, 4.6, 4.7')
diff --git a/lib/spack/spack/util/executable.py b/lib/spack/spack/util/executable.py
index 845d1470e7..6dea46a5c8 100644
--- a/lib/spack/spack/util/executable.py
+++ b/lib/spack/spack/util/executable.py
@@ -43,7 +43,7 @@ class Executable(object):
 
     @property
     def command(self):
-        return self.exe[0]
+        return ' '.join(self.exe)
 
 
     def __call__(self, *args, **kwargs):
diff --git a/var/spack/packages/libdwarf/package.py b/var/spack/packages/libdwarf/package.py
index 657e84705a..000187736c 100644
--- a/var/spack/packages/libdwarf/package.py
+++ b/var/spack/packages/libdwarf/package.py
@@ -39,6 +39,8 @@ class Libdwarf(Package):
 
     depends_on("libelf")
 
+    parallel = False
+
 
     def clean(self):
         for dir in dwarf_dirs: