Changed add_architecture_from_string, it now loops through the string and checks whether each piece of string is a valid platform, operating system and target. If the operating system or target are none it will use the defaults. Updated the documentation for that method. One thing that bothers me is how to account for the multitude of operating systems when cross compiling. If someone wants to compile with another operating system not found on current platform. How can spack check to see if it is valid?

lib/spack/spack/spec.py

@@ -1238,14 +1238,18 @@ def _autospec(self, spec_like):
             return parse_anonymous_spec(spec_like, self.name)
 
     def _is_valid_platform(self, platform, platform_list):
-        if platform in platform_names:
+        if platform in platform_list:
             return True
         return False
 
     def _is_valid_target(self, target, platform):
         if target in platform.targets:
                 return True
-            return False
+        return False
+    def _is_valid_os(self, os_string, platform):
+        if os_string in platform.operating_sys:
+            return True
+        return False
 
     def add_architecture_from_string(self, arch):
         """ The user is able to provide a architecture string of the form
@@ -1254,8 +1258,9 @@ def add_architecture_from_string(self, arch):
             platform, operating system and target processor classes.
             The platform-os-target triplet can be delimited by a '-'. If any
             portion of the architecture triplet is empty, spack will supply
-            the default. If the architecture is blank then defaults will 
-            be provided based off of the platform
+            the default. If the entire architecture field is blank then 
+            defaults will be provided based off of the platform. 
+            This happens in the concretize_architecture method in concretize.py
 
             e.g 
                 =linux-ubuntu10-x84_64    -> (linux, ubuntu10, x86_64)
@@ -1272,27 +1277,38 @@ def add_architecture_from_string(self, arch):
                                               default_os,
                                               x86_64)
         """
+        if arch is None: return
         
         platform_list = spack.architecture.all_platforms()
-        platform_names = [plat.__name__.lower() for plat in platform_list]
-        if arch is None: 
-            return
-        # Get all the platforms to check whether string is valid
-        Arch = namedtuple("Arch", "platform platform_os target")        
+        platform_names = {plat.__name__.lower():plat for plat in platform_list}
+        Arch = spack.architecture.Arch       
         arch_list = arch.split("-")
+        
+        # Create instance of current platform, gets overwritten if user
+        # provided a platform spec.
         platform = spack.architecture.sys_type()                                                 
+        target = None
+        platform_os = None
+
         for entry in arch_list:
-            if _is_valid_platform(entry, platform_names):
-                platform = entry()
-            elif _is_valid_target(entry, platform):
-                target = entry
+            if self._is_valid_platform(entry, platform_names):
+                if entry != platform.name:
+                    platform = platform_dict[entry]() # Create instance of platform
+            elif self._is_valid_target(entry, platform):
+                target = platform.target(entry)
+            # Need to figure out if we're supporting arbitrary os's and how
+            # to account for them
+            # Not really a good implementation since the user can add
+            # gibberish and spack will see it as an os
+            elif self._is_valid_os(entry, platform):
+                platform_os = platform.operating_system(entry)
             else:
-                platform_os = entry
+                raise UnknownArchitectureSpecError(entry)
 
         if target is None:
             target = platform.target('default')
         if platform_os is None:
-            platform_os = platform.operating_system('default')
+            platform_os = platform.operating_system('default_os')
 
         self.architecture = Arch(platform=platform, 
                                  platform_os=platform_os, 
@@ -1854,7 +1870,6 @@ def __init__(self):
 
     def do_parse(self):
         specs = []
-
         try:
             while self.next:
                 if self.accept(ID):
@@ -1889,7 +1904,7 @@ def spec(self):
         spec.name = self.token.value
         spec.versions = VersionList()
         spec.variants = VariantMap(spec)
-        spec.target = None
+        spec.architecture = None
         spec.compiler = None
         spec.external = None
         spec.external_module = None
@@ -1920,7 +1935,7 @@ def spec(self):
                 spec._set_compiler(self.compiler())
 
             elif self.accept(EQ):
-                spec._set_target(self.target())
+                spec._set_architecture(self.architecture())
 
             else:
                 break
@@ -1938,7 +1953,7 @@ def variant(self):
         return self.token.value
 
 
-    def target(self):
+    def architecture(self):
         self.expect(ID)
         return self.token.value
 
@@ -2077,6 +2092,13 @@ def __init__(self, pkg, variant):
         super(UnknownVariantError, self).__init__(
             "Package %s has no variant %s!" % (pkg, variant))
 
+class UnknownArchitectureSpecError(SpecError):
+    """ Raised when an entry in a string field is neither a platform,
+        operating system or a target. """
+    def __init__(self, architecture_spec_entry):
+        super(UnknownArchitectureSpecError, self).__init__(
+                "Architecture spec %s is not a valid spec entry" % (
+                                            architecture_spec_entry))
 
 class DuplicateArchitectureError(SpecError):
     """Raised when the same target occurs in a spec twice."""