microarchitectures: fix custom compiler versions (#13222)

Custom string versions for compilers were raising a ValueError on
conversion to int. This commit fixes the behavior by trying to detect
the underlying compiler version when in presence of a custom string
version.

* Refactor code that deals with custom versions for better readability
* Partition version components with a regex
* Fix semantic of custom compiler versions with a suffix
* clang@x.y-apple has been special-cased
* Add unit tests

lib/spack/llnl/util/cpu/__init__.py

@@ -5,6 +5,7 @@
 
 from .microarchitecture import Microarchitecture, UnsupportedMicroarchitecture
 from .microarchitecture import targets, generic_microarchitecture
+from .microarchitecture import version_components
 from .detect import host
 
 __all__ = [
@@ -12,5 +13,6 @@
     'UnsupportedMicroarchitecture',
     'targets',
     'generic_microarchitecture',
-    'host'
+    'host',
+    'version_components'
 ]

lib/spack/llnl/util/cpu/microarchitecture.py

@@ -4,6 +4,7 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import functools
 import platform
+import re
 import warnings
 
 try:
@@ -219,9 +220,9 @@ def satisfies_constraint(entry, version):
             min_version, max_version = entry['versions'].split(':')
 
             # Check version suffixes
-            min_version, _, min_suffix = min_version.partition('-')
-            max_version, _, max_suffix = max_version.partition('-')
-            version, _, suffix = version.partition('-')
+            min_version, min_suffix = version_components(min_version)
+            max_version, max_suffix = version_components(max_version)
+            version, suffix = version_components(version)
 
             # If the suffixes are not all equal there's no match
             if ((suffix != min_suffix and min_version) or
@@ -277,6 +278,26 @@ def generic_microarchitecture(name):
     )
 
 
+def version_components(version):
+    """Decomposes the version passed as input in version number and
+    suffix and returns them.
+
+    If the version number of the suffix are not present, an empty
+    string is returned.
+
+    Args:
+        version (str): version to be decomposed into its components
+    """
+    match = re.match(r'([\d.]*)(-?)(.*)', str(version))
+    if not match:
+        return '', ''
+
+    version_number = match.group(1)
+    suffix = match.group(3)
+
+    return version_number, suffix
+
+
 def _known_microarchitectures():
     """Returns a dictionary of the known micro-architectures. If the
     current host platform is unknown adds it too as a generic target.