diff --git a/lib/spack/spack/package_base.py b/lib/spack/spack/package_base.py
index 305af5cb8c1..7ffb06ab4c5 100644
--- a/lib/spack/spack/package_base.py
+++ b/lib/spack/spack/package_base.py
@@ -58,6 +58,7 @@
 from spack.solver.version_order import concretization_version_order
 from spack.stage import DevelopStage, ResourceStage, Stage, StageComposite, compute_stage_name
 from spack.util.package_hash import package_hash
+from spack.util.typing import SupportsRichComparison
 from spack.version import GitVersion, StandardVersion
 
 FLAG_HANDLER_RETURN_TYPE = Tuple[
@@ -85,32 +86,6 @@
 spack_times_log = "install_times.json"
 
 
-def deprecated_version(pkg: "PackageBase", version: Union[str, StandardVersion]) -> bool:
-    """Return True iff the version is deprecated.
-
-    Arguments:
-        pkg: The package whose version is to be checked.
-        version: The version being checked
-    """
-    if not isinstance(version, StandardVersion):
-        version = StandardVersion.from_string(version)
-
-    details = pkg.versions.get(version)
-    return details is not None and details.get("deprecated", False)
-
-
-def preferred_version(pkg: "PackageBase"):
-    """
-    Returns a sorted list of the preferred versions of the package.
-
-    Arguments:
-        pkg: The package whose versions are to be assessed.
-    """
-
-    version, _ = max(pkg.versions.items(), key=concretization_version_order)
-    return version
-
-
 class WindowsRPath:
     """Collection of functionality surrounding Windows RPATH specific features
 
@@ -415,59 +390,77 @@ def remove_files_from_view(self, view, merge_map):
 
 Pb = TypeVar("Pb", bound="PackageBase")
 
-WhenDict = Dict[spack.spec.Spec, Dict[str, Any]]
-NameValuesDict = Dict[str, List[Any]]
-NameWhenDict = Dict[str, Dict[spack.spec.Spec, List[Any]]]
+# Some typedefs for dealing with when-indexed dictionaries
+#
+# Many of the dictionaries on PackageBase are of the form:
+# { Spec: { K: V } }
+#
+# K might be a variant name, a version, etc. V is a definition of some Spack object.
+# The methods below transform these types of dictionaries.
+K = TypeVar("K", bound=SupportsRichComparison)
+V = TypeVar("V")
 
 
-def _by_name(
-    when_indexed_dictionary: WhenDict, when: bool = False
-) -> Union[NameValuesDict, NameWhenDict]:
-    """Convert a dict of dicts keyed by when/name into a dict of lists keyed by name.
+def _by_subkey(
+    when_indexed_dictionary: Dict[spack.spec.Spec, Dict[K, V]], when: bool = False
+) -> Dict[K, Union[List[V], Dict[spack.spec.Spec, List[V]]]]:
+    """Convert a dict of dicts keyed by when/subkey into a dict of lists keyed by subkey.
 
     Optional Arguments:
         when: if ``True``, don't discared the ``when`` specs; return a 2-level dictionary
-            keyed by name and when spec.
+            keyed by subkey and when spec.
     """
     # very hard to define this type to be conditional on `when`
-    all_by_name: Dict[str, Any] = {}
+    all_by_subkey: Dict[K, Any] = {}
 
-    for when_spec, by_name in when_indexed_dictionary.items():
-        for name, value in by_name.items():
+    for when_spec, by_key in when_indexed_dictionary.items():
+        for key, value in by_key.items():
             if when:
-                when_dict = all_by_name.setdefault(name, {})
+                when_dict = all_by_subkey.setdefault(key, {})
                 when_dict.setdefault(when_spec, []).append(value)
             else:
-                all_by_name.setdefault(name, []).append(value)
+                all_by_subkey.setdefault(key, []).append(value)
 
     # this needs to preserve the insertion order of whens
-    return dict(sorted(all_by_name.items()))
+    return dict(sorted(all_by_subkey.items()))
 
 
-def _names(when_indexed_dictionary: WhenDict) -> List[str]:
+def _subkeys(when_indexed_dictionary: Dict[spack.spec.Spec, Dict[K, V]]) -> List[K]:
     """Get sorted names from dicts keyed by when/name."""
-    all_names = set()
-    for when, by_name in when_indexed_dictionary.items():
-        for name in by_name:
-            all_names.add(name)
+    all_keys = set()
+    for when, by_key in when_indexed_dictionary.items():
+        for key in by_key:
+            all_keys.add(key)
 
-    return sorted(all_names)
+    return sorted(all_keys)
 
 
-WhenVariantList = List[Tuple[spack.spec.Spec, spack.variant.Variant]]
+def _has_subkey(when_indexed_dictionary: Dict[spack.spec.Spec, Dict[K, V]], key: K) -> bool:
+    return any(key in dictionary for dictionary in when_indexed_dictionary.values())
 
 
-def _remove_overridden_vdefs(variant_defs: WhenVariantList) -> None:
-    """Remove variant defs from the list if their when specs are satisfied by later ones.
+def _num_definitions(when_indexed_dictionary: Dict[spack.spec.Spec, Dict[K, V]]) -> int:
+    return sum(len(dictionary) for dictionary in when_indexed_dictionary.values())
 
-    Any such variant definitions are *always* overridden by their successor, as it will
-    match everything the predecessor matches, and the solver will prefer it because of
-    its higher precedence.
 
-    We can just remove these defs from variant definitions and avoid putting them in the
-    solver. This is also useful for, e.g., `spack info`, where we don't want to show a
-    variant from a superclass if it is always overridden by a variant defined in a
-    subclass.
+def _precedence(obj) -> int:
+    """Get either a 'precedence' attribute or item from an object."""
+    precedence = getattr(obj, "precedence", None)
+    if precedence is None:
+        raise KeyError(f"Couldn't get precedence from {type(obj)}")
+    return precedence
+
+
+def _remove_overridden_defs(defs: List[Tuple[spack.spec.Spec, Any]]) -> None:
+    """Remove definitions from the list if their when specs are satisfied by later ones.
+
+    Any such definitions are *always* overridden by their successor, as they will
+    match everything the predecessor matches, and the solver will prefer them because of
+    their higher precedence.
+
+    We can just remove these defs and avoid putting them in the solver. This is also
+    useful for, e.g., `spack info`, where we don't want to show a variant from a
+    superclass if it is always overridden by a variant defined in a subclass.
 
     Example::
 
@@ -485,14 +478,33 @@ class Hipblas:
 
     """
     i = 0
-    while i < len(variant_defs):
-        when, vdef = variant_defs[i]
-        if any(when.satisfies(successor) for successor, _ in variant_defs[i + 1 :]):
-            del variant_defs[i]
+    while i < len(defs):
+        when, _ = defs[i]
+        if any(when.satisfies(successor) for successor, _ in defs[i + 1 :]):
+            del defs[i]
         else:
             i += 1
 
 
+def _definitions(
+    when_indexed_dictionary: Dict[spack.spec.Spec, Dict[K, V]], key: K
+) -> List[Tuple[spack.spec.Spec, V]]:
+    """Iterator over (when_spec, Value) for all values with a particular Key."""
+    # construct a list of defs sorted by precedence
+    defs: List[Tuple[spack.spec.Spec, V]] = []
+    for when, values_by_key in when_indexed_dictionary.items():
+        value_def = values_by_key.get(key)
+        if value_def:
+            defs.append((when, value_def))
+
+    # With multiple definitions, ensure precedence order and simplify overrides
+    if len(defs) > 1:
+        defs.sort(key=lambda v: _precedence(v[1]))
+        _remove_overridden_defs(defs)
+
+    return defs
+
+
 #: Store whether a given Spec source/binary should not be redistributed.
 class DisableRedistribute:
     def __init__(self, source, binary):
@@ -756,44 +768,32 @@ def __init__(self, spec):
 
     @classmethod
     def dependency_names(cls):
-        return _names(cls.dependencies)
+        return _subkeys(cls.dependencies)
 
     @classmethod
     def dependencies_by_name(cls, when: bool = False):
-        return _by_name(cls.dependencies, when=when)
+        return _by_subkey(cls.dependencies, when=when)
 
     # Accessors for variants
-    # External code workingw with Variants should go through the methods below
+    # External code working with Variants should go through the methods below
 
     @classmethod
     def variant_names(cls) -> List[str]:
-        return _names(cls.variants)
+        return _subkeys(cls.variants)
 
     @classmethod
     def has_variant(cls, name) -> bool:
-        return any(name in dictionary for dictionary in cls.variants.values())
+        return _has_subkey(cls.variants, name)
 
     @classmethod
     def num_variant_definitions(cls) -> int:
         """Total number of variant definitions in this class so far."""
-        return sum(len(variants_by_name) for variants_by_name in cls.variants.values())
+        return _num_definitions(cls.variants)
 
     @classmethod
-    def variant_definitions(cls, name: str) -> WhenVariantList:
+    def variant_definitions(cls, name: str) -> List[Tuple[spack.spec.Spec, spack.variant.Variant]]:
         """Iterator over (when_spec, Variant) for all variant definitions for a particular name."""
-        # construct a list of defs sorted by precedence
-        defs: WhenVariantList = []
-        for when, variants_by_name in cls.variants.items():
-            variant_def = variants_by_name.get(name)
-            if variant_def:
-                defs.append((when, variant_def))
-
-        # With multiple definitions, ensure precedence order and simplify overrides
-        if len(defs) > 1:
-            defs.sort(key=lambda v: v[1].precedence)
-            _remove_overridden_vdefs(defs)
-
-        return defs
+        return _definitions(cls.variants, name)
 
     @classmethod
     def variant_items(cls) -> Iterable[Tuple[spack.spec.Spec, Dict[str, spack.variant.Variant]]]:
@@ -2369,6 +2369,32 @@ def possible_dependencies(
     return visited
 
 
+def deprecated_version(pkg: PackageBase, version: Union[str, StandardVersion]) -> bool:
+    """Return True iff the version is deprecated.
+
+    Arguments:
+        pkg: The package whose version is to be checked.
+        version: The version being checked
+    """
+    if not isinstance(version, StandardVersion):
+        version = StandardVersion.from_string(version)
+
+    details = pkg.versions.get(version)
+    return details is not None and details.get("deprecated", False)
+
+
+def preferred_version(pkg: PackageBase):
+    """
+    Returns a sorted list of the preferred versions of the package.
+
+    Arguments:
+        pkg: The package whose versions are to be assessed.
+    """
+
+    version, _ = max(pkg.versions.items(), key=concretization_version_order)
+    return version
+
+
 class PackageStillNeededError(InstallError):
     """Raised when package is still needed by another on uninstall."""
 
diff --git a/lib/spack/spack/util/typing.py b/lib/spack/spack/util/typing.py
new file mode 100644
index 00000000000..7e1525aa4e9
--- /dev/null
+++ b/lib/spack/spack/util/typing.py
@@ -0,0 +1,30 @@
+# Copyright 2013-2024 Lawrence Livermore National Security, LLC and other: object
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from typing import Any
+
+from typing_extensions import Protocol
+
+
+class SupportsRichComparison(Protocol):
+    """Objects that support =, !=, <, <=, >, and >=."""
+
+    def __eq__(self, other: Any) -> bool:
+        raise NotImplementedError
+
+    def __ne__(self, other: Any) -> bool:
+        raise NotImplementedError
+
+    def __lt__(self, other: Any) -> bool:
+        raise NotImplementedError
+
+    def __le__(self, other: Any) -> bool:
+        raise NotImplementedError
+
+    def __gt__(self, other: Any) -> bool:
+        raise NotImplementedError
+
+    def __ge__(self, other: Any) -> bool:
+        raise NotImplementedError
diff --git a/lib/spack/spack/version/version_types.py b/lib/spack/spack/version/version_types.py
index 4c7a9606f46..b2e27445f9a 100644
--- a/lib/spack/spack/version/version_types.py
+++ b/lib/spack/spack/version/version_types.py
@@ -8,6 +8,7 @@
 from typing import Dict, Iterable, Iterator, List, Optional, Tuple, Union
 
 from spack.util.spack_yaml import syaml_dict
+from spack.util.typing import SupportsRichComparison
 
 from .common import (
     ALPHA,
@@ -156,7 +157,7 @@ def parse_string_components(string: str) -> Tuple[VersionTuple, SeparatorTuple]:
     return (release, prerelease), separators
 
 
-class VersionType:
+class VersionType(SupportsRichComparison):
     """Base type for all versions in Spack (ranges, lists, regular versions, and git versions).
 
     Versions in Spack behave like sets, and support some basic set operations. There are
@@ -193,23 +194,6 @@ def union(self, other: "VersionType") -> "VersionType":
         """Return a VersionType containing self and other."""
         raise NotImplementedError
 
-    # We can use SupportsRichComparisonT in Python 3.8 or later, but alas in 3.6 we need
-    # to write all the operators out
-    def __eq__(self, other: object) -> bool:
-        raise NotImplementedError
-
-    def __lt__(self, other: object) -> bool:
-        raise NotImplementedError
-
-    def __gt__(self, other: object) -> bool:
-        raise NotImplementedError
-
-    def __ge__(self, other: object) -> bool:
-        raise NotImplementedError
-
-    def __le__(self, other: object) -> bool:
-        raise NotImplementedError
-
     def __hash__(self) -> int:
         raise NotImplementedError