Support for prereleases (#43140)

This adds support for prereleases. Alpha, beta and release candidate
suffixes are ordered in the intuitive way:

```
1.2.0-alpha < 1.2.0-alpha.1 < 1.2.0-beta.2 < 1.2.0-rc.3 < 1.2.0 < 1.2.0-xyz
```

Alpha, beta and rc prereleases are defined as follows: split the version
string into components like before (on delimiters and string boundaries).
If there's a string component `alpha`, `beta` or `rc` followed by an optional
numeric component at the end, then the version is prerelease.

So `1.2.0-alpha.1 == 1.2.0alpha1 == 1.2.0.alpha1` are all the same, as usual.

The strings `alpha`, `beta` and `rc` are chosen because they match semver,
they are sufficiently long to be unambiguous, and and all contain at least
one non-hex character so distinguish them from shasum/digest type suffixes.

The comparison key is now stored as `(release_tuple, prerelease_tuple)`, so in
the above example:

```
((1,2,0),(ALPHA,)) < ((1,2,0),(ALPHA,1)) < ((1,2,0),(BETA,2)) < ((1,2,0),(RC,3)) < ((1,2,0),(FINAL,)) < ((1,2,0,"xyz"), (FINAL,))
```

The version ranges `@1.2.0:` and `@:1.1` do *not* include prereleases of
`1.2.0`.

So for packaging, if the `1.2.0alpha` and `1.2.0` versions have the same constraints on
dependencies, it's best to write

```python
depends_on("x@1:", when="@1.2.0alpha:")
```

However, `@1.2:` does include `1.2.0alpha`. This is because Spack considers
`1.2 < 1.2.0` as distinct versions, with `1.2 < 1.2.0alpha < 1.2.0` as a consequence.

Alternatively, the above `depends_on` statement can thus be written

```python
depends_on("x@1:", when="@1.2:")
```

which can be useful too. A short-hand to include prereleases, but you
can still be explicit to exclude the prerelease by specifying the patch version
number.

### Concretization

Concretization uses a different version order than `<`. Prereleases are ordered
between final releases and develop versions. That way, users should not
have to set `preferred=True` on every final release if they add just one
prerelease to a package. The concretizer is unlikely to pick a prerelease when
final releases are possible.

### Limitations

1. You can't express a range that includes all alpha release but excludes all beta
   releases. Only alternative is good old repeated nines: `@:1.2.0alpha99`.

2. The Python ecosystem defaults to `a`, `b`, `rc` strings, so translation of Python versions to
   Spack versions requires expansion to `alpha`, `beta`, `rc`. It's mildly annoying, because
   this means we may need to compute URLs differently (not done in this commit).

### Hash

Care is taken not to break hashes of versions that do not have a prerelease
suffix.

12 files changed, 275 insertions, 115 deletions

diff --git a/lib/spack/docs/basic_usage.rst b/lib/spack/docs/basic_usage.rst
index 5a8d9668f3..f26c6e5683 100644
--- a/lib/spack/docs/basic_usage.rst
+++ b/lib/spack/docs/basic_usage.rst
@@ -1119,6 +1119,9 @@ and ``3.4.2``.  Similarly, ``@4.2:`` means any version above and including
 ``4.2``.  As a short-hand, ``@3`` is equivalent to the range ``@3:3`` and
 includes any version with major version ``3``.
 
+Versions are ordered lexicograpically by its components. For more details
+on the order, see :ref:`the packaging guide <version-comparison>`.
+
 Notice that you can distinguish between the specific version ``@=3.2`` and
 the range ``@3.2``. This is useful for packages that follow a versioning
 scheme that omits the zero patch version number: ``3.2``, ``3.2.1``,
diff --git a/lib/spack/docs/packaging_guide.rst b/lib/spack/docs/packaging_guide.rst
index 0fa8e4dce3..7d8efa3987 100644
--- a/lib/spack/docs/packaging_guide.rst
+++ b/lib/spack/docs/packaging_guide.rst
@@ -893,26 +893,50 @@ as an option to the ``version()`` directive. Example situations would be a
 "snapshot"-like Version Control System (VCS) tag, a VCS branch such as
 ``v6-16-00-patches``, or a URL specifying a regularly updated snapshot tarball.
 
+
+.. _version-comparison:
+
 ^^^^^^^^^^^^^^^^^^
 Version comparison
 ^^^^^^^^^^^^^^^^^^
 
-Most Spack versions are numeric, a tuple of integers; for example,
-``0.1``, ``6.96`` or ``1.2.3.1``.  Spack knows how to compare and sort
-numeric versions.
-
-Some Spack versions involve slight extensions of numeric syntax; for
-example, ``py-sphinx-rtd-theme@=0.1.10a0``.  In this case, numbers are
-always considered to be "newer" than letters.  This is for consistency
-with `RPM <https://bugzilla.redhat.com/show_bug.cgi?id=50977>`_.
+Spack imposes a generic total ordering on the set of versions,
+independently from the package they are associated with.
 
-Spack versions may also be arbitrary non-numeric strings, for example
-``develop``, ``master``, ``local``.
-
-The order on versions is defined as follows. A version string is split
-into a list of components based on delimiters such as ``.``, ``-`` etc.
-Lists are then ordered lexicographically, where components are ordered
-as follows:
+Most Spack versions are numeric, a tuple of integers; for example,
+``0.1``, ``6.96`` or ``1.2.3.1``. In this very basic case, version
+comparison is lexicographical on the numeric components:
+``1.2 < 1.2.1 < 1.2.2 < 1.10``.
+
+Spack can also supports string components such as ``1.1.1a`` and
+``1.y.0``. String components are considered less than numeric
+components, so ``1.y.0 < 1.0``. This is for consistency with
+`RPM <https://bugzilla.redhat.com/show_bug.cgi?id=50977>`_. String
+components do not have to be separated by dots or any other delimiter.
+So, the contrived version ``1y0`` is identical to ``1.y.0``.
+
+Pre-release suffixes also contain string parts, but they are handled
+in a special way. For example ``1.2.3alpha1`` is parsed as a pre-release
+of the version ``1.2.3``. This allows Spack to order it before the
+actual release: ``1.2.3alpha1 < 1.2.3``. Spack supports alpha, beta and
+release candidate suffixes: ``1.2alpha1 < 1.2beta1 < 1.2rc1 < 1.2``. Any
+suffix not recognized as a pre-release is treated as an ordinary
+string component, so ``1.2 < 1.2-mysuffix``.
+
+Finally, there are a few special string components that are considered
+"infinity versions". They include ``develop``, ``main``, ``master``,
+``head``, ``trunk``, and ``stable``. For example: ``1.2 < develop``.
+These are useful for specifying the most recent development version of
+a package (often a moving target like a git branch), without assigning
+a specific version number. Infinity versions are not automatically used when determining the latest version of a package unless explicitly required by another package or user.
+
+More formally, the order on versions is defined as follows. A version
+string is split into a list of components based on delimiters such as
+``.`` and ``-`` and string boundaries. The components are split into
+the **release** and a possible **pre-release** (if the last component
+is numeric and the second to last is a string ``alpha``, ``beta`` or ``rc``).
+The release components are ordered lexicographically, with comparsion
+between different types of components as follows:
 
 #. The following special strings are considered larger than any other
    numeric or non-numeric version component, and satisfy the following
@@ -925,6 +949,9 @@ as follows:
 #. All other non-numeric components are less than numeric components,
    and are ordered alphabetically.
 
+Finally, if the release components are equal, the pre-release components
+are used to break the tie, in the obvious way.
+
 The logic behind this sort order is two-fold:
 
 #. Non-numeric versions are usually used for special cases while
diff --git a/lib/spack/spack/solver/asp.py b/lib/spack/spack/solver/asp.py
index c2524b1223..2cf4b5cbf4 100644
--- a/lib/spack/spack/solver/asp.py
+++ b/lib/spack/spack/solver/asp.py
@@ -541,6 +541,7 @@ def _concretization_version_order(version_info: Tuple[GitOrStandardVersion, dict
         info.get("preferred", False),
         not info.get("deprecated", False),
         not version.isdevelop(),
+        not version.is_prerelease(),
         version,
     )
 
@@ -2158,7 +2159,7 @@ class SpackSolverSetup:
             if isinstance(v, vn.StandardVersion):
                 return [v]
             elif isinstance(v, vn.ClosedOpenRange):
-                return [v.lo, vn.prev_version(v.hi)]
+                return [v.lo, vn._prev_version(v.hi)]
             elif isinstance(v, vn.VersionList):
                 return sum((versions_for(e) for e in v), [])
             else:
diff --git a/lib/spack/spack/target.py b/lib/spack/spack/target.py
index 5f1f4f9e5a..8f9e6dcf51 100644
--- a/lib/spack/spack/target.py
+++ b/lib/spack/spack/target.py
@@ -155,5 +155,6 @@ class Target:
                 # log this and just return compiler.version instead
                 tty.debug(str(e))
 
-        compiler_version = compiler_version.dotted.force_numeric
-        return self.microarchitecture.optimization_flags(compiler.name, str(compiler_version))
+        return self.microarchitecture.optimization_flags(
+            compiler.name, compiler_version.dotted_numeric_string
+        )
diff --git a/lib/spack/spack/test/concretize.py b/lib/spack/spack/test/concretize.py
index b12fbfb910..a68d0f7d34 100644
--- a/lib/spack/spack/test/concretize.py
+++ b/lib/spack/spack/test/concretize.py
@@ -2613,3 +2613,28 @@ def test_reusable_externals_different_spec(mock_packages, tmpdir):
         {"mpich": {"externals": [{"spec": "mpich@4.1 +debug", "prefix": tmpdir.strpath}]}},
         local=False,
     )
+
+
+def test_concretization_version_order():
+    versions = [
+        (Version("develop"), {}),
+        (Version("1.0"), {}),
+        (Version("2.0"), {"deprecated": True}),
+        (Version("1.1"), {}),
+        (Version("1.1alpha1"), {}),
+        (Version("0.9"), {"preferred": True}),
+    ]
+    result = [
+        v
+        for v, _ in sorted(
+            versions, key=spack.solver.asp._concretization_version_order, reverse=True
+        )
+    ]
+    assert result == [
+        Version("0.9"),  # preferred
+        Version("1.1"),  # latest non-deprecated final version
+        Version("1.0"),  # latest non-deprecated final version
+        Version("1.1alpha1"),  # prereleases
+        Version("develop"),  # likely development version
+        Version("2.0"),  # deprecated
+    ]
diff --git a/lib/spack/spack/test/url_fetch.py b/lib/spack/spack/test/url_fetch.py
index 406344ebfb..6dd548d858 100644
--- a/lib/spack/spack/test/url_fetch.py
+++ b/lib/spack/spack/test/url_fetch.py
@@ -210,16 +210,10 @@ def test_from_list_url(mock_packages, config, spec, url, digest, _fetch_method):
 @pytest.mark.parametrize(
     "requested_version,tarball,digest",
     [
-        # This version is in the web data path (test/data/web/4.html), but not in the
+        # These versions are in the web data path (test/data/web/4.html), but not in the
         # url-list-test package. We expect Spack to generate a URL with the new version.
         ("=4.5.0", "foo-4.5.0.tar.gz", None),
-        # This version is in web data path and not in the package file, BUT the 2.0.0b2
-        # version in the package file satisfies 2.0.0, so Spack will use the known version.
-        # TODO: this is *probably* not what the user wants, but it's here as an example
-        # TODO: for that reason. We can't express "exactly 2.0.0" right now, and we don't
-        # TODO: have special cases that would make 2.0.0b2 less than 2.0.0. We should
-        # TODO: probably revisit this in our versioning scheme.
-        ("2.0.0", "foo-2.0.0b2.tar.gz", "000000000000000000000000000200b2"),
+        ("=2.0.0", "foo-2.0.0.tar.gz", None),
     ],
 )
 @pytest.mark.only_clingo("Original concretizer doesn't resolve concrete versions to known ones")
@@ -228,7 +222,7 @@ def test_new_version_from_list_url(
 ):
     """Test non-specific URLs from the url-list-test package."""
     with spack.config.override("config:url_fetch_method", _fetch_method):
-        s = Spec("url-list-test @%s" % requested_version).concretized()
+        s = Spec(f"url-list-test @{requested_version}").concretized()
         fetch_strategy = fs.from_list_url(s.package)
 
         assert isinstance(fetch_strategy, fs.URLFetchStrategy)
diff --git a/lib/spack/spack/test/versions.py b/lib/spack/spack/test/versions.py
index 48ab551060..bc97fe4667 100644
--- a/lib/spack/spack/test/versions.py
+++ b/lib/spack/spack/test/versions.py
@@ -213,12 +213,24 @@ def test_nums_and_patch():
     assert_ver_gt("=6.5p1", "=5.6p1")
 
 
-def test_rc_versions():
-    assert_ver_gt("=6.0.rc1", "=6.0")
-    assert_ver_lt("=6.0", "=6.0.rc1")
+def test_prereleases():
+    # pre-releases are special: they are less than final releases
+    assert_ver_lt("=6.0alpha", "=6.0alpha0")
+    assert_ver_lt("=6.0alpha0", "=6.0alpha1")
+    assert_ver_lt("=6.0alpha1", "=6.0alpha2")
+    assert_ver_lt("=6.0alpha2", "=6.0beta")
+    assert_ver_lt("=6.0beta", "=6.0beta0")
+    assert_ver_lt("=6.0beta0", "=6.0beta1")
+    assert_ver_lt("=6.0beta1", "=6.0beta2")
+    assert_ver_lt("=6.0beta2", "=6.0rc")
+    assert_ver_lt("=6.0rc", "=6.0rc0")
+    assert_ver_lt("=6.0rc0", "=6.0rc1")
+    assert_ver_lt("=6.0rc1", "=6.0rc2")
+    assert_ver_lt("=6.0rc2", "=6.0")
 
 
 def test_alpha_beta():
+    # these are not pre-releases, but ordinary string components.
     assert_ver_gt("=10b2", "=10a1")
     assert_ver_lt("=10a2", "=10b2")
 
@@ -277,6 +289,39 @@ def test_version_ranges():
     assert_ver_gt("1.5:1.6", "1.2:1.4")
 
 
+def test_version_range_with_prereleases():
+    # 1.2.1: means from the 1.2.1 release onwards
+    assert_does_not_satisfy("1.2.1alpha1", "1.2.1:")
+    assert_does_not_satisfy("1.2.1beta2", "1.2.1:")
+    assert_does_not_satisfy("1.2.1rc3", "1.2.1:")
+
+    # Pre-releases of 1.2.1 are included in the 1.2.0: range
+    assert_satisfies("1.2.1alpha1", "1.2.0:")
+    assert_satisfies("1.2.1beta1", "1.2.0:")
+    assert_satisfies("1.2.1rc3", "1.2.0:")
+
+    # In Spack 1.2 and 1.2.0 are distinct with 1.2 < 1.2.0. So a lowerbound on 1.2 includes
+    # pre-releases of 1.2.0 as well.
+    assert_satisfies("1.2.0alpha1", "1.2:")
+    assert_satisfies("1.2.0beta2", "1.2:")
+    assert_satisfies("1.2.0rc3", "1.2:")
+
+    # An upperbound :1.1 does not include 1.2.0 pre-releases
+    assert_does_not_satisfy("1.2.0alpha1", ":1.1")
+    assert_does_not_satisfy("1.2.0beta2", ":1.1")
+    assert_does_not_satisfy("1.2.0rc3", ":1.1")
+
+    assert_satisfies("1.2.0alpha1", ":1.2")
+    assert_satisfies("1.2.0beta2", ":1.2")
+    assert_satisfies("1.2.0rc3", ":1.2")
+
+    # You can also construct ranges from prereleases
+    assert_satisfies("1.2.0alpha2:1.2.0beta1", "1.2.0alpha1:1.2.0beta2")
+    assert_satisfies("1.2.0", "1.2.0alpha1:")
+    assert_satisfies("=1.2.0", "1.2.0alpha1:")
+    assert_does_not_satisfy("=1.2.0", ":1.2.0rc345")
+
+
 def test_contains():
     assert_in("=1.3", "1.2:1.4")
     assert_in("=1.2.5", "1.2:1.4")
@@ -417,12 +462,12 @@ def test_basic_version_satisfaction():
     assert_satisfies("4.7.3", "4.7.3")
 
     assert_satisfies("4.7.3", "4.7")
-    assert_satisfies("4.7.3b2", "4.7")
-    assert_satisfies("4.7b6", "4.7")
+    assert_satisfies("4.7.3v2", "4.7")
+    assert_satisfies("4.7v6", "4.7")
 
     assert_satisfies("4.7.3", "4")
-    assert_satisfies("4.7.3b2", "4")
-    assert_satisfies("4.7b6", "4")
+    assert_satisfies("4.7.3v2", "4")
+    assert_satisfies("4.7v6", "4")
 
     assert_does_not_satisfy("4.8.0", "4.9")
     assert_does_not_satisfy("4.8", "4.9")
@@ -433,12 +478,12 @@ def test_basic_version_satisfaction_in_lists():
     assert_satisfies(["4.7.3"], ["4.7.3"])
 
     assert_satisfies(["4.7.3"], ["4.7"])
-    assert_satisfies(["4.7.3b2"], ["4.7"])
-    assert_satisfies(["4.7b6"], ["4.7"])
+    assert_satisfies(["4.7.3v2"], ["4.7"])
+    assert_satisfies(["4.7v6"], ["4.7"])
 
     assert_satisfies(["4.7.3"], ["4"])
-    assert_satisfies(["4.7.3b2"], ["4"])
-    assert_satisfies(["4.7b6"], ["4"])
+    assert_satisfies(["4.7.3v2"], ["4"])
+    assert_satisfies(["4.7v6"], ["4"])
 
     assert_does_not_satisfy(["4.8.0"], ["4.9"])
     assert_does_not_satisfy(["4.8"], ["4.9"])
@@ -507,6 +552,11 @@ def test_formatted_strings():
         assert v.dotted.joined.string == "123b"
 
 
+def test_dotted_numeric_string():
+    assert Version("1a2b3").dotted_numeric_string == "1.0.2.0.3"
+    assert Version("1a2b3alpha4").dotted_numeric_string == "1.0.2.0.3.0.4"
+
+
 def test_up_to():
     v = Version("1.23-4_5b")
 
@@ -548,9 +598,18 @@ def test_repr_and_str():
     check_repr_and_str("R2016a.2-3_4")
 
 
+@pytest.mark.parametrize(
+    "version_str", ["1.2string3", "1.2-3xyz_4-alpha.5", "1.2beta", "1_x_rc-4"]
+)
+def test_stringify_version(version_str):
+    v = Version(version_str)
+    v.string = None
+    assert str(v) == version_str
+
+
 def test_len():
     a = Version("1.2.3.4")
-    assert len(a) == len(a.version)
+    assert len(a) == len(a.version[0])
     assert len(a) == 4
     b = Version("2018.0")
     assert len(b) == 2
diff --git a/lib/spack/spack/version/__init__.py b/lib/spack/spack/version/__init__.py
index 30dd71ea62..18d739ae0c 100644
--- a/lib/spack/spack/version/__init__.py
+++ b/lib/spack/spack/version/__init__.py
@@ -30,9 +30,9 @@ from .version_types import (
     Version,
     VersionList,
     VersionRange,
+    _next_version,
+    _prev_version,
     from_string,
-    next_version,
-    prev_version,
     ver,
 )
 
@@ -46,8 +46,8 @@ __all__ = [
     "from_string",
     "is_git_version",
     "infinity_versions",
-    "prev_version",
-    "next_version",
+    "_prev_version",
+    "_next_version",
     "VersionList",
     "ClosedOpenRange",
     "StandardVersion",
diff --git a/lib/spack/spack/version/common.py b/lib/spack/spack/version/common.py
index 3afa218d4d..89434d3930 100644
--- a/lib/spack/spack/version/common.py
+++ b/lib/spack/spack/version/common.py
@@ -15,6 +15,14 @@ infinity_versions = ["stable", "trunk", "head", "master", "main", "develop"]
 
 iv_min_len = min(len(s) for s in infinity_versions)
 
+ALPHA = 0
+BETA = 1
+RC = 2
+FINAL = 3
+
+PRERELEASE_TO_STRING = ["alpha", "beta", "rc"]
+STRING_TO_PRERELEASE = {"alpha": ALPHA, "beta": BETA, "rc": RC, "final": FINAL}
+
 
 def is_git_version(string: str) -> bool:
     return (
diff --git a/lib/spack/spack/version/version_types.py b/lib/spack/spack/version/version_types.py
index 3e403256ea..b772cd9d90 100644
--- a/lib/spack/spack/version/version_types.py
+++ b/lib/spack/spack/version/version_types.py
@@ -11,7 +11,11 @@ from typing import List, Optional, Tuple, Union
 from spack.util.spack_yaml import syaml_dict
 
 from .common import (
+    ALPHA,
     COMMIT_VERSION,
+    FINAL,
+    PRERELEASE_TO_STRING,
+    STRING_TO_PRERELEASE,
     EmptyRangeError,
     VersionLookupError,
     infinity_versions,
@@ -88,21 +92,50 @@ def parse_string_components(string: str) -> Tuple[tuple, tuple]:
         raise ValueError("Bad characters in version string: %s" % string)
 
     segments = SEGMENT_REGEX.findall(string)
-    version = tuple(int(m[0]) if m[0] else VersionStrComponent.from_string(m[1]) for m in segments)
     separators = tuple(m[2] for m in segments)
-    return version, separators
+    prerelease: Tuple[int, ...]
+
+    # <version>(alpha|beta|rc)<number>
+    if len(segments) >= 3 and segments[-2][1] in STRING_TO_PRERELEASE and segments[-1][0]:
+        prerelease = (STRING_TO_PRERELEASE[segments[-2][1]], int(segments[-1][0]))
+        segments = segments[:-2]
+
+    # <version>(alpha|beta|rc)
+    elif len(segments) >= 2 and segments[-1][1] in STRING_TO_PRERELEASE:
+        prerelease = (STRING_TO_PRERELEASE[segments[-1][1]],)
+        segments = segments[:-1]
+
+    # <version>
+    else:
+        prerelease = (FINAL,)
+
+    release = tuple(int(m[0]) if m[0] else VersionStrComponent.from_string(m[1]) for m in segments)
+
+    return (release, prerelease), separators
 
 
 class ConcreteVersion:
     pass
 
 
+def _stringify_version(versions: Tuple[tuple, tuple], separators: tuple) -> str:
+    release, prerelease = versions
+    string = ""
+    for i in range(len(release)):
+        string += f"{release[i]}{separators[i]}"
+    if prerelease[0] != FINAL:
+        string += f"{PRERELEASE_TO_STRING[prerelease[0]]}{separators[len(release)]}"
+        if len(prerelease) > 1:
+            string += str(prerelease[1])
+    return string
+
+
 class StandardVersion(ConcreteVersion):
     """Class to represent versions"""
 
     __slots__ = ["version", "string", "separators"]
 
-    def __init__(self, string: Optional[str], version: tuple, separators: tuple):
+    def __init__(self, string: Optional[str], version: Tuple[tuple, tuple], separators: tuple):
         self.string = string
         self.version = version
         self.separators = separators
@@ -113,11 +146,13 @@ class StandardVersion(ConcreteVersion):
 
     @staticmethod
     def typemin():
-        return StandardVersion("", (), ())
+        return StandardVersion("", ((), (ALPHA,)), ("",))
 
     @staticmethod
     def typemax():
-        return StandardVersion("infinity", (VersionStrComponent(len(infinity_versions)),), ())
+        return StandardVersion(
+            "infinity", ((VersionStrComponent(len(infinity_versions)),), (FINAL,)), ("",)
+        )
 
     def __bool__(self):
         return True
@@ -164,21 +199,23 @@ class StandardVersion(ConcreteVersion):
         return NotImplemented
 
     def __iter__(self):
-        return iter(self.version)
+        return iter(self.version[0])
 
     def __len__(self):
-        return len(self.version)
+        return len(self.version[0])
 
     def __getitem__(self, idx):
         cls = type(self)
 
+        release = self.version[0]
+
         if isinstance(idx, numbers.Integral):
-            return self.version[idx]
+            return release[idx]
 
         elif isinstance(idx, slice):
             string_arg = []
 
-            pairs = zip(self.version[idx], self.separators[idx])
+            pairs = zip(release[idx], self.separators[idx])
             for token, sep in pairs:
                 string_arg.append(str(token))
                 string_arg.append(str(sep))
@@ -193,22 +230,16 @@ class StandardVersion(ConcreteVersion):
         message = "{cls.__name__} indices must be integers"
         raise TypeError(message.format(cls=cls))
 
-    def _stringify(self):
-        string = ""
-        for index in range(len(self.version)):
-            string += str(self.version[index])
-            string += str(self.separators[index])
-        return string
-
     def __str__(self):
-        return self.string or self._stringify()
+        return self.string or _stringify_version(self.version, self.separators)
 
     def __repr__(self) -> str:
         # Print indirect repr through Version(...)
         return f'Version("{str(self)}")'
 
     def __hash__(self):
-        return hash(self.version)
+        # If this is a final release, do not hash the prerelease part for backward compat.
+        return hash(self.version if self.is_prerelease() else self.version[0])
 
     def __contains__(rhs, lhs):
         # We should probably get rid of `x in y` for versions, since
@@ -257,23 +288,22 @@ class StandardVersion(ConcreteVersion):
     def isdevelop(self):
         """Triggers on the special case of the `@develop-like` version."""
         return any(
-            isinstance(p, VersionStrComponent) and isinstance(p.data, int) for p in self.version
+            isinstance(p, VersionStrComponent) and isinstance(p.data, int) for p in self.version[0]
         )
 
+    def is_prerelease(self) -> bool:
+        return self.version[1][0] != FINAL
+
     @property
-    def force_numeric(self):
-        """Replaces all non-numeric components of the version with 0
+    def dotted_numeric_string(self) -> str:
+        """Replaces all non-numeric components of the version with 0.
 
         This can be used to pass Spack versions to libraries that have stricter version schema.
         """
-        numeric = tuple(0 if isinstance(v, VersionStrComponent) else v for v in self.version)
-        # null separators except the final one have to be converted to avoid concatenating ints
-        # default to '.' as most common delimiter for versions
-        separators = tuple(
-            "." if s == "" and i != len(self.separators) - 1 else s
-            for i, s in enumerate(self.separators)
-        )
-        return type(self)(None, numeric, separators)
+        numeric = tuple(0 if isinstance(v, VersionStrComponent) else v for v in self.version[0])
+        if self.is_prerelease():
+            numeric += (0, *self.version[1][1:])
+        return ".".join(str(v) for v in numeric)
 
     @property
     def dotted(self):
@@ -591,6 +621,9 @@ class GitVersion(ConcreteVersion):
     def isdevelop(self):
         return self.ref_version.isdevelop()
 
+    def is_prerelease(self) -> bool:
+        return self.ref_version.is_prerelease()
+
     @property
     def dotted(self) -> StandardVersion:
         return self.ref_version.dotted
@@ -622,14 +655,14 @@ class ClosedOpenRange:
     def from_version_range(cls, lo: StandardVersion, hi: StandardVersion):
         """Construct ClosedOpenRange from lo:hi range."""
         try:
-            return ClosedOpenRange(lo, next_version(hi))
+            return ClosedOpenRange(lo, _next_version(hi))
         except EmptyRangeError as e:
             raise EmptyRangeError(f"{lo}:{hi} is an empty range") from e
 
     def __str__(self):
         # This simplifies 3.1:<3.2 to 3.1:3.1 to 3.1
         # 3:3 -> 3
-        hi_prev = prev_version(self.hi)
+        hi_prev = _prev_version(self.hi)
         if self.lo != StandardVersion.typemin() and self.lo == hi_prev:
             return str(self.lo)
         lhs = "" if self.lo == StandardVersion.typemin() else str(self.lo)
@@ -641,7 +674,7 @@ class ClosedOpenRange:
 
     def __hash__(self):
         # prev_version for backward compat.
-        return hash((self.lo, prev_version(self.hi)))
+        return hash((self.lo, _prev_version(self.hi)))
 
     def __eq__(self, other):
         if isinstance(other, StandardVersion):
@@ -823,7 +856,7 @@ class VersionList:
         v = self[0]
         if isinstance(v, ConcreteVersion):
             return v
-        if isinstance(v, ClosedOpenRange) and next_version(v.lo) == v.hi:
+        if isinstance(v, ClosedOpenRange) and _next_version(v.lo) == v.hi:
             return v.lo
         return None
 
@@ -994,7 +1027,7 @@ class VersionList:
         return str(self.versions)
 
 
-def next_str(s: str) -> str:
+def _next_str(s: str) -> str:
     """Produce the next string of A-Z and a-z characters"""
     return (
         (s + "A")
@@ -1003,7 +1036,7 @@ def next_str(s: str) -> str:
     )
 
 
-def prev_str(s: str) -> str:
+def _prev_str(s: str) -> str:
     """Produce the previous string of A-Z and a-z characters"""
     return (
         s[:-1]
@@ -1012,7 +1045,7 @@ def prev_str(s: str) -> str:
     )
 
 
-def next_version_str_component(v: VersionStrComponent) -> VersionStrComponent:
+def _next_version_str_component(v: VersionStrComponent) -> VersionStrComponent:
     """
     Produce the next VersionStrComponent, where
     masteq -> mastes
@@ -1025,14 +1058,14 @@ def next_version_str_component(v: VersionStrComponent) -> VersionStrComponent:
 
     # Find the next non-infinity string.
     while True:
-        data = next_str(data)
+        data = _next_str(data)
         if data not in infinity_versions:
             break
 
     return VersionStrComponent(data)
 
 
-def prev_version_str_component(v: VersionStrComponent) -> VersionStrComponent:
+def _prev_version_str_component(v: VersionStrComponent) -> VersionStrComponent:
     """
     Produce the previous VersionStrComponent, where
     mastes -> masteq
@@ -1045,47 +1078,56 @@ def prev_version_str_component(v: VersionStrComponent) -> VersionStrComponent:
 
     # Find the next string.
     while True:
-        data = prev_str(data)
+        data = _prev_str(data)
         if data not in infinity_versions:
             break
 
     return VersionStrComponent(data)
 
 
-def next_version(v: StandardVersion) -> StandardVersion:
-    if len(v.version) == 0:
-        nxt = VersionStrComponent("A")
-    elif isinstance(v.version[-1], VersionStrComponent):
-        nxt = next_version_str_component(v.version[-1])
+def _next_version(v: StandardVersion) -> StandardVersion:
+    release, prerelease = v.version
+    separators = v.separators
+    prerelease_type = prerelease[0]
+    if prerelease_type != FINAL:
+        prerelease = (prerelease_type, prerelease[1] + 1 if len(prerelease) > 1 else 0)
+    elif len(release) == 0:
+        release = (VersionStrComponent("A"),)
+        separators = ("",)
+    elif isinstance(release[-1], VersionStrComponent):
+        release = release[:-1] + (_next_version_str_component(release[-1]),)
     else:
-        nxt = v.version[-1] + 1
-
-    # Construct a string-version for printing
-    string_components = []
-    for part, sep in zip(v.version[:-1], v.separators):
-        string_components.append(str(part))
-        string_components.append(str(sep))
-    string_components.append(str(nxt))
-
-    return StandardVersion("".join(string_components), v.version[:-1] + (nxt,), v.separators)
-
-
-def prev_version(v: StandardVersion) -> StandardVersion:
-    if len(v.version) == 0:
+        release = release[:-1] + (release[-1] + 1,)
+    components = [""] * (2 * len(release))
+    components[::2] = release
+    components[1::2] = separators[: len(release)]
+    if prerelease_type != FINAL:
+        components.extend((PRERELEASE_TO_STRING[prerelease_type], prerelease[1]))
+    return StandardVersion("".join(str(c) for c in components), (release, prerelease), separators)
+
+
+def _prev_version(v: StandardVersion) -> StandardVersion:
+    # this function does not deal with underflow, because it's always called as
+    # _prev_version(_next_version(v)).
+    release, prerelease = v.version
+    separators = v.separators
+    prerelease_type = prerelease[0]
+    if prerelease_type != FINAL:
+        prerelease = (
+            (prerelease_type,) if prerelease[1] == 0 else (prerelease_type, prerelease[1] - 1)
+        )
+    elif len(release) == 0:
         return v
-    elif isinstance(v.version[-1], VersionStrComponent):
-        prev = prev_version_str_component(v.version[-1])
+    elif isinstance(release[-1], VersionStrComponent):
+        release = release[:-1] + (_prev_version_str_component(release[-1]),)
     else:
-        prev = v.version[-1] - 1
-
-    # Construct a string-version for printing
-    string_components = []
-    for part, sep in zip(v.version[:-1], v.separators):
-        string_components.append(str(part))
-        string_components.append(str(sep))
-    string_components.append(str(prev))
-
-    return StandardVersion("".join(string_components), v.version[:-1] + (prev,), v.separators)
+        release = release[:-1] + (release[-1] - 1,)
+    components = [""] * (2 * len(release))
+    components[::2] = release
+    components[1::2] = separators[: len(release)]
+    if prerelease_type != FINAL:
+        components.extend((PRERELEASE_TO_STRING[prerelease_type], *prerelease[1:]))
+    return StandardVersion("".join(str(c) for c in components), (release, prerelease), separators)
 
 
 def Version(string: Union[str, int]) -> Union[GitVersion, StandardVersion]:
diff --git a/var/spack/repos/builtin/packages/py-azure-cli/package.py b/var/spack/repos/builtin/packages/py-azure-cli/package.py
index 43f8f546a8..27cb5a34c5 100644
--- a/var/spack/repos/builtin/packages/py-azure-cli/package.py
+++ b/var/spack/repos/builtin/packages/py-azure-cli/package.py
@@ -76,7 +76,7 @@ class PyAzureCli(PythonPackage):
     depends_on("py-azure-mgmt-recoveryservices@0.4.0:0.4", type=("build", "run"))
     depends_on("py-azure-mgmt-recoveryservicesbackup@0.6.0:0.6", type=("build", "run"))
     depends_on("py-azure-mgmt-redhatopenshift@0.1.0", type=("build", "run"))
-    depends_on("py-azure-mgmt-redis@7.0.0:7.0", type=("build", "run"))
+    depends_on("py-azure-mgmt-redis@7.0", type=("build", "run"))
     depends_on("py-azure-mgmt-relay@0.1.0:0.1", type=("build", "run"))
     depends_on("py-azure-mgmt-reservations@0.6.0", type=("build", "run"))
     depends_on("py-azure-mgmt-search@2.0:2", type=("build", "run"))
diff --git a/var/spack/repos/builtin/packages/py-gtdbtk/package.py b/var/spack/repos/builtin/packages/py-gtdbtk/package.py
index a78e86eed0..08eda2bc7d 100644
--- a/var/spack/repos/builtin/packages/py-gtdbtk/package.py
+++ b/var/spack/repos/builtin/packages/py-gtdbtk/package.py
@@ -28,7 +28,7 @@ class PyGtdbtk(PythonPackage):
     depends_on("py-pydantic@1.9.2:1", type=("build", "run"), when="@2.3.0:")
     depends_on("prodigal@2.6.2:", type=("build", "run"))
     depends_on("hmmer@3.1b2:", type=("build", "run"))
-    depends_on("pplacer@1.1:", type=("build", "run"))
+    depends_on("pplacer@1.1alpha:", type=("build", "run"))
     depends_on("fastani@1.32:", type=("build", "run"))
     depends_on("fasttree@2.1.9:", type=("build", "run"))
     depends_on("mash@2.2:", type=("build", "run"))