Split `satisfies(..., strict=True/False)` into two functions (#35681)

This commit formalizes `satisfies(lhs, rhs, strict=True/False)`
and splits it into two functions: `satisfies(lhs, rhs)` and
`intersects(lhs, rhs)`.

- `satisfies(lhs, rhs)` means: all concrete specs matching the
   left hand side also match the right hand side
- `intersects(lhs, rhs)` means: there exist concrete specs
   matching both lhs and rhs.

`intersects` now has the property that it's commutative,
which previously was not guaranteed.

For abstract specs, `intersects(lhs, rhs)` implies that
`constrain(lhs, rhs)` works.

What's *not* done in this PR is ensuring that
`intersects(concrete, abstract)` returns false when the
abstract spec has additional properties not present in the
concrete spec, but `constrain(concrete, abstract)` will
raise an error.

To accomplish this, some semantics have changed, as well
as bugfixes to ArchSpec:
- GitVersion is now interpreted as a more constrained
  version
- Compiler flags are interpreted as strings since their
  order is important
- Abstract specs respect variant type (bool / multivalued)

1 files changed, 18 insertions, 0 deletions

diff --git a/var/spack/repos/builtin.mock/packages/v1-consumer/package.py b/var/spack/repos/builtin.mock/packages/v1-consumer/package.py
new file mode 100644
index 0000000000..230ede4871
--- /dev/null
+++ b/var/spack/repos/builtin.mock/packages/v1-consumer/package.py
@@ -0,0 +1,18 @@
+# Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+from spack.package import *
+
+
+class V1Consumer(Package):
+    """Mimic the real netlib-lapack, that may be built on top of an
+    optimized blas.
+    """
+
+    homepage = "https://dev.null"
+
+    version("1.0")
+
+    depends_on("v2")
+    depends_on("v1")