solver: partition classes related to requirement parsing into their own file (#47915)

3 files changed, 238 insertions, 224 deletions

diff --git a/lib/spack/spack/solver/asp.py b/lib/spack/spack/solver/asp.py
index a57e1183b4..436776e272 100644
--- a/lib/spack/spack/solver/asp.py
+++ b/lib/spack/spack/solver/asp.py
@@ -48,8 +48,6 @@ import spack.variant as vt
 import spack.version as vn
 import spack.version.git_ref_lookup
 from spack import traverse
-from spack.config import get_mark_from_yaml_data
-from spack.error import SpecSyntaxError
 
 from .core import (
     AspFunction,
@@ -65,6 +63,7 @@ from .core import (
     parse_term,
 )
 from .counter import FullDuplicatesCounter, MinimalDuplicatesCounter, NoDuplicatesCounter
+from .requirements import RequirementKind, RequirementParser, RequirementRule
 from .version_order import concretization_version_order
 
 GitOrStandardVersion = Union[spack.version.GitVersion, spack.version.StandardVersion]
@@ -144,17 +143,6 @@ def named_spec(
         spec.name = old_name
 
 
-class RequirementKind(enum.Enum):
-    """Purpose / provenance of a requirement"""
-
-    #: Default requirement expressed under the 'all' attribute of packages.yaml
-    DEFAULT = enum.auto()
-    #: Requirement expressed on a virtual package
-    VIRTUAL = enum.auto()
-    #: Requirement expressed on a specific package
-    PACKAGE = enum.auto()
-
-
 class DeclaredVersion(NamedTuple):
     """Data class to contain information on declared versions used in the solve"""
 
@@ -757,17 +745,6 @@ class ErrorHandler:
         raise UnsatisfiableSpecError(msg)
 
 
-class RequirementRule(NamedTuple):
-    """Data class to collect information on a requirement"""
-
-    pkg_name: str
-    policy: str
-    requirements: List["spack.spec.Spec"]
-    condition: "spack.spec.Spec"
-    kind: RequirementKind
-    message: Optional[str]
-
-
 class KnownCompiler(NamedTuple):
     """Data class to collect information on compilers"""
 
@@ -1146,6 +1123,7 @@ class SpackSolverSetup:
     def __init__(self, tests: bool = False):
         # these are all initialized in setup()
         self.gen: "ProblemInstanceBuilder" = ProblemInstanceBuilder()
+        self.requirement_parser = RequirementParser(spack.config.CONFIG)
         self.possible_virtuals: Set[str] = set()
 
         self.assumptions: List[Tuple["clingo.Symbol", bool]] = []  # type: ignore[name-defined]
@@ -1332,8 +1310,7 @@ class SpackSolverSetup:
             self.gen.newline()
 
     def package_requirement_rules(self, pkg):
-        parser = RequirementParser(spack.config.CONFIG)
-        self.emit_facts_from_requirement_rules(parser.rules(pkg))
+        self.emit_facts_from_requirement_rules(self.requirement_parser.rules(pkg))
 
     def pkg_rules(self, pkg, tests):
         pkg = self.pkg_class(pkg)
@@ -1811,9 +1788,8 @@ class SpackSolverSetup:
 
     def provider_requirements(self):
         self.gen.h2("Requirements on virtual providers")
-        parser = RequirementParser(spack.config.CONFIG)
         for virtual_str in sorted(self.possible_virtuals):
-            rules = parser.rules_from_virtual(virtual_str)
+            rules = self.requirement_parser.rules_from_virtual(virtual_str)
             if rules:
                 self.emit_facts_from_requirement_rules(rules)
                 self.trigger_rules()
@@ -3088,202 +3064,6 @@ class ProblemInstanceBuilder:
         return "".join(self.asp_problem)
 
 
-def parse_spec_from_yaml_string(string: str) -> "spack.spec.Spec":
-    """Parse a spec from YAML and add file/line info to errors, if it's available.
-
-    Parse a ``Spec`` from the supplied string, but also intercept any syntax errors and
-    add file/line information for debugging using file/line annotations from the string.
-
-    Arguments:
-        string: a string representing a ``Spec`` from config YAML.
-
-    """
-    try:
-        return spack.spec.Spec(string)
-    except SpecSyntaxError as e:
-        mark = get_mark_from_yaml_data(string)
-        if mark:
-            msg = f"{mark.name}:{mark.line + 1}: {str(e)}"
-            raise SpecSyntaxError(msg) from e
-        raise e
-
-
-class RequirementParser:
-    """Parses requirements from package.py files and configuration, and returns rules."""
-
-    def __init__(self, configuration):
-        self.config = configuration
-
-    def rules(self, pkg: "spack.package_base.PackageBase") -> List[RequirementRule]:
-        result = []
-        result.extend(self.rules_from_package_py(pkg))
-        result.extend(self.rules_from_require(pkg))
-        result.extend(self.rules_from_prefer(pkg))
-        result.extend(self.rules_from_conflict(pkg))
-        return result
-
-    def rules_from_package_py(self, pkg) -> List[RequirementRule]:
-        rules = []
-        for when_spec, requirement_list in pkg.requirements.items():
-            for requirements, policy, message in requirement_list:
-                rules.append(
-                    RequirementRule(
-                        pkg_name=pkg.name,
-                        policy=policy,
-                        requirements=requirements,
-                        kind=RequirementKind.PACKAGE,
-                        condition=when_spec,
-                        message=message,
-                    )
-                )
-        return rules
-
-    def rules_from_virtual(self, virtual_str: str) -> List[RequirementRule]:
-        requirements = self.config.get("packages", {}).get(virtual_str, {}).get("require", [])
-        return self._rules_from_requirements(
-            virtual_str, requirements, kind=RequirementKind.VIRTUAL
-        )
-
-    def rules_from_require(self, pkg: "spack.package_base.PackageBase") -> List[RequirementRule]:
-        kind, requirements = self._raw_yaml_data(pkg, section="require")
-        return self._rules_from_requirements(pkg.name, requirements, kind=kind)
-
-    def rules_from_prefer(self, pkg: "spack.package_base.PackageBase") -> List[RequirementRule]:
-        result = []
-        kind, preferences = self._raw_yaml_data(pkg, section="prefer")
-        for item in preferences:
-            spec, condition, message = self._parse_prefer_conflict_item(item)
-            result.append(
-                # A strong preference is defined as:
-                #
-                # require:
-                # - any_of: [spec_str, "@:"]
-                RequirementRule(
-                    pkg_name=pkg.name,
-                    policy="any_of",
-                    requirements=[spec, spack.spec.Spec("@:")],
-                    kind=kind,
-                    message=message,
-                    condition=condition,
-                )
-            )
-        return result
-
-    def rules_from_conflict(self, pkg: "spack.package_base.PackageBase") -> List[RequirementRule]:
-        result = []
-        kind, conflicts = self._raw_yaml_data(pkg, section="conflict")
-        for item in conflicts:
-            spec, condition, message = self._parse_prefer_conflict_item(item)
-            result.append(
-                # A conflict is defined as:
-                #
-                # require:
-                # - one_of: [spec_str, "@:"]
-                RequirementRule(
-                    pkg_name=pkg.name,
-                    policy="one_of",
-                    requirements=[spec, spack.spec.Spec("@:")],
-                    kind=kind,
-                    message=message,
-                    condition=condition,
-                )
-            )
-        return result
-
-    def _parse_prefer_conflict_item(self, item):
-        # The item is either a string or an object with at least a "spec" attribute
-        if isinstance(item, str):
-            spec = parse_spec_from_yaml_string(item)
-            condition = spack.spec.Spec()
-            message = None
-        else:
-            spec = parse_spec_from_yaml_string(item["spec"])
-            condition = spack.spec.Spec(item.get("when"))
-            message = item.get("message")
-        return spec, condition, message
-
-    def _raw_yaml_data(self, pkg: "spack.package_base.PackageBase", *, section: str):
-        config = self.config.get("packages")
-        data = config.get(pkg.name, {}).get(section, [])
-        kind = RequirementKind.PACKAGE
-        if not data:
-            data = config.get("all", {}).get(section, [])
-            kind = RequirementKind.DEFAULT
-        return kind, data
-
-    def _rules_from_requirements(
-        self, pkg_name: str, requirements, *, kind: RequirementKind
-    ) -> List[RequirementRule]:
-        """Manipulate requirements from packages.yaml, and return a list of tuples
-        with a uniform structure (name, policy, requirements).
-        """
-        if isinstance(requirements, str):
-            requirements = [requirements]
-
-        rules = []
-        for requirement in requirements:
-            # A string is equivalent to a one_of group with a single element
-            if isinstance(requirement, str):
-                requirement = {"one_of": [requirement]}
-
-            for policy in ("spec", "one_of", "any_of"):
-                if policy not in requirement:
-                    continue
-
-                constraints = requirement[policy]
-                # "spec" is for specifying a single spec
-                if policy == "spec":
-                    constraints = [constraints]
-                    policy = "one_of"
-
-                # validate specs from YAML first, and fail with line numbers if parsing fails.
-                constraints = [
-                    parse_spec_from_yaml_string(constraint) for constraint in constraints
-                ]
-                when_str = requirement.get("when")
-                when = parse_spec_from_yaml_string(when_str) if when_str else spack.spec.Spec()
-
-                constraints = [
-                    x
-                    for x in constraints
-                    if not self.reject_requirement_constraint(pkg_name, constraint=x, kind=kind)
-                ]
-                if not constraints:
-                    continue
-
-                rules.append(
-                    RequirementRule(
-                        pkg_name=pkg_name,
-                        policy=policy,
-                        requirements=constraints,
-                        kind=kind,
-                        message=requirement.get("message"),
-                        condition=when,
-                    )
-                )
-        return rules
-
-    def reject_requirement_constraint(
-        self, pkg_name: str, *, constraint: spack.spec.Spec, kind: RequirementKind
-    ) -> bool:
-        """Returns True if a requirement constraint should be rejected"""
-        if kind == RequirementKind.DEFAULT:
-            # Requirements under all: are applied only if they are satisfiable considering only
-            # package rules, so e.g. variants must exist etc. Otherwise, they are rejected.
-            try:
-                s = spack.spec.Spec(pkg_name)
-                s.constrain(constraint)
-                s.validate_or_raise()
-            except spack.error.SpackError as e:
-                tty.debug(
-                    f"[SETUP] Rejecting the default '{constraint}' requirement "
-                    f"on '{pkg_name}': {str(e)}",
-                    level=2,
-                )
-                return True
-        return False
-
-
 class CompilerParser:
     """Parses configuration files, and builds a list of possible compilers for the solve."""
 
diff --git a/lib/spack/spack/solver/concretize.lp b/lib/spack/spack/solver/concretize.lp
index 9bb237754e..ebcffa784d 100644
--- a/lib/spack/spack/solver/concretize.lp
+++ b/lib/spack/spack/solver/concretize.lp
@@ -1003,6 +1003,8 @@ variant_default_not_used(node(ID, Package), Variant, Value)
      node_has_variant(node(ID, Package), Variant, _),
      not attr("variant_value", node(ID, Package), Variant, Value),
      not propagate(node(ID, Package), variant_value(Variant, _, _)),
+     % variant set explicitly don't count for this metric
+     not attr("variant_set", node(ID, Package), Variant, _),
      attr("node", node(ID, Package)).
 
 % The variant is set in an external spec
diff --git a/lib/spack/spack/solver/requirements.py b/lib/spack/spack/solver/requirements.py
new file mode 100644
index 0000000000..412f4c22cd
--- /dev/null
+++ b/lib/spack/spack/solver/requirements.py
@@ -0,0 +1,232 @@
+# Copyright 2013-2024 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)
+import enum
+from typing import List, NamedTuple, Optional, Sequence
+
+from llnl.util import tty
+
+import spack.config
+import spack.error
+import spack.package_base
+import spack.spec
+from spack.config import get_mark_from_yaml_data
+
+
+class RequirementKind(enum.Enum):
+    """Purpose / provenance of a requirement"""
+
+    #: Default requirement expressed under the 'all' attribute of packages.yaml
+    DEFAULT = enum.auto()
+    #: Requirement expressed on a virtual package
+    VIRTUAL = enum.auto()
+    #: Requirement expressed on a specific package
+    PACKAGE = enum.auto()
+
+
+class RequirementRule(NamedTuple):
+    """Data class to collect information on a requirement"""
+
+    pkg_name: str
+    policy: str
+    requirements: Sequence[spack.spec.Spec]
+    condition: spack.spec.Spec
+    kind: RequirementKind
+    message: Optional[str]
+
+
+class RequirementParser:
+    """Parses requirements from package.py files and configuration, and returns rules."""
+
+    def __init__(self, configuration: spack.config.Configuration):
+        self.config = configuration
+
+    def rules(self, pkg: spack.package_base.PackageBase) -> List[RequirementRule]:
+        result = []
+        result.extend(self.rules_from_package_py(pkg))
+        result.extend(self.rules_from_require(pkg))
+        result.extend(self.rules_from_prefer(pkg))
+        result.extend(self.rules_from_conflict(pkg))
+        return result
+
+    def rules_from_package_py(self, pkg: spack.package_base.PackageBase) -> List[RequirementRule]:
+        rules = []
+        for when_spec, requirement_list in pkg.requirements.items():
+            for requirements, policy, message in requirement_list:
+                rules.append(
+                    RequirementRule(
+                        pkg_name=pkg.name,
+                        policy=policy,
+                        requirements=requirements,
+                        kind=RequirementKind.PACKAGE,
+                        condition=when_spec,
+                        message=message,
+                    )
+                )
+        return rules
+
+    def rules_from_virtual(self, virtual_str: str) -> List[RequirementRule]:
+        requirements = self.config.get("packages", {}).get(virtual_str, {}).get("require", [])
+        return self._rules_from_requirements(
+            virtual_str, requirements, kind=RequirementKind.VIRTUAL
+        )
+
+    def rules_from_require(self, pkg: spack.package_base.PackageBase) -> List[RequirementRule]:
+        kind, requirements = self._raw_yaml_data(pkg, section="require")
+        return self._rules_from_requirements(pkg.name, requirements, kind=kind)
+
+    def rules_from_prefer(self, pkg: spack.package_base.PackageBase) -> List[RequirementRule]:
+        result = []
+        kind, preferences = self._raw_yaml_data(pkg, section="prefer")
+        for item in preferences:
+            spec, condition, message = self._parse_prefer_conflict_item(item)
+            result.append(
+                # A strong preference is defined as:
+                #
+                # require:
+                # - any_of: [spec_str, "@:"]
+                RequirementRule(
+                    pkg_name=pkg.name,
+                    policy="any_of",
+                    requirements=[spec, spack.spec.Spec("@:")],
+                    kind=kind,
+                    message=message,
+                    condition=condition,
+                )
+            )
+        return result
+
+    def rules_from_conflict(self, pkg: spack.package_base.PackageBase) -> List[RequirementRule]:
+        result = []
+        kind, conflicts = self._raw_yaml_data(pkg, section="conflict")
+        for item in conflicts:
+            spec, condition, message = self._parse_prefer_conflict_item(item)
+            result.append(
+                # A conflict is defined as:
+                #
+                # require:
+                # - one_of: [spec_str, "@:"]
+                RequirementRule(
+                    pkg_name=pkg.name,
+                    policy="one_of",
+                    requirements=[spec, spack.spec.Spec("@:")],
+                    kind=kind,
+                    message=message,
+                    condition=condition,
+                )
+            )
+        return result
+
+    def _parse_prefer_conflict_item(self, item):
+        # The item is either a string or an object with at least a "spec" attribute
+        if isinstance(item, str):
+            spec = parse_spec_from_yaml_string(item)
+            condition = spack.spec.Spec()
+            message = None
+        else:
+            spec = parse_spec_from_yaml_string(item["spec"])
+            condition = spack.spec.Spec(item.get("when"))
+            message = item.get("message")
+        return spec, condition, message
+
+    def _raw_yaml_data(self, pkg: spack.package_base.PackageBase, *, section: str):
+        config = self.config.get("packages")
+        data = config.get(pkg.name, {}).get(section, [])
+        kind = RequirementKind.PACKAGE
+        if not data:
+            data = config.get("all", {}).get(section, [])
+            kind = RequirementKind.DEFAULT
+        return kind, data
+
+    def _rules_from_requirements(
+        self, pkg_name: str, requirements, *, kind: RequirementKind
+    ) -> List[RequirementRule]:
+        """Manipulate requirements from packages.yaml, and return a list of tuples
+        with a uniform structure (name, policy, requirements).
+        """
+        if isinstance(requirements, str):
+            requirements = [requirements]
+
+        rules = []
+        for requirement in requirements:
+            # A string is equivalent to a one_of group with a single element
+            if isinstance(requirement, str):
+                requirement = {"one_of": [requirement]}
+
+            for policy in ("spec", "one_of", "any_of"):
+                if policy not in requirement:
+                    continue
+
+                constraints = requirement[policy]
+                # "spec" is for specifying a single spec
+                if policy == "spec":
+                    constraints = [constraints]
+                    policy = "one_of"
+
+                # validate specs from YAML first, and fail with line numbers if parsing fails.
+                constraints = [
+                    parse_spec_from_yaml_string(constraint) for constraint in constraints
+                ]
+                when_str = requirement.get("when")
+                when = parse_spec_from_yaml_string(when_str) if when_str else spack.spec.Spec()
+
+                constraints = [
+                    x
+                    for x in constraints
+                    if not self.reject_requirement_constraint(pkg_name, constraint=x, kind=kind)
+                ]
+                if not constraints:
+                    continue
+
+                rules.append(
+                    RequirementRule(
+                        pkg_name=pkg_name,
+                        policy=policy,
+                        requirements=constraints,
+                        kind=kind,
+                        message=requirement.get("message"),
+                        condition=when,
+                    )
+                )
+        return rules
+
+    def reject_requirement_constraint(
+        self, pkg_name: str, *, constraint: spack.spec.Spec, kind: RequirementKind
+    ) -> bool:
+        """Returns True if a requirement constraint should be rejected"""
+        if kind == RequirementKind.DEFAULT:
+            # Requirements under all: are applied only if they are satisfiable considering only
+            # package rules, so e.g. variants must exist etc. Otherwise, they are rejected.
+            try:
+                s = spack.spec.Spec(pkg_name)
+                s.constrain(constraint)
+                s.validate_or_raise()
+            except spack.error.SpackError as e:
+                tty.debug(
+                    f"[SETUP] Rejecting the default '{constraint}' requirement "
+                    f"on '{pkg_name}': {str(e)}",
+                    level=2,
+                )
+                return True
+        return False
+
+
+def parse_spec_from_yaml_string(string: str) -> spack.spec.Spec:
+    """Parse a spec from YAML and add file/line info to errors, if it's available.
+
+    Parse a ``Spec`` from the supplied string, but also intercept any syntax errors and
+    add file/line information for debugging using file/line annotations from the string.
+
+    Arguments:
+        string: a string representing a ``Spec`` from config YAML.
+
+    """
+    try:
+        return spack.spec.Spec(string)
+    except spack.error.SpecSyntaxError as e:
+        mark = get_mark_from_yaml_data(string)
+        if mark:
+            msg = f"{mark.name}:{mark.line + 1}: {str(e)}"
+            raise spack.error.SpecSyntaxError(msg) from e
+        raise e