text: # Copyright 2013-2022 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)
  
  """The variant module contains data structures that are needed to manage
  variants both in packages and in specs.
  """
  
  import functools
  import inspect
  import itertools
  import re
  import sys
  
  from six import StringIO
  
  if sys.version_info >= (3, 5):
      from collections.abc import Sequence  # novm
  else:
      from collections import Sequence
  
  import llnl.util.lang as lang
  import llnl.util.tty.color
  
  import spack.directives
  import spack.error as error
  from spack.util.string import comma_or
  
  special_variant_values = [None, 'none', '*']
  
  
  class Variant(object):
      """Represents a variant in a package, as declared in the
      variant directive.
      """
  
      def __init__(
              self,
              name,
              default,
              description,
              values=(True, False),
              multi=False,
              validator=None):
          """Initialize a package variant.
  
          Args:
              name (str): name of the variant
              default (str): default value for the variant in case
                  nothing has been specified
              description (str): purpose of the variant
              values (sequence): sequence of allowed values or a callable
                  accepting a single value as argument and returning True if the
                  value is good, False otherwise
              multi (bool): whether multiple CSV are allowed
              validator (callable): optional callable used to enforce
                  additional logic on the set of values being validated
          """
          self.name = name
          self.default = default
          self.description = str(description)
  
          self.values = None
          if values == '*':
              # wildcard is a special case to make it easy to say any value is ok
              self.single_value_validator = lambda x: True
  
          elif isinstance(values, type):
              # supplying a type means any value *of that type*
              def isa_type(v):
                  try:
                      values(v)
                      return True
                  except ValueError:
                      return False
              self.single_value_validator = isa_type
  
          if callable(values):
              # If 'values' is a callable, assume it is a single value
              # validator and reset the values to be explicit during debug
              self.single_value_validator = values
  
          else:
              # Otherwise assume values is the set of allowed explicit values
              self.values = values
              self.single_value_validator = lambda x: x in tuple(self.values)
  
          self.multi = multi
          self.group_validator = validator
  
      def validate_or_raise(self, vspec, pkg=None):
          """Validate a variant spec against this package variant. Raises an
          exception if any error is found.
  
          Args:
              vspec (Variant): instance to be validated
              pkg (spack.package.Package): the package that required the validation,
                  if available
  
          Raises:
              InconsistentValidationError: if ``vspec.name != self.name``
  
              MultipleValuesInExclusiveVariantError: if ``vspec`` has
                  multiple values but ``self.multi == False``
  
              InvalidVariantValueError: if ``vspec.value`` contains
                  invalid values
          """
          # Check the name of the variant
          if self.name != vspec.name:
              raise InconsistentValidationError(vspec, self)
  
          # Check the values of the variant spec
          value = vspec.value
          if isinstance(vspec.value, (bool, str)):
              value = (vspec.value,)
  
          # If the value is exclusive there must be at most one
          if not self.multi and len(value) != 1:
              raise MultipleValuesInExclusiveVariantError(vspec, pkg)
  
          # Check and record the values that are not allowed
          not_allowed_values = [
              x for x in value
              if x != '*' and self.single_value_validator(x) is False
          ]
          if not_allowed_values:
              raise InvalidVariantValueError(self, not_allowed_values, pkg)
  
          # Validate the group of values if needed
          if self.group_validator is not None and value != ('*',):
              self.group_validator(pkg.name, self.name, value)
  
      @property
      def allowed_values(self):
          """Returns a string representation of the allowed values for
          printing purposes
  
          Returns:
              str: representation of the allowed values
          """
          # Join an explicit set of allowed values
          if self.values is not None:
              v = tuple(str(x) for x in self.values)
              return ', '.join(v)
          # In case we were given a single-value validator
          # print the docstring
          docstring = inspect.getdoc(self.single_value_validator)
          v = docstring if docstring else ''
          return v
  
      def make_default(self):
          """Factory that creates a variant holding the default value.
  
          Returns:
              MultiValuedVariant or SingleValuedVariant or BoolValuedVariant:
                  instance of the proper variant
          """
          return self.make_variant(self.default)
  
      def make_variant(self, value):
          """Factory that creates a variant holding the value passed as
          a parameter.
  
          Args:
              value: value that will be hold by the variant
  
          Returns:
              MultiValuedVariant or SingleValuedVariant or BoolValuedVariant:
                  instance of the proper variant
          """
          return self.variant_cls(self.name, value)
  
      @property
      def variant_cls(self):
          """Proper variant class to be used for this configuration."""
          if self.multi:
              return MultiValuedVariant
          elif self.values == (True, False):
              return BoolValuedVariant
          return SingleValuedVariant
  
      def __eq__(self, other):
          return (self.name == other.name and
                  self.default == other.default and
                  self.values == other.values and
                  self.multi == other.multi and
                  self.single_value_validator == other.single_value_validator and
                  self.group_validator == other.group_validator)
  
      def __ne__(self, other):
          return not self == other
  
  
  def implicit_variant_conversion(method):
      """Converts other to type(self) and calls method(self, other)
  
      Args:
          method: any predicate method that takes another variant as an argument
  
      Returns: decorated method
      """
      @functools.wraps(method)
      def convert(self, other):
          # We don't care if types are different as long as I can convert
          # other to type(self)
          try:
              other = type(self)(other.name, other._original_value)
          except (error.SpecError, ValueError):
              return False
          return method(self, other)
      return convert
  
  
  @lang.lazy_lexicographic_ordering
  class AbstractVariant(object):
      """A variant that has not yet decided who it wants to be. It behaves like
      a multi valued variant which **could** do things.
  
      This kind of variant is generated during parsing of expressions like
      ``foo=bar`` and differs from multi valued variants because it will
      satisfy any other variant with the same name. This is because it **could**
      do it if it grows up to be a multi valued variant with the right set of
      values.
      """
  
      def __init__(self, name, value):
          self.name = name
  
          # Stores 'value' after a bit of massaging
          # done by the property setter
          self._value = None
          self._original_value = None
  
          # Invokes property setter
          self.value = value
  
      @staticmethod
      def from_node_dict(name, value):
          """Reconstruct a variant from a node dict."""
          if isinstance(value, list):
              # read multi-value variants in and be faithful to the YAML
              mvar = MultiValuedVariant(name, ())
              mvar._value = tuple(value)
              mvar._original_value = mvar._value
              return mvar
  
          elif str(value).upper() == 'TRUE' or str(value).upper() == 'FALSE':
              return BoolValuedVariant(name, value)
  
          return SingleValuedVariant(name, value)
  
      def yaml_entry(self):
          """Returns a key, value tuple suitable to be an entry in a yaml dict.
  
          Returns:
              tuple: (name, value_representation)
          """
          return self.name, list(self.value)
  
      @property
      def value(self):
          """Returns a tuple of strings containing the values stored in
          the variant.
  
          Returns:
              tuple: values stored in the variant
          """
          return self._value
  
      @value.setter
      def value(self, value):
          self._value_setter(value)
  
      def _value_setter(self, value):
          # Store the original value
          self._original_value = value
  
          if not isinstance(value, (tuple, list)):
              # Store a tuple of CSV string representations
              # Tuple is necessary here instead of list because the
              # values need to be hashed
              value = re.split(r'\s*,\s*', str(value))
  
          for val in special_variant_values:
              if val in value and len(value) > 1:
                  msg = "'%s' cannot be combined with other variant" % val
                  msg += " values."
                  raise InvalidVariantValueCombinationError(msg)
  
          # With multi-value variants it is necessary
          # to remove duplicates and give an order
          # to a set
          self._value = tuple(sorted(set(value)))
  
      def _cmp_iter(self):
          yield self.name
  
          value = self._value
          if not isinstance(value, tuple):
              value = (value,)
          value = tuple(str(x) for x in value)
          yield value
  
      def copy(self):
          """Returns an instance of a variant equivalent to self
  
          Returns:
              AbstractVariant: a copy of self
  
          >>> a = MultiValuedVariant('foo', True)
          >>> b = a.copy()
          >>> assert a == b
          >>> assert a is not b
          """
          return type(self)(self.name, self._original_value)
  
      @implicit_variant_conversion
      def satisfies(self, other):
          """Returns true if ``other.name == self.name``, because any value that
          other holds and is not in self yet **could** be added.
  
          Args:
              other: constraint to be met for the method to return True
  
          Returns:
              bool: True or False
          """
          # If names are different then `self` does not satisfy `other`
          # (`foo=bar` will never satisfy `baz=bar`)
          return other.name == self.name
  
      @implicit_variant_conversion
      def compatible(self, other):
          """Returns True if self and other are compatible, False otherwise.
  
          As there is no semantic check, two VariantSpec are compatible if
          either they contain the same value or they are both multi-valued.
  
          Args:
              other: instance against which we test compatibility
  
          Returns:
              bool: True or False
          """
          # If names are different then `self` is not compatible with `other`
          # (`foo=bar` is incompatible with `baz=bar`)
          return other.name == self.name
  
      @implicit_variant_conversion
      def constrain(self, other):
          """Modify self to match all the constraints for other if both
          instances are multi-valued. Returns True if self changed,
          False otherwise.
  
          Args:
              other: instance against which we constrain self
  
          Returns:
              bool: True or False
          """
          if self.name != other.name:
              raise ValueError('variants must have the same name')
  
          old_value = self.value
  
          values = list(sorted(set(self.value + other.value)))
          # If we constraint wildcard by another value, just take value
          if '*' in values and len(values) > 1:
              values.remove('*')
  
          self.value = ','.join(values)
          return old_value != self.value
  
      def __contains__(self, item):
          return item in self._value
  
      def __repr__(self):
          cls = type(self)
          return '{0.__name__}({1}, {2})'.format(
              cls, repr(self.name), repr(self._original_value)
          )
  
      def __str__(self):
          return '{0}={1}'.format(
              self.name, ','.join(str(x) for x in self.value)
          )
  
  
  class MultiValuedVariant(AbstractVariant):
      """A variant that can hold multiple values at once."""
      @implicit_variant_conversion
      def satisfies(self, other):
          """Returns true if ``other.name == self.name`` and ``other.value`` is
          a strict subset of self. Does not try to validate.
  
          Args:
              other: constraint to be met for the method to return True
  
          Returns:
              bool: True or False
          """
          super_sat = super(MultiValuedVariant, self).satisfies(other)
  
          # Otherwise we want all the values in `other` to be also in `self`
          return super_sat and (all(v in self.value for v in other.value) or
                                '*' in other or '*' in self)
  
      def append(self, value):
          """Add another value to this multi-valued variant."""
          self._value = tuple(sorted((value,) + self._value))
          self._original_value = ",".join(self._value)
  
  
  class SingleValuedVariant(AbstractVariant):
      """A variant that can hold multiple values, but one at a time."""
  
      def _value_setter(self, value):
          # Treat the value as a multi-valued variant
          super(SingleValuedVariant, self)._value_setter(value)
  
          # Then check if there's only a single value
          if len(self._value) != 1:
              raise MultipleValuesInExclusiveVariantError(self, None)
          self._value = str(self._value[0])
  
      def __str__(self):
          return '{0}={1}'.format(self.name, self.value)
  
      @implicit_variant_conversion
      def satisfies(self, other):
          abstract_sat = super(SingleValuedVariant, self).satisfies(other)
  
          return abstract_sat and (self.value == other.value or
                                   other.value == '*' or self.value == '*')
  
      def compatible(self, other):
          return self.satisfies(other)
  
      @implicit_variant_conversion
      def constrain(self, other):
          if self.name != other.name:
              raise ValueError('variants must have the same name')
  
          if other.value == '*':
              return False
  
          if self.value == '*':
              self.value = other.value
              return True
  
          if self.value != other.value:
              raise UnsatisfiableVariantSpecError(other.value, self.value)
          return False
  
      def __contains__(self, item):
          return item == self.value
  
      def yaml_entry(self):
          return self.name, self.value
  
  
  class BoolValuedVariant(SingleValuedVariant):
      """A variant that can hold either True or False.
  
      BoolValuedVariant can also hold the value '*', for coerced
      comparisons between ``foo=*`` and ``+foo`` or ``~foo``."""
  
      def _value_setter(self, value):
          # Check the string representation of the value and turn
          # it to a boolean
          if str(value).upper() == 'TRUE':
              self._original_value = value
              self._value = True
          elif str(value).upper() == 'FALSE':
              self._original_value = value
              self._value = False
          elif str(value) == '*':
              self._original_value = value
              self._value = '*'
          else:
              msg = 'cannot construct a BoolValuedVariant for "{0}" from '
              msg += 'a value that does not represent a bool'
              raise ValueError(msg.format(self.name))
  
      def __contains__(self, item):
          return item is self.value
  
      def __str__(self):
          return '{0}{1}'.format('+' if self.value else '~', self.name)
  
  
  class VariantMap(lang.HashableMap):
      """Map containing variant instances. New values can be added only
      if the key is not already present.
      """
  
      def __init__(self, spec):
          super(VariantMap, self).__init__()
          self.spec = spec
  
      def __setitem__(self, name, vspec):
          # Raise a TypeError if vspec is not of the right type
          if not isinstance(vspec, AbstractVariant):
              msg = 'VariantMap accepts only values of variant types'
              msg += ' [got {0} instead]'.format(type(vspec).__name__)
              raise TypeError(msg)
  
          # Raise an error if the variant was already in this map
          if name in self.dict:
              msg = 'Cannot specify variant "{0}" twice'.format(name)
              raise DuplicateVariantError(msg)
  
          # Raise an error if name and vspec.name don't match
          if name != vspec.name:
              msg = 'Inconsistent key "{0}", must be "{1}" to match VariantSpec'
              raise KeyError(msg.format(name, vspec.name))
  
          # Set the item
          super(VariantMap, self).__setitem__(name, vspec)
  
      def substitute(self, vspec):
          """Substitutes the entry under ``vspec.name`` with ``vspec``.
  
          Args:
              vspec: variant spec to be substituted
          """
          if vspec.name not in self:
              msg = 'cannot substitute a key that does not exist [{0}]'
              raise KeyError(msg.format(vspec.name))
  
          # Set the item
          super(VariantMap, self).__setitem__(vspec.name, vspec)
  
      def satisfies(self, other, strict=False):
          """Returns True if this VariantMap is more constrained than other,
          False otherwise.
  
          Args:
              other (VariantMap): VariantMap instance to satisfy
              strict (bool): if True return False if a key is in other and
                  not in self, otherwise discard that key and proceed with
                  evaluation
  
          Returns:
              bool: True or False
          """
          to_be_checked = [k for k in other]
  
          strict_or_concrete = strict
          if self.spec is not None:
              strict_or_concrete |= self.spec._concrete
  
          if not strict_or_concrete:
              to_be_checked = filter(lambda x: x in self, to_be_checked)
  
          return all(k in self and self[k].satisfies(other[k])
                     for k in to_be_checked)
  
      def constrain(self, other):
          """Add all variants in other that aren't in self to self. Also
          constrain all multi-valued variants that are already present.
          Return True if self changed, False otherwise
  
          Args:
              other (VariantMap): instance against which we constrain self
  
          Returns:
              bool: True or False
          """
          if other.spec is not None and other.spec._concrete:
              for k in self:
                  if k not in other:
                      raise UnsatisfiableVariantSpecError(self[k], '<absent>')
  
          changed = False
          for k in other:
              if k in self:
                  # If they are not compatible raise an error
                  if not self[k].compatible(other[k]):
                      raise UnsatisfiableVariantSpecError(self[k], other[k])
                  # If they are compatible merge them
                  changed |= self[k].constrain(other[k])
              else:
                  # If it is not present copy it straight away
                  self[k] = other[k].copy()
                  changed = True
  
          return changed
  
      @property
      def concrete(self):
          """Returns True if the spec is concrete in terms of variants.
  
          Returns:
              bool: True or False
          """
          return self.spec._concrete or all(
              v in self for v in self.spec.package_class.variants
          )
  
      def copy(self):
          """Return an instance of VariantMap equivalent to self.
  
          Returns:
              VariantMap: a copy of self
          """
          clone = VariantMap(self.spec)
          for name, variant in self.items():
              clone[name] = variant.copy()
          return clone
  
      def __str__(self):
          # print keys in order
          sorted_keys = sorted(self.keys())
  
          # Separate boolean variants from key-value pairs as they print
          # differently. All booleans go first to avoid ' ~foo' strings that
          # break spec reuse in zsh.
          bool_keys = []
          kv_keys = []
          for key in sorted_keys:
              bool_keys.append(key) if isinstance(self[key].value, bool) \
                  else kv_keys.append(key)
  
          # add spaces before and after key/value variants.
          string = StringIO()
  
          for key in bool_keys:
              string.write(str(self[key]))
  
          for key in kv_keys:
              string.write(' ')
              string.write(str(self[key]))
  
          return string.getvalue()
  
  
  def substitute_abstract_variants(spec):
      """Uses the information in `spec.package` to turn any variant that needs
      it into a SingleValuedVariant.
  
      This method is best effort. All variants that can be substituted will be
      substituted before any error is raised.
  
      Args:
          spec: spec on which to operate the substitution
      """
      # This method needs to be best effort so that it works in matrix exlusion
      # in $spack/lib/spack/spack/spec_list.py
      failed = []
      for name, v in spec.variants.items():
          if name in spack.directives.reserved_names:
              if name == 'dev_path':
                  new_variant = SingleValuedVariant(name, v._original_value)
                  spec.variants.substitute(new_variant)
              continue
          if name not in spec.package_class.variants:
              failed.append(name)
              continue
          pkg_variant, _ = spec.package_class.variants[name]
          new_variant = pkg_variant.make_variant(v._original_value)
          pkg_variant.validate_or_raise(new_variant, spec.package_class)
          spec.variants.substitute(new_variant)
  
      # Raise all errors at once
      if failed:
          raise UnknownVariantError(spec, failed)
  
  
  # The class below inherit from Sequence to disguise as a tuple and comply
  # with the semantic expected by the 'values' argument of the variant directive
  class DisjointSetsOfValues(Sequence):
      """Allows combinations from one of many mutually exclusive sets.
  
      The value ``('none',)`` is reserved to denote the empty set
      and therefore no other set can contain the item ``'none'``.
  
      Args:
          *sets (list): mutually exclusive sets of values
      """
  
      _empty_set = set(('none',))
  
      def __init__(self, *sets):
          self.sets = [set(x) for x in sets]
  
          # 'none' is a special value and can appear only in a set of
          # a single element
          if any('none' in s and s != set(('none',)) for s in self.sets):
              raise error.SpecError("The value 'none' represents the empty set,"
                                    " and must appear alone in a set. Use the "
                                    "method 'allow_empty_set' to add it.")
  
          # Sets should not intersect with each other
          if any(s1 & s2 for s1, s2 in itertools.combinations(self.sets, 2)):
              raise error.SpecError('sets in input must be disjoint')
  
          #: Attribute used to track values which correspond to
          #: features which can be enabled or disabled as understood by the
          #: package's build system.
          self.feature_values = tuple(itertools.chain.from_iterable(self.sets))
          self.default = None
          self.multi = True
          self.error_fmt = "this variant accepts combinations of values from " \
                           "exactly one of the following sets '{values}' " \
                           "@*r{{[{package}, variant '{variant}']}}"
  
      def with_default(self, default):
          """Sets the default value and returns self."""
          self.default = default
          return self
  
      def with_error(self, error_fmt):
          """Sets the error message format and returns self."""
          self.error_fmt = error_fmt
          return self
  
      def with_non_feature_values(self, *values):
          """Marks a few values as not being tied to a feature."""
          self.feature_values = tuple(
              x for x in self.feature_values if x not in values
          )
          return self
  
      def allow_empty_set(self):
          """Adds the empty set to the current list of disjoint sets."""
          if self._empty_set in self.sets:
              return self
  
          # Create a new object to be returned
          object_with_empty_set = type(self)(('none',), *self.sets)
          object_with_empty_set.error_fmt = self.error_fmt
          object_with_empty_set.feature_values = self.feature_values + ('none', )
          return object_with_empty_set
  
      def prohibit_empty_set(self):
          """Removes the empty set from the current list of disjoint sets."""
          if self._empty_set not in self.sets:
              return self
  
          # Create a new object to be returned
          sets = [s for s in self.sets if s != self._empty_set]
          object_without_empty_set = type(self)(*sets)
          object_without_empty_set.error_fmt = self.error_fmt
          object_without_empty_set.feature_values = tuple(
              x for x in self.feature_values if x != 'none'
          )
          return object_without_empty_set
  
      def __getitem__(self, idx):
          return tuple(itertools.chain.from_iterable(self.sets))[idx]
  
      def __len__(self):
          return len(itertools.chain.from_iterable(self.sets))
  
      @property
      def validator(self):
          def _disjoint_set_validator(pkg_name, variant_name, values):
              # If for any of the sets, all the values are in it return True
              if any(all(x in s for x in values) for s in self.sets):
                  return
  
              format_args = {
                  'variant': variant_name, 'package': pkg_name, 'values': values
              }
              msg = self.error_fmt + \
                  " @*r{{[{package}, variant '{variant}']}}"
              msg = llnl.util.tty.color.colorize(msg.format(**format_args))
              raise error.SpecError(msg)
          return _disjoint_set_validator
  
  
  def _a_single_value_or_a_combination(single_value, *values):
      error = "the value '" + single_value + \
              "' is mutually exclusive with any of the other values"
      return DisjointSetsOfValues(
          (single_value,), values
      ).with_default(single_value).with_error(error).\
          with_non_feature_values(single_value)
  
  
  # TODO: The factories below are used by package writers to set values of
  # TODO: multi-valued variants. It could be worthwhile to gather them in
  # TODO: a common namespace (like 'multi') in the future.
  
  
  def any_combination_of(*values):
      """Multi-valued variant that allows any combination of the specified
      values, and also allows the user to specify 'none' (as a string) to choose
      none of them.
  
      It is up to the package implementation to handle the value 'none'
      specially, if at all.
  
      Args:
          *values: allowed variant values
  
      Returns:
          a properly initialized instance of DisjointSetsOfValues
      """
      return _a_single_value_or_a_combination('none', *values)
  
  
  def auto_or_any_combination_of(*values):
      """Multi-valued variant that allows any combination of a set of values
      (but not the empty set) or 'auto'.
  
      Args:
          *values: allowed variant values
  
      Returns:
          a properly initialized instance of DisjointSetsOfValues
      """
      return _a_single_value_or_a_combination('auto', *values)
  
  
  #: Multi-valued variant that allows any combination picking
  #: from one of multiple disjoint sets
  def disjoint_sets(*sets):
      """Multi-valued variant that allows any combination picking from one
      of multiple disjoint sets of values, and also allows the user to specify
      'none' (as a string) to choose none of them.
  
      It is up to the package implementation to handle the value 'none'
      specially, if at all.
  
      Args:
          *sets:
  
      Returns:
          a properly initialized instance of DisjointSetsOfValues
      """
      return DisjointSetsOfValues(*sets).allow_empty_set().with_default('none')
  
  
  class DuplicateVariantError(error.SpecError):
      """Raised when the same variant occurs in a spec twice."""
  
  
  class UnknownVariantError(error.SpecError):
      """Raised when an unknown variant occurs in a spec."""
      def __init__(self, spec, variants):
          self.unknown_variants = variants
          variant_str = 'variant' if len(variants) == 1 else 'variants'
          msg = ('trying to set {0} "{1}" in package "{2}", but the package'
                 ' has no such {0} [happened during concretization of {3}]')
          msg = msg.format(variant_str, comma_or(variants), spec.name, spec.root)
          super(UnknownVariantError, self).__init__(msg)
  
  
  class InconsistentValidationError(error.SpecError):
      """Raised if the wrong validator is used to validate a variant."""
      def __init__(self, vspec, variant):
          msg = ('trying to validate variant "{0.name}" '
                 'with the validator of "{1.name}"')
          super(InconsistentValidationError, self).__init__(
              msg.format(vspec, variant)
          )
  
  
  class MultipleValuesInExclusiveVariantError(error.SpecError, ValueError):
      """Raised when multiple values are present in a variant that wants
      only one.
      """
      def __init__(self, variant, pkg):
          msg = 'multiple values are not allowed for variant "{0.name}"{1}'
          pkg_info = ''
          if pkg is not None:
              pkg_info = ' in package "{0}"'.format(pkg.name)
          super(MultipleValuesInExclusiveVariantError, self).__init__(
              msg.format(variant, pkg_info)
          )
  
  
  class InvalidVariantValueCombinationError(error.SpecError):
      """Raised when a variant has values '*' or 'none' with other values."""
  
  
  class InvalidVariantValueError(error.SpecError):
      """Raised when a valid variant has at least an invalid value."""
  
      def __init__(self, variant, invalid_values, pkg):
          msg = 'invalid values for variant "{0.name}"{2}: {1}\n'
          pkg_info = ''
          if pkg is not None:
              pkg_info = ' in package "{0}"'.format(pkg.name)
          super(InvalidVariantValueError, self).__init__(
              msg.format(variant, invalid_values, pkg_info)
          )
  
  
  class InvalidVariantForSpecError(error.SpecError):
      """Raised when an invalid conditional variant is specified."""
      def __init__(self, variant, when, spec):
          msg = "Invalid variant {0} for spec {1}.\n"
          msg += "{0} is only available for {1.name} when satisfying one of {2}."
          super(InvalidVariantForSpecError, self).__init__(
              msg.format(variant, spec, when)
          )
  
  
  class UnsatisfiableVariantSpecError(error.UnsatisfiableSpecError):
      """Raised when a spec variant conflicts with package constraints."""
  
      def __init__(self, provided, required):
          super(UnsatisfiableVariantSpecError, self).__init__(
              provided, required, "variant")
  