[PEP 771]

src/pip/__init__.py

@@ -1,6 +1,6 @@
 from typing import List, Optional
 
-__version__ = "25.0.dev0"
+__version__ = "25.0.dev0+pep-771"
 
 
 def main(args: Optional[List[str]] = None) -> int:

src/pip/_internal/metadata/_json.py

@@ -30,6 +30,7 @@
     ("Requires-Python", False),
     ("Requires-External", True),
     ("Project-URL", True),
+    ("Default-Extra", True),
     ("Provides-Extra", True),
     ("Provides-Dist", True),
     ("Obsoletes-Dist", True),

src/pip/_internal/metadata/base.py

@@ -442,13 +442,28 @@ def iter_dependencies(self, extras: Collection[str] = ()) -> Iterable[Requiremen
 
         For modern .dist-info distributions, this is the collection of
         "Requires-Dist:" entries in distribution metadata.
+
+        In case, no "Extra" is specified, will use "Default-Extra" as specified
+        per PEP 771.
         """
         raise NotImplementedError()
 
     def iter_raw_dependencies(self) -> Iterable[str]:
         """Raw Requires-Dist metadata."""
         return self.metadata.get_all("Requires-Dist", [])
 
+    def iter_default_extras(self) -> Iterable[NormalizedName]:
+        """Extras provided by this distribution.
+
+        For modern .dist-info distributions, this is the collection of
+        "Default-Extra:" entries in distribution metadata.
+
+        The return value of this function is expected to be normalised names,
+        per PEP 771, with the returned value being handled appropriately by
+        `iter_dependencies`.
+        """
+        raise NotImplementedError()
+
     def iter_provided_extras(self) -> Iterable[NormalizedName]:
         """Extras provided by this distribution.
 

src/pip/_internal/metadata/importlib/_dists.py

@@ -207,13 +207,22 @@ def _metadata_impl(self) -> email.message.Message:
         # until upstream can improve the protocol. (python/cpython#94952)
         return cast(email.message.Message, self._dist.metadata)
 
+    def iter_default_extras(self) -> Iterable[NormalizedName]:
+        return [
+            canonicalize_name(extra)
+            for extra in self.metadata.get_all("Default-Extra", [])
+        ]
+
     def iter_provided_extras(self) -> Iterable[NormalizedName]:
         return [
             canonicalize_name(extra)
             for extra in self.metadata.get_all("Provides-Extra", [])
         ]
 
     def iter_dependencies(self, extras: Collection[str] = ()) -> Iterable[Requirement]:
+        if not extras:
+            extras = list(self.iter_default_extras())
+
         contexts: Sequence[Dict[str, str]] = [{"extra": e} for e in extras]
         for req_string in self.metadata.get_all("Requires-Dist", []):
             # strip() because email.message.Message.get_all() may return a leading \n

src/pip/_internal/metadata/pkg_resources.py

@@ -239,13 +239,19 @@ def _metadata_impl(self) -> email.message.Message:
         return feed_parser.close()
 
     def iter_dependencies(self, extras: Collection[str] = ()) -> Iterable[Requirement]:
+        extras = extras or self._dist.default_extras_require
+
         if extras:
             relevant_extras = set(self._extra_mapping) & set(
                 map(canonicalize_name, extras)
             )
             extras = [self._extra_mapping[extra] for extra in relevant_extras]
+
         return self._dist.requires(extras)
 
+    def iter_default_extras(self) -> Iterable[NormalizedName]:
+        return self._dist.default_extras_require or []
+
     def iter_provided_extras(self) -> Iterable[NormalizedName]:
         return self._extra_mapping.keys()
 

src/pip/_internal/operations/prepare.py

@@ -646,6 +646,12 @@ def _prepare_linked_requirement(
             self.build_isolation,
             self.check_build_deps,
         )
+
+        # Setting up the default-extra if necessary
+        default_extras = frozenset(dist.metadata.get_all("Default-Extra", []))
+        req.extras = req.extras or default_extras
+        req.req.extras = req.extras or default_extras
+
         return dist
 
     def save_linked_requirement(self, req: InstallRequirement) -> None:

src/pip/_internal/req/constructors.py

@@ -31,10 +31,13 @@
 from pip._internal.utils.urls import path_to_url
 from pip._internal.vcs import is_url, vcs
 
+EXPLICIT_EMPTY_EXTRAS = 'explicit-no-default-extras'
+
 __all__ = [
     "install_req_from_editable",
     "install_req_from_line",
     "parse_editable",
+    "EXPLICIT_EMPTY_EXTRAS"
 ]
 
 logger = logging.getLogger(__name__)
@@ -48,7 +51,11 @@ def _strip_extras(path: str) -> Tuple[str, Optional[str]]:
         path_no_extras = m.group(1)
         extras = m.group(2)
     else:
-        path_no_extras = path
+        if '[]' in path:
+            extras = f'[{EXPLICIT_EMPTY_EXTRAS}]'
+            path_no_extras = path.replace('[]', '')
+        else:
+            path_no_extras = path
 
     return path_no_extras, extras
 

src/pip/_internal/resolution/legacy/resolver.py

@@ -38,6 +38,7 @@
     InstallRequirement,
     check_invalid_constraint_type,
 )
+from pip._internal.req.constructors import EXPLICIT_EMPTY_EXTRAS
 from pip._internal.req.req_set import RequirementSet
 from pip._internal.resolution.base import BaseResolver, InstallRequirementProvider
 from pip._internal.utils import compatibility_tags
@@ -552,12 +553,13 @@ def add_req(subreq: Requirement, extras_requested: Iterable[str]) -> None:
                     set(req_to_install.extras) - set(dist.iter_provided_extras())
                 )
                 for missing in missing_requested:
-                    logger.warning(
-                        "%s %s does not provide the extra '%s'",
-                        dist.raw_name,
-                        dist.version,
-                        missing,
-                    )
+                    if missing != EXPLICIT_EMPTY_EXTRAS:
+                        logger.warning(
+                            "%s %s does not provide the extra '%s'",
+                            dist.raw_name,
+                            dist.version,
+                            missing,
+                        )
 
                 available_requested = sorted(
                     set(dist.iter_provided_extras()) & set(req_to_install.extras)

src/pip/_internal/resolution/resolvelib/candidates.py

@@ -21,6 +21,7 @@
     install_req_from_line,
 )
 from pip._internal.req.req_install import InstallRequirement
+from pip._internal.req.constructors import EXPLICIT_EMPTY_EXTRAS
 from pip._internal.utils.direct_url_helpers import direct_url_from_link
 from pip._internal.utils.misc import normalize_version_info
 
@@ -310,6 +311,8 @@ def __init__(
             version=version,
         )
 
+        template.extras = ireq.extras
+
     def _prepare_distribution(self) -> BaseDistribution:
         preparer = self._factory.preparer
         return preparer.prepare_linked_requirement(self._ireq, parallel_builds=True)
@@ -513,12 +516,13 @@ def iter_dependencies(self, with_requires: bool) -> Iterable[Optional[Requiremen
         valid_extras = self.extras.intersection(self.base.dist.iter_provided_extras())
         invalid_extras = self.extras.difference(self.base.dist.iter_provided_extras())
         for extra in sorted(invalid_extras):
-            logger.warning(
-                "%s %s does not provide the extra '%s'",
-                self.base.name,
-                self.version,
-                extra,
-            )
+            if extra != EXPLICIT_EMPTY_EXTRAS:
+                logger.warning(
+                    "%s %s does not provide the extra '%s'",
+                    self.base.name,
+                    self.version,
+                    extra,
+                )
 
         for r in self.base.dist.iter_dependencies(valid_extras):
             yield from factory.make_requirements_from_spec(

src/pip/_internal/resolution/resolvelib/factory.py

@@ -187,6 +187,7 @@ def _make_candidate_from_link(
         base: Optional[BaseCandidate] = self._make_base_candidate_from_link(
             link, template, name, version
         )
+        extras = extras if extras else template.extras
         if not extras or base is None:
             return base
         return self._make_extras_candidate(base, extras, comes_from=template)
@@ -482,6 +483,9 @@ def _make_requirements_from_install_req(
                 (or link) and one with the extra. This allows centralized constraint
                 handling for the base, resulting in fewer candidate rejections.
         """
+        if ireq.comes_from is not None and hasattr(ireq.comes_from, "extra"):
+            requested_extras = requested_extras or ireq.comes_from.extras
+
         if not ireq.match_markers(requested_extras):
             logger.info(
                 "Ignoring %s: markers '%s' don't match your environment",
@@ -504,6 +508,9 @@ def _make_requirements_from_install_req(
                 name=canonicalize_name(ireq.name) if ireq.name else None,
                 version=None,
             )
+
+            extras = ireq.extras or list(cand.dist.iter_default_extras())
+
             if cand is None:
                 # There's no way we can satisfy a URL requirement if the underlying
                 # candidate fails to build. An unnamed URL must be user-supplied, so
@@ -517,10 +524,10 @@ def _make_requirements_from_install_req(
             else:
                 # require the base from the link
                 yield self.make_requirement_from_candidate(cand)
-                if ireq.extras:
+                if extras:
                     # require the extras on top of the base candidate
                     yield self.make_requirement_from_candidate(
-                        self._make_extras_candidate(cand, frozenset(ireq.extras))
+                        self._make_extras_candidate(cand, frozenset(extras))
                     )
 
     def collect_root_requirements(

src/pip/_internal/resolution/resolvelib/requirements.py

@@ -3,7 +3,7 @@
 from pip._vendor.packaging.specifiers import SpecifierSet
 from pip._vendor.packaging.utils import NormalizedName, canonicalize_name
 
-from pip._internal.req.constructors import install_req_drop_extras
+from pip._internal.req.constructors import install_req_drop_extras, EXPLICIT_EMPTY_EXTRAS
 from pip._internal.req.req_install import InstallRequirement
 
 from .base import Candidate, CandidateLookup, Requirement, format_name
@@ -128,6 +128,8 @@ class SpecifierWithoutExtrasRequirement(SpecifierRequirement):
     def __init__(self, ireq: InstallRequirement) -> None:
         assert ireq.link is None, "This is a link, not a specifier"
         self._ireq = install_req_drop_extras(ireq)
+        if ireq.extras:
+            self._ireq.extras = {EXPLICIT_EMPTY_EXTRAS}
         self._equal_cache: Optional[str] = None
         self._hash: Optional[int] = None
         self._extras = frozenset(canonicalize_name(e) for e in self._ireq.extras)

src/pip/_vendor/distlib/metadata.py

@@ -5,7 +5,7 @@
 #
 """Implementation of the Metadata for Python packages PEPs.
 
-Supports all metadata formats (1.0, 1.1, 1.2, 1.3/2.1 and 2.2).
+Supports all metadata formats (1.0, 1.1, 1.2, 1.3/2.1, 2.2, 2.3, 2.4 and 2.5).
 """
 from __future__ import unicode_literals
 
@@ -89,13 +89,20 @@ class MetadataInvalidError(DistlibException):
 
 _643_FIELDS = _566_FIELDS + _643_MARKERS
 
+# PEP 771
+_771_MARKERS = ('Default-Extra')
+
+_771_FIELDS = _643_FIELDS + _771_MARKERS
+
+
 _ALL_FIELDS = set()
 _ALL_FIELDS.update(_241_FIELDS)
 _ALL_FIELDS.update(_314_FIELDS)
 _ALL_FIELDS.update(_345_FIELDS)
 _ALL_FIELDS.update(_426_FIELDS)
 _ALL_FIELDS.update(_566_FIELDS)
 _ALL_FIELDS.update(_643_FIELDS)
+_ALL_FIELDS.update(_771_FIELDS)
 
 EXTRA_RE = re.compile(r'''extra\s*==\s*("([^"]+)"|'([^']+)')''')
 
@@ -115,6 +122,8 @@ def _version2fieldlist(version):
         # return _426_FIELDS
     elif version == '2.2':
         return _643_FIELDS
+    elif version == '2.5':
+        return _771_FIELDS
     raise MetadataUnrecognizedVersionError(version)
 
 
@@ -125,7 +134,7 @@ def _has_marker(keys, markers):
         return any(marker in keys for marker in markers)
 
     keys = [key for key, value in fields.items() if value not in ([], 'UNKNOWN', None)]
-    possible_versions = ['1.0', '1.1', '1.2', '1.3', '2.1', '2.2']  # 2.0 removed
+    possible_versions = ['1.0', '1.1', '1.2', '1.3', '2.1', '2.2', '2.5']  # 2.0 removed
 
     # first let's try to see if a field is not part of one of the version
     for key in keys:
@@ -148,6 +157,9 @@ def _has_marker(keys, markers):
         if key not in _643_FIELDS and '2.2' in possible_versions:
             possible_versions.remove('2.2')
             logger.debug('Removed 2.2 due to %s', key)
+        if key not in _771_FIELDS and '2.5' in possible_versions:
+            possible_versions.remove('2.5')
+            logger.debug('Removed 2.5 due to %s', key)
         # if key not in _426_FIELDS and '2.0' in possible_versions:
         # possible_versions.remove('2.0')
         # logger.debug('Removed 2.0 due to %s', key)
@@ -165,16 +177,19 @@ def _has_marker(keys, markers):
     is_2_1 = '2.1' in possible_versions and _has_marker(keys, _566_MARKERS)
     # is_2_0 = '2.0' in possible_versions and _has_marker(keys, _426_MARKERS)
     is_2_2 = '2.2' in possible_versions and _has_marker(keys, _643_MARKERS)
-    if int(is_1_1) + int(is_1_2) + int(is_2_1) + int(is_2_2) > 1:
-        raise MetadataConflictError('You used incompatible 1.1/1.2/2.1/2.2 fields')
+    is_2_5 = '2.5' in possible_versions and _has_marker(keys, _771_MARKERS)
+
+    if int(is_1_1) + int(is_1_2) + int(is_2_1) + int(is_2_2) + int(is_2_5) > 1:
+        raise MetadataConflictError('You used incompatible 1.1/1.2/2.1/2.2/2.5 fields')
 
     # we have the choice, 1.0, or 1.2, 2.1 or 2.2
     #   - 1.0 has a broken Summary field but works with all tools
     #   - 1.1 is to avoid
     #   - 1.2 fixes Summary but has little adoption
     #   - 2.1 adds more features
-    #   - 2.2 is the latest
-    if not is_1_1 and not is_1_2 and not is_2_1 and not is_2_2:
+    #   - 2.2 adds more features
+    #   - 2.5 is the latest
+    if not is_1_1 and not is_1_2 and not is_2_1 and not is_2_2 and not is_2_5:
         # we couldn't find any specific marker
         if PKG_INFO_PREFERRED_VERSION in possible_versions:
             return PKG_INFO_PREFERRED_VERSION
@@ -184,10 +199,10 @@ def _has_marker(keys, markers):
         return '1.2'
     if is_2_1:
         return '2.1'
-    # if is_2_2:
-    # return '2.2'
+    if is_2_2:
+        return '2.2'
 
-    return '2.2'
+    return '2.5'
 
 
 # This follows the rules about transforming keys as described in

src/pip/_vendor/packaging/metadata.py

@@ -132,6 +132,9 @@ class RawMetadata(TypedDict, total=False):
     license_expression: str
     license_files: list[str]
 
+    # Metadata 2.5 - PEP 771
+    default_extra: list[str]
+
 
 _STRING_FIELDS = {
     "author",
@@ -463,8 +466,8 @@ def parse_email(data: bytes | str) -> tuple[RawMetadata, dict[str, list[str]]]:
 
 
 # Keep the two values in sync.
-_VALID_METADATA_VERSIONS = ["1.0", "1.1", "1.2", "2.1", "2.2", "2.3", "2.4"]
-_MetadataVersion = Literal["1.0", "1.1", "1.2", "2.1", "2.2", "2.3", "2.4"]
+_VALID_METADATA_VERSIONS = ["1.0", "1.1", "1.2", "2.1", "2.2", "2.3", "2.4", "2.5"]
+_MetadataVersion = Literal["1.0", "1.1", "1.2", "2.1", "2.2", "2.3", "2.4", "2.5"]
 
 _REQUIRED_ATTRS = frozenset(["metadata_version", "name", "version"])
 
@@ -861,3 +864,9 @@ def from_email(cls, data: bytes | str, *, validate: bool = True) -> Metadata:
     """``Provides`` (deprecated)"""
     obsoletes: _Validator[list[str] | None] = _Validator(added="1.1")
     """``Obsoletes`` (deprecated)"""
+    # PEP 771 lets us define a default `extras_require` if none is passed by the
+    # user.
+    default_extra: _Validator[list[utils.NormalizedName] | None] = _Validator(
+        added="2.5",
+    )
+    """:external:ref:`core-metadata-default-extra`"""

src/pip/_vendor/pkg_resources/__init__.py

@@ -3070,6 +3070,8 @@ def requires(self, extras: Iterable[str] = ()):
         dm = self._dep_map
         deps: list[Requirement] = []
         deps.extend(dm.get(None, ()))
+
+        extras = extras or self.default_extras_require
         for ext in extras:
             try:
                 deps.extend(dm[safe_extra(ext)])
@@ -3322,6 +3324,10 @@ def clone(self, **kw: str | int | IResourceProvider | None):
     def extras(self):
         return [dep for dep in self._dep_map if dep]
 
+    @property
+    def default_extras_require(self):
+        return self._parsed_pkg_info.get_all('Default-Extra') or []
+
 
 class EggInfoDistribution(Distribution):
     def _reload_version(self):