Pass Install Extras to Markers

docs/dependency-specification.md

@@ -300,6 +300,53 @@ via the `markers` property:
 pathlib2 = { version = "^2.2", markers = "python_version <= '3.4' or sys_platform == 'win32'" }
 ```
 
+### `extra` environment marker
+
+Poetry populates the `extra` marker with each of the selected extras for the parent declaring the dependency. For
+example, consider the following dependency in your root package:
+```toml
+[tool.poetry.dependencies]
+pathlib2 = { version = "^2.2", markers = "extra == 'paths' and sys_platform == 'win32'", optional = true}
+```
+`pathlib2` will be installed when you install your package with `--extras paths` on a `win32` machine.
+You'll also need to [define the `paths` extra in your project](./pyproject.md#extras).
+
+#### Exclusive extras
+
+Keep in mind that all combinations of possible extras available in your project need to be compatible with each other.
+This means that in order to use differing or incompatible versions across different combinations, you need to make your
+extra markers *exclusive*. For example, the following installs PyTorch from one source repository with CPU versions
+when the `cuda` extra is *not* specified, while the other installs from another repository with a separate version set
+for GPUs when the `cuda` extra *is* specified:
+
+```toml
+[tool.poetry.dependencies]
+torch = [
+    { markers = "extra != 'cuda'", version = "2.3.1+cpu", source = "pytorch-cpu", optional = true},
+    { markers = "extra == 'cuda'", version = "2.3.1+cu118", source = "pytorch-cu118", optional = true},
+ ]
+
+[tool.poetry.extras]
+cuda = ["torch"]
+
+[[tool.poetry.source]]
+name = "pytorch-cpu"
+url = "https://download.pytorch.org/whl/cpu"
+priority = "explicit"
+
+[[tool.poetry.source]]
+name = "pytorch-cu118"
+url = "https://download.pytorch.org/whl/cu118"
+priority = "explicit"
+```
+
+For the CPU case, we have to specify `"extra != 'cuda'"` because the version specified is not compatible with the
+GPU (`cuda`) version.
+
+This same logic applies when you want either-or extras. If a dependency for `extra-one` and
+`extra-two` conflict, they will need to be restricted using `markers = "extra == 'extra-one' and extra != 'extra-two'"`
+and vice versa.
+
 ## Multiple constraints dependencies
 
 Sometimes, one of your dependency may have different version ranges depending

src/poetry/installation/installer.py

@@ -287,6 +287,7 @@ def _do_install(self) -> int:
             self._installed_repository.packages,
             locked_repository.packages,
             NullIO(),
+            active_root_extras=self._extras,
         )
         # Everything is resolved at this point, so we no longer need
         # to load deferred dependencies (i.e. VCS, URL and path dependencies)

src/poetry/puzzle/provider.py

@@ -8,6 +8,7 @@
 from collections import defaultdict
 from contextlib import contextmanager
 from typing import TYPE_CHECKING
+from typing import Any
 from typing import ClassVar
 from typing import cast
 
@@ -117,6 +118,7 @@ def __init__(
         *,
         installed: list[Package] | None = None,
         locked: list[Package] | None = None,
+        active_root_extras: Collection[NormalizedName] | None = None,
     ) -> None:
         self._package = package
         self._pool = pool
@@ -133,6 +135,9 @@ def __init__(
         self._direct_origin_packages: dict[str, Package] = {}
         self._locked: dict[NormalizedName, list[DependencyPackage]] = defaultdict(list)
         self._use_latest: Collection[NormalizedName] = []
+        self._active_root_extras = (
+            frozenset(active_root_extras) if active_root_extras is not None else None
+        )
 
         self._explicit_sources: dict[str, str] = {}
         for package in locked or []:
@@ -457,7 +462,16 @@ def incompatibilities_for(
             for dep in dependencies
             if dep.name not in self.UNSAFE_PACKAGES
             and self._python_constraint.allows_any(dep.python_constraint)
-            and (not self._env or dep.marker.validate(self._env.marker_env))
+            and (
+                not self._env
+                or dep.marker.validate(
+                    self._marker_values(
+                        self._active_root_extras
+                        if dependency_package.package.is_root()
+                        else dependency_package.dependency.extras
+                    )
+                )
+            )
         ]
         dependencies = self._get_dependencies_with_overrides(_dependencies, package)
 
@@ -541,7 +555,12 @@ def complete_package(
             if dep.name in self.UNSAFE_PACKAGES:
                 continue
 
-            if self._env and not dep.marker.validate(self._env.marker_env):
+            active_extras = (
+                self._active_root_extras if package.is_root() else dependency.extras
+            )
+            if self._env and not dep.marker.validate(
+                self._marker_values(active_extras)
+            ):
                 continue
 
             if not package.is_root() and (
@@ -601,7 +620,9 @@ def complete_package(
 
             # For dependency resolution, markers of duplicate dependencies must be
             # mutually exclusive.
-            active_extras = None if package.is_root() else dependency.extras
+            active_extras = (
+                self._active_root_extras if package.is_root() else dependency.extras
+            )
             deps = self._resolve_overlapping_markers(package, deps, active_extras)
 
             if len(deps) == 1:
@@ -953,3 +974,17 @@ def _resolve_overlapping_markers(
         # dependencies by constraint again. After overlapping markers were
         # resolved, there might be new dependencies with the same constraint.
         return self._merge_dependencies_by_constraint(new_dependencies)
+
+    def _marker_values(
+        self, extras: Collection[NormalizedName] | None = None
+    ) -> dict[str, Any]:
+        """
+        Marker values, from `self._env` if present plus the supplied extras
+
+        :param extras: the values to add to the 'extra' marker value
+        """
+        result = self._env.marker_env.copy() if self._env is not None else {}
+        if extras is not None:
+            assert "extra" not in result, "'extra' marker key is already present in environment"
+            result["extra"] = set(extras)
+        return result

src/poetry/puzzle/solver.py

@@ -41,6 +41,7 @@
         installed: list[Package],
         locked: list[Package],
         io: IO,
+        active_root_extras: Collection[NormalizedName] | None = None,
     ) -> None:
         self._package = package
         self._pool = pool
@@ -49,7 +50,12 @@
         self._io = io
 
         self._provider = Provider(
-            self._package, self._pool, self._io, installed=installed, locked=locked
+            self._package,
+            self._pool,
+            self._io,
+            installed=installed,
+            locked=locked,
+            active_root_extras=active_root_extras,
         )
         self._overrides: list[dict[Package, dict[str, Dependency]]] = []
 
@@ -152,7 +158,7 @@
             self._overrides.append(self._provider._overrides)
 
         try:
             result = resolve_version(self._package, self._provider)
 
             packages = result.packages
         except OverrideNeeded as e:

tests/installation/fixtures/with-conflicting-dependencies-root-extras.test

@@ -0,0 +1,24 @@
+[[package]]
+name = "dependency"
+version = "1.1.0"
+description = ""
+optional = true
+python-versions = "*"
+files = []
+
+[[package]]
+name = "dependency"
+version = "1.2.0"
+description = ""
+optional = true
+python-versions = "*"
+files = []
+
+[extras]
+extra-one = ["dependency"]
+extra-two = ["dependency"]
+
+[metadata]
+python-versions = "*"
+lock-version = "2.0"
+content-hash = "123456789"

tests/installation/fixtures/with-dependencies-differing-extras.test

@@ -0,0 +1,40 @@
+[[package]]
+name = "demo"
+version = "1.0.0"
+description = ""
+optional = true
+python-versions = "*"
+files = []
+
+[package.extras]
+demo-extra-one = ["transitive-dep-one"]
+demo-extra-two = ["transitive-dep-two"]
+
+[package.dependencies]
+transitive-dep-one = {version = "1.1.0", optional = true}
+transitive-dep-two = {version = "1.2.0", optional = true}
+
+[[package]]
+name = "transitive-dep-one"
+version = "1.1.0"
+description = ""
+optional = true
+python-versions = "*"
+files = []
+
+[[package]]
+name = "transitive-dep-two"
+version = "1.2.0"
+description = ""
+optional = true
+python-versions = "*"
+files = []
+
+[extras]
+extra-one = ["demo", "demo"]
+extra-two = ["demo", "demo"]
+
+[metadata]
+python-versions = "*"
+lock-version = "2.0"
+content-hash = "123456789"

tests/installation/fixtures/with-exclusive-extras.test

@@ -0,0 +1,34 @@
+[[package]]
+name = "torch"
+version = "1.11.0+cpu"
+description = ""
+optional = true
+python-versions = "*"
+files = []
+
+[package.source]
+reference = "pytorch-cpu"
+type = "legacy"
+url = "https://download.pytorch.org/whl/cpu"
+
+[[package]]
+name = "torch"
+version = "1.11.0+cuda"
+description = ""
+optional = true
+python-versions = "*"
+files = []
+
+[package.source]
+reference = "pytorch-cuda"
+type = "legacy"
+url = "https://download.pytorch.org/whl/cuda"
+
+[extras]
+cpu = ["torch", "torch"]
+cuda = ["torch", "torch"]
+
+[metadata]
+python-versions = "*"
+lock-version = "2.0"
+content-hash = "123456789"