add setter for version on ProjectPackage

src/poetry/core/packages/package.py

@@ -66,7 +66,6 @@ def __init__(
         """
         Creates a new in memory package.
         """
-        from poetry.core.semver.version import Version
         from poetry.core.version.markers import AnyMarker
 
         super().__init__(
@@ -79,12 +78,7 @@ def __init__(
             features=features,
         )
 
-        if not isinstance(version, Version):
-            self._version = Version.parse(version)
-            self._pretty_version = pretty_version or version
-        else:
-            self._version = version
-            self._pretty_version = pretty_version or self._version.text
+        self._set_version(version, pretty_version)
 
         self.description = ""
 
@@ -216,6 +210,18 @@ def all_requires(
             for dependency in group.dependencies
         ]
 
+    def _set_version(
+        self, version: str | Version, pretty_version: str | None = None
+    ) -> None:
+        from poetry.core.semver.version import Version
+
+        if not isinstance(version, Version):
+            self._version = Version.parse(version)
+            self._pretty_version = pretty_version or version
+        else:
+            self._version = version
+            self._pretty_version = pretty_version or self._version.text
+
     def _get_author(self) -> dict[str, str | None]:
         if not self._authors:
             return {"name": None, "email": None}

src/poetry/core/packages/project_package.py

@@ -63,6 +63,15 @@ def python_versions(self, value: str) -> None:
             create_nested_marker("python_version", self._python_constraint)
         )
 
+    @property
+    def version(self) -> Version:
+        # override version to make it settable
+        return super().version
+
+    @version.setter
+    def version(self, value: str | Version) -> None:
+        self._set_version(value)
+
     @property
     def urls(self) -> dict[str, str]:
         urls = super().urls
@@ -71,5 +80,11 @@ def urls(self) -> dict[str, str]:
 
         return urls
 
+    def __hash__(self) -> int:
+        # The parent Package class's __hash__ incorporates the version because
+        # a Package's version is immutable. But a ProjectPackage's version is
+        # mutable. So call Package's parent hash function.
+        return super(Package, self).__hash__()
+
     def build_should_generate_setup(self) -> bool:
         return self.build_config.get("generate-setup-file", True)

tests/packages/test_package.py

@@ -13,8 +13,10 @@
 from poetry.core.packages.directory_dependency import DirectoryDependency
 from poetry.core.packages.file_dependency import FileDependency
 from poetry.core.packages.package import Package
+from poetry.core.packages.project_package import ProjectPackage
 from poetry.core.packages.url_dependency import URLDependency
 from poetry.core.packages.vcs_dependency import VCSDependency
+from poetry.core.semver.version import Version
 
 
 @pytest.fixture()
@@ -540,3 +542,35 @@ def test_python_versions_are_normalized() -> None:
         == 'python_version > "3.6" and python_version <= "3.10"'
     )
     assert str(package.python_constraint) == ">=3.7,<3.11"
+
+
+def test_cannot_update_package_version() -> None:
+    package = Package("foo", "1.2.3")
+    with pytest.raises(AttributeError):
+        package.version = "1.2.4"  # type: ignore[misc,assignment]
+
+
+def test_project_package_version_update_string() -> None:
+    package = ProjectPackage("foo", "1.2.3")
+    package.version = "1.2.4"  # type: ignore[assignment]
+    assert package.version.text == "1.2.4"
+
+
+def test_project_package_version_update_version() -> None:
+    package = ProjectPackage("foo", "1.2.3")
+    package.version = Version.parse("1.2.4")
+    assert package.version.text == "1.2.4"
+
+
+def test_project_package_hash_not_changed_when_version_is_changed() -> None:
+    package = ProjectPackage("foo", "1.2.3")
+    package_hash = hash(package)
+    package_clone = package.clone()
+    assert package == package_clone
+    assert hash(package) == hash(package_clone)
+
+    package.version = Version.parse("1.2.4")
+
+    assert hash(package) == package_hash, "Hash must not change!"
+    assert hash(package_clone) == package_hash
+    assert package != package_clone