Simplify supported environments when comparing to lockfile (#7894)

## Summary

If a supported environment includes a Python marker, we don't simplify
it out, despite _storing_ the simplified markers. This PR modifies the
validation code to compare simplified to simplified markers.

Closes https://github.com/astral-sh/uv/issues/7876.

crates/uv-resolver/src/lock/mod.rs

@@ -524,10 +524,17 @@ impl Lock {
     pub fn simplified_supported_environments(&self) -> Vec<MarkerTree> {
         self.supported_environments()
             .iter()
-            .map(|marker| self.requires_python.simplify_markers(marker.clone()))
+            .cloned()
+            .map(|marker| self.simplify_environment(marker))
             .collect()
     }
 
+    /// Simplify the given marker environment with respect to the lockfile's
+    /// `requires-python` setting.
+    pub fn simplify_environment(&self, marker: MarkerTree) -> MarkerTree {
+        self.requires_python.simplify_markers(marker)
+    }
+
     /// If this lockfile was built from a forking resolution with non-identical forks, return the
     /// markers of those forks, otherwise `None`.
     pub fn fork_markers(&self) -> &[MarkerTree] {

crates/uv/src/commands/project/lock.rs

@@ -687,25 +687,6 @@ impl ValidatedLock {
             }
         }
 
-        // If the set of supported environments has changed, we have to perform a clean resolution.
-        if lock.simplified_supported_environments()
-            != environments
-                .map(SupportedEnvironments::as_markers)
-                .unwrap_or_default()
-        {
-            return Ok(Self::Versions(lock));
-        }
-
-        // If the Requires-Python bound has changed, we have to perform a clean resolution, since
-        // the set of `resolution-markers` may no longer cover the entire supported Python range.
-        if lock.requires_python().range() != requires_python.range() {
-            return if lock.fork_markers().is_empty() {
-                Ok(Self::Preferable(lock))
-            } else {
-                Ok(Self::Versions(lock))
-            };
-        }
-
         match upgrade {
             Upgrade::None => {}
             Upgrade::All => {
@@ -716,10 +697,43 @@ impl ValidatedLock {
             Upgrade::Packages(_) => {
                 // If the user specified `--upgrade-package`, then at best we can prefer some of
                 // the existing versions.
+                debug!("Ignoring existing lockfile due to `--upgrade-package`");
                 return Ok(Self::Preferable(lock));
             }
         }
 
+        // If the Requires-Python bound has changed, we have to perform a clean resolution, since
+        // the set of `resolution-markers` may no longer cover the entire supported Python range.
+        if lock.requires_python().range() != requires_python.range() {
+            debug!(
+                "Ignoring existing lockfile due to change in Python requirement: `{}` vs. `{}`",
+                lock.requires_python(),
+                requires_python,
+            );
+            return if lock.fork_markers().is_empty() {
+                Ok(Self::Preferable(lock))
+            } else {
+                Ok(Self::Versions(lock))
+            };
+        }
+
+        // If the set of supported environments has changed, we have to perform a clean resolution.
+        let expected = lock.simplified_supported_environments();
+        let actual = environments
+            .map(SupportedEnvironments::as_markers)
+            .unwrap_or_default()
+            .iter()
+            .cloned()
+            .map(|marker| lock.simplify_environment(marker))
+            .collect::<Vec<_>>();
+        if expected != actual {
+            debug!(
+                "Ignoring existing lockfile due to change in supported environments: `{:?}` vs. `{:?}`",
+                expected, actual
+            );
+            return Ok(Self::Versions(lock));
+        }
+
         // If the user provided at least one index URL (from the command line, or from a configuration
         // file), don't use the existing lockfile if it references any registries that are no longer
         // included in the current configuration.

crates/uv/tests/lock.rs

@@ -12881,6 +12881,117 @@ fn lock_python_upper_bound() -> Result<()> {
     Ok(())
 }
 
+/// See: <https://github.com/astral-sh/uv/issues/7876>
+#[test]
+fn lock_simplified_environments() -> Result<()> {
+    let context = TestContext::new("3.11");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        requires-python = ">=3.11,<3.12"
+        dependencies = ["iniconfig"]
+
+        [tool.uv]
+        environments = [
+            "sys_platform == 'darwin' and python_version >= '3.11' and python_version < '3.12'",
+            "sys_platform != 'darwin' and python_version >= '3.11' and python_version < '3.12'",
+        ]
+        "#,
+    )?;
+
+    uv_snapshot!(context.filters(), context.lock(), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    "###);
+
+    let lock = context.read("uv.lock");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            lock, @r###"
+        version = 1
+        requires-python = "==3.11.*"
+        resolution-markers = [
+            "sys_platform == 'darwin'",
+            "sys_platform != 'darwin'",
+        ]
+        supported-markers = [
+            "sys_platform == 'darwin'",
+            "sys_platform != 'darwin'",
+        ]
+
+        [options]
+        exclude-newer = "2024-03-25T00:00:00Z"
+
+        [[package]]
+        name = "iniconfig"
+        version = "2.0.0"
+        source = { registry = "https://pypi.org/simple" }
+        sdist = { url = "https://files.pythonhosted.org/packages/d7/4b/cbd8e699e64a6f16ca3a8220661b5f83792b3017d0f79807cb8708d33913/iniconfig-2.0.0.tar.gz", hash = "sha256:2d91e135bf72d31a410b17c16da610a82cb55f6b0477d1a902134b24a455b8b3", size = 4646 }
+        wheels = [
+            { url = "https://files.pythonhosted.org/packages/ef/a6/62565a6e1cf69e10f5727360368e451d4b7f58beeac6173dc9db836a5b46/iniconfig-2.0.0-py3-none-any.whl", hash = "sha256:b6a85871a79d2e3b22d2d1b94ac2824226a63c6b741c88f7ae975f18b6778374", size = 5892 },
+        ]
+
+        [[package]]
+        name = "project"
+        version = "0.1.0"
+        source = { virtual = "." }
+        dependencies = [
+            { name = "iniconfig" },
+        ]
+
+        [package.metadata]
+        requires-dist = [{ name = "iniconfig" }]
+        "###
+        );
+    });
+
+    // Re-run with `--locked`.
+    uv_snapshot!(context.filters(), context.lock().arg("--locked"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    "###);
+
+    // Re-run with `--offline`. We shouldn't need a network connection to validate an
+    // already-correct lockfile with immutable metadata.
+    uv_snapshot!(context.filters(), context.lock().arg("--locked").arg("--offline").arg("--no-cache"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    "###);
+
+    // Install from the lockfile.
+    uv_snapshot!(context.filters(), context.sync().arg("--frozen"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + iniconfig==2.0.0
+    "###);
+
+    Ok(())
+}
+
 #[test]
 fn lock_dependency_metadata() -> Result<()> {
     let context = TestContext::new("3.12");