Respect self-constraints on recursive extras (#9714)

## Summary

Sort of ridiculous, but today this passes, when it should fail:

```toml
[project]
name = "foo"
version = "0.1.0"
description = "Add your description here"
readme = "README.md"
requires-python = ">=3.13.0"
dependencies = []

[project.optional-dependencies]
async = [
    "foo[async]==0.2.0",
]
```

crates/uv-pypi-types/src/requirement.rs

@@ -562,6 +562,16 @@ impl RequirementSource {
         matches!(self, Self::Directory { editable: true, .. })
     }
 
+    /// Returns `true` if the source is empty.
+    pub fn is_empty(&self) -> bool {
+        match self {
+            Self::Registry { specifier, .. } => specifier.is_empty(),
+            Self::Url { .. } | Self::Git { .. } | Self::Path { .. } | Self::Directory { .. } => {
+                false
+            }
+        }
+    }
+
     /// If the source is the registry, return the version specifiers
     pub fn version_specifiers(&self) -> Option<&VersionSpecifiers> {
         match self {

crates/uv-resolver/src/pubgrub/report.rs

@@ -1328,7 +1328,7 @@ impl std::fmt::Display for PubGrubHint {
             Self::DependsOnItself { package } => {
                 write!(
                     f,
-                    "{}{} The package `{}` depends on itself. This is likely a mistake. Consider removing the dependency.",
+                    "{}{} The package `{}` depends on itself at an incompatible version. This is likely a mistake. Consider removing the dependency.",
                     "hint".bold().cyan(),
                     ":".bold(),
                     package.cyan(),

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

@@ -1567,7 +1567,8 @@ impl<InstalledPackages: InstalledPackagesProvider> ResolverState<InstalledPackag
             return requirements;
         }
 
-        // Check if there are recursive self inclusions and we need to go into the expensive branch.
+        // Check if there are recursive self inclusions; if so, we need to go into the expensive
+        // branch.
         if !requirements
             .iter()
             .any(|req| name == Some(&req.name) && !req.extras.is_empty())
@@ -1624,8 +1625,26 @@ impl<InstalledPackages: InstalledPackagesProvider> ResolverState<InstalledPackag
             }
         }
 
+        // Retain any self-constraints for that extra, e.g., if `project[foo]` includes
+        // `project[bar]>1.0`, as a dependency, we need to propagate `project>1.0`, in addition to
+        // transitively expanding `project[bar]`.
+        let mut self_constraints = vec![];
+        for req in &requirements {
+            if name == Some(&req.name) && !req.source.is_empty() {
+                self_constraints.push(Requirement {
+                    name: req.name.clone(),
+                    extras: vec![],
+                    groups: req.groups.clone(),
+                    source: req.source.clone(),
+                    origin: req.origin.clone(),
+                    marker: req.marker,
+                });
+            }
+        }
+
         // Drop all the self-requirements now that we flattened them out.
-        requirements.retain(|req| name != Some(&req.name));
+        requirements.retain(|req| name != Some(&req.name) || req.extras.is_empty());
+        requirements.extend(self_constraints.into_iter().map(Cow::Owned));
 
         requirements
     }

crates/uv/tests/it/lock.rs

@@ -19457,7 +19457,7 @@ fn lock_self_incompatible() -> Result<()> {
       × No solution found when resolving dependencies:
       ╰─▶ Because your project depends on itself at an incompatible version (project==0.2.0), we can conclude that your project's requirements are unsatisfiable.
 
-          hint: The package `project` depends on itself. This is likely a mistake. Consider removing the dependency.
+          hint: The package `project` depends on itself at an incompatible version. This is likely a mistake. Consider removing the dependency.
     "###);
 
     Ok(())
@@ -19566,10 +19566,9 @@ fn lock_self_extra_to_extra_compatible() -> Result<()> {
 }
 
 #[test]
-fn lock_self_extra_to_extra_incompatible() -> Result<()> {
+fn lock_self_extra_to_same_extra_incompatible() -> Result<()> {
     let context = TestContext::new("3.12");
 
-    // TODO(charlie): This should fail, but currently succeeds.
     let pyproject_toml = context.temp_dir.child("pyproject.toml");
     pyproject_toml.write_str(
         r#"
@@ -19585,52 +19584,50 @@ fn lock_self_extra_to_extra_incompatible() -> Result<()> {
     )?;
 
     uv_snapshot!(context.filters(), context.lock(), @r###"
-    success: true
-    exit_code: 0
+    success: false
+    exit_code: 1
     ----- stdout -----
 
     ----- stderr -----
-    Resolved 2 packages in [TIME]
-    "###);
+      × No solution found when resolving dependencies:
+      ╰─▶ Because project[foo] depends on your project and your project requires project[foo], we can conclude that your project's requirements are unsatisfiable.
 
-    let lock = context.read("uv.lock");
+          hint: The package `project[foo]` depends on itself at an incompatible version. This is likely a mistake. Consider removing the dependency.
+    "###);
 
-    insta::with_settings!({
-        filters => context.filters(),
-    }, {
-        assert_snapshot!(
-            lock, @r###"
-        version = 1
-        requires-python = ">=3.12"
+    Ok(())
+}
 
-        [options]
-        exclude-newer = "2024-03-25T00:00:00Z"
+#[test]
+fn lock_self_extra_to_other_extra_incompatible() -> Result<()> {
+    let context = TestContext::new("3.12");
 
-        [[package]]
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
         name = "project"
         version = "0.1.0"
-        source = { virtual = "." }
-        dependencies = [
-            { name = "typing-extensions" },
-        ]
+        requires-python = ">=3.12"
+        dependencies = ["typing-extensions"]
 
-        [package.metadata]
-        requires-dist = [
-            { name = "project", extras = ["foo"], marker = "extra == 'foo'", specifier = "==0.2.0" },
-            { name = "typing-extensions" },
-        ]
+        [project.optional-dependencies]
+        foo = ["project[bar]==0.2.0"]
+        bar = ["iniconfig"]
+        "#,
+    )?;
 
-        [[package]]
-        name = "typing-extensions"
-        version = "4.10.0"
-        source = { registry = "https://pypi.org/simple" }
-        sdist = { url = "https://files.pythonhosted.org/packages/16/3a/0d26ce356c7465a19c9ea8814b960f8a36c3b0d07c323176620b7b483e44/typing_extensions-4.10.0.tar.gz", hash = "sha256:b0abd7c89e8fb96f98db18d86106ff1d90ab692004eb746cf6eda2682f91b3cb", size = 77558 }
-        wheels = [
-            { url = "https://files.pythonhosted.org/packages/f9/de/dc04a3ea60b22624b51c703a84bbe0184abcd1d0b9bc8074b5d6b7ab90bb/typing_extensions-4.10.0-py3-none-any.whl", hash = "sha256:69b1a937c3a517342112fb4c6df7e72fc39a38e7891a5730ed4985b5214b5475", size = 33926 },
-        ]
-        "###
-        );
-    });
+    uv_snapshot!(context.filters(), context.lock(), @r###"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+      × No solution found when resolving dependencies:
+      ╰─▶ Because project[foo] depends on your project and your project requires project[foo], we can conclude that your project's requirements are unsatisfiable.
+
+          hint: The package `project[foo]` depends on itself at an incompatible version. This is likely a mistake. Consider removing the dependency.
+    "###);
 
     Ok(())
 }
@@ -19764,7 +19761,7 @@ fn lock_self_extra_incompatible() -> Result<()> {
       × No solution found when resolving dependencies:
       ╰─▶ Because project[foo] depends on your project and your project requires project[foo], we can conclude that your project's requirements are unsatisfiable.
 
-          hint: The package `project[foo]` depends on itself. This is likely a mistake. Consider removing the dependency.
+          hint: The package `project[foo]` depends on itself at an incompatible version. This is likely a mistake. Consider removing the dependency.
     "###);
 
     Ok(())
@@ -19893,7 +19890,7 @@ fn lock_self_marker_incompatible() -> Result<()> {
       × No solution found when resolving dependencies:
       ╰─▶ Because only project{sys_platform == 'win32'}<=0.1 is available and your project depends on project{sys_platform == 'win32'}>0.1, we can conclude that your project's requirements are unsatisfiable.
 
-          hint: The package `project` depends on itself. This is likely a mistake. Consider removing the dependency.
+          hint: The package `project` depends on itself at an incompatible version. This is likely a mistake. Consider removing the dependency.
     "###);
 
     Ok(())