Error when direct URL requirements don't match Requires-Python

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

@@ -17,7 +17,6 @@ use tokio_stream::wrappers::ReceiverStream;
 use tracing::{debug, info_span, instrument, trace, warn, Instrument};
 use url::Url;
 
-use distribution_filename::WheelFilename;
 use distribution_types::{
     BuiltDist, Dist, DistributionMetadata, IncompatibleWheel, Name, RemoteSource, SourceDist,
     VersionOrUrl,
@@ -569,38 +568,53 @@ impl<'a, Provider: ResolverProvider> Resolver<'a, Provider> {
 
                 // If the dist is an editable, return the version from the editable metadata.
                 if let Some((_local, metadata)) = self.editables.get(package_name) {
-                    let version = metadata.version.clone();
-                    return if range.contains(&version) {
-                        Ok(Some(ResolverVersion::Available(version)))
-                    } else {
-                        Ok(None)
-                    };
-                }
+                    let version = &metadata.version;
 
-                if let Ok(wheel_filename) = WheelFilename::try_from(url.raw()) {
-                    // If the URL is that of a wheel, extract the version.
-                    let version = wheel_filename.version;
-                    if range.contains(&version) {
-                        Ok(Some(ResolverVersion::Available(version)))
-                    } else {
-                        Ok(None)
+                    // The version is incompatible with the requirement.
+                    if !range.contains(version) {
+                        return Ok(None);
                     }
-                } else {
-                    // Otherwise, assume this is a source distribution.
-                    let dist = PubGrubDistribution::from_url(package_name, url);
-                    let metadata = self
-                        .index
-                        .distributions
-                        .wait(&dist.package_id())
-                        .await
-                        .ok_or(ResolveError::Unregistered)?;
-                    let version = &metadata.version;
-                    if range.contains(version) {
-                        Ok(Some(ResolverVersion::Available(version.clone())))
-                    } else {
-                        Ok(None)
+
+                    // The version is incompatible due to its Python requirement.
+                    if let Some(requires_python) = metadata.requires_python.as_ref() {
+                        let target = self.python_requirement.target();
+                        if !requires_python.contains(target) {
+                            return Ok(Some(ResolverVersion::Unavailable(
+                                version.clone(),
+                                UnavailableVersion::RequiresPython(requires_python.clone()),
+                            )));
+                        }
+                    }
+
+                    return Ok(Some(ResolverVersion::Available(version.clone())));
+                }
+
+                let dist = PubGrubDistribution::from_url(package_name, url);
+                let metadata = self
+                    .index
+                    .distributions
+                    .wait(&dist.package_id())
+                    .await
+                    .ok_or(ResolveError::Unregistered)?;
+                let version = &metadata.version;
+
+                // The version is incompatible with the requirement.
+                if !range.contains(version) {
+                    return Ok(None);
+                }
+
+                // The version is incompatible due to its Python requirement.
+                if let Some(requires_python) = metadata.requires_python.as_ref() {
+                    let target = self.python_requirement.target();
+                    if !requires_python.contains(target) {
+                        return Ok(Some(ResolverVersion::Unavailable(
+                            version.clone(),
+                            UnavailableVersion::RequiresPython(requires_python.clone()),
+                        )));
                     }
                 }
+
+                Ok(Some(ResolverVersion::Available(version.clone())))
             }
 
             PubGrubPackage::Package(package_name, extra, None) => {

crates/uv/tests/pip_compile.rs

@@ -4756,3 +4756,45 @@ requires-python = "<=3.8"
 
     Ok(())
 }
+
+/// Raise an error when a direct URL dependency's `Requires-Python` constraint is not met.
+#[test]
+fn requires_python_direct_url() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    // Create an editable package with a `Requires-Python` constraint that is not met.
+    let editable_dir = TempDir::new()?;
+    let pyproject_toml = editable_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"[project]
+name = "example"
+version = "0.0.0"
+dependencies = [
+  "anyio==4.0.0"
+]
+requires-python = "<=3.8"
+"#,
+    )?;
+
+    // Write to a requirements file.
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str(&format!("example @ {}", editable_dir.path().display()))?;
+
+    uv_snapshot!(context.compile()
+        .arg("requirements.in"), @r###"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+      × No solution found when resolving dependencies:
+      ╰─▶ Because the current Python version (3.12.1) does not satisfy Python<=3.8
+          and example==0.0.0 depends on Python<=3.8, we can conclude that
+          example==0.0.0 cannot be used.
+          And because only example==0.0.0 is available and you require example, we
+          can conclude that the requirements are unsatisfiable.
+    "###
+    );
+
+    Ok(())
+}

crates/uv/tests/pip_install.rs

@@ -2281,3 +2281,41 @@ requires-python = "<=3.8"
 
     Ok(())
 }
+
+/// Raise an error when a direct URL's `Requires-Python` constraint is not met.
+#[test]
+fn requires_python_direct_url() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    // Create an editable package with a `Requires-Python` constraint that is not met.
+    let editable_dir = assert_fs::TempDir::new()?;
+    let pyproject_toml = editable_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"[project]
+name = "example"
+version = "0.0.0"
+dependencies = [
+  "anyio==4.0.0"
+]
+requires-python = "<=3.8"
+"#,
+    )?;
+
+    uv_snapshot!(command(&context)
+        .arg(format!("example @ {}", editable_dir.path().display())), @r###"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+      × No solution found when resolving dependencies:
+      ╰─▶ Because the current Python version (3.12.1) does not satisfy Python<=3.8
+          and example==0.0.0 depends on Python<=3.8, we can conclude that
+          example==0.0.0 cannot be used.
+          And because only example==0.0.0 is available and you require example, we
+          can conclude that the requirements are unsatisfiable.
+    "###
+    );
+
+    Ok(())
+}

crates/uv/tests/pip_sync.rs

@@ -2993,3 +2993,51 @@ requires-python = "<=3.5"
 
     Ok(())
 }
+
+/// Raise an error when a direct URL dependency's `Requires-Python` constraint is not met.
+///
+/// TODO(charlie): This currently passes, but should fail.
+#[test]
+fn requires_python_direct_url() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    // Create an editable package with a `Requires-Python` constraint that is not met.
+    let editable_dir = assert_fs::TempDir::new()?;
+    let pyproject_toml = editable_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"[project]
+name = "example"
+version = "0.0.0"
+dependencies = [
+  "anyio==4.0.0"
+]
+requires-python = "<=3.5"
+"#,
+    )?;
+
+    // Write to a requirements file.
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str(&format!("example @ {}", editable_dir.path().display()))?;
+
+    // In addition to the standard filters, remove the temporary directory from the snapshot.
+    let filters: Vec<_> = [(r"\(from file://.*\)", "(from file://[TEMP_DIR])")]
+        .into_iter()
+        .chain(INSTA_FILTERS.to_vec())
+        .collect();
+
+    uv_snapshot!(filters, command(&context)
+        .arg("requirements.in"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    Downloaded 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + example==0.0.0 (from file://[TEMP_DIR])
+    "###
+    );
+
+    Ok(())
+}