Update description

crates/uv-build-frontend/src/lib.rs

@@ -310,7 +310,6 @@ impl SourceBuild {
             &source_tree,
             install_path,
             fallback_package_name,
-            fallback_package_version,
             locations,
             source_strategy,
             workspace_cache,
@@ -563,7 +562,6 @@ impl SourceBuild {
         source_tree: &Path,
         install_path: &Path,
         package_name: Option<&PackageName>,
-        package_version: Option<&Version>,
         locations: &IndexLocations,
         source_strategy: SourceStrategy,
         workspace_cache: &WorkspaceCache,
@@ -593,6 +591,10 @@ impl SourceBuild {
             Err(err) => return Err(Box::new(err.into())),
         };
 
+        let build_backend = pyproject_toml
+            .build_system
+            .as_ref()
+            .and_then(|build_backend| build_backend.build_backend.as_deref());
         if source_strategy == SourceStrategy::Enabled
             && pyproject_toml
                 .tool
@@ -600,24 +602,24 @@ impl SourceBuild {
                 .and_then(|tool| tool.uv.as_ref())
                 .map(|uv| uv.build_backend.is_some())
                 .unwrap_or(false)
-            && pyproject_toml
-                .build_system
-                .as_ref()
-                .and_then(|build_backend| build_backend.build_backend.as_deref())
-                != Some("uv_build")
+            && build_backend != Some("uv_build")
             && let Some(package_name) =
                 package_name.or(pyproject_toml.project.as_ref().map(|project| &project.name))
-            && let Some(package_version) = package_version.or(pyproject_toml
-                .project
-                .as_ref()
-                .and_then(|project| project.version.as_ref()))
         {
-            // Show name/version where available to avoid showing a (duplicate) warning with
-            // a temporary path.
-            warn_user_once!(
-                "`pyproject.toml` of {package_name}=={package_version} defines settings for \
-                `uv_build` in `tool.uv.build-backend`, but does not use `uv_build`",
-            );
+            // Show only the name, but not the path to `pyproject.toml`, to avoid showing a
+            // (duplicate) warning that contains the temporary path of an unpacked source
+            // distribution in a source tree -> source dist -> wheel build.
+            if let Some(build_backend) = build_backend {
+                warn_user_once!(
+                    "`{package_name}` defines settings for `uv_build` in `tool.uv.build-backend`, \
+                    but uses `{build_backend}` as build backend instead",
+                );
+            } else {
+                warn_user_once!(
+                    "`{package_name}` defines settings for `uv_build` in `tool.uv.build-backend`, \
+                    but the `build-system` table is missing",
+                );
+            }
         }
 
         let backend = if let Some(build_system) = pyproject_toml.build_system {
@@ -640,7 +642,8 @@ impl SourceBuild {
                             locations,
                             source_strategy,
                             workspace_cache,
-                        credentials_cache,)
+                            credentials_cache,
+                        )
                         .await
                         .map_err(Error::Lowering)?;
                         build_requires.requires_dist

crates/uv/tests/it/build_backend.rs

@@ -1249,7 +1249,7 @@ fn tool_uv_build_backend_without_build_backend() -> Result<()> {
 
     ----- stderr -----
     Building source distribution...
-    warning: `pyproject.toml` of project==0.1.0 defines settings for `uv_build` in `tool.uv.build-backend`, but does not use `uv_build`
+    warning: `project` defines settings for `uv_build` in `tool.uv.build-backend`, but the `build-system` table is missing
     Building wheel from source distribution...
     Successfully built dist/project-0.1.0.tar.gz
     Successfully built dist/project-0.1.0-py3-none-any.whl
@@ -1262,7 +1262,7 @@ fn tool_uv_build_backend_without_build_backend() -> Result<()> {
 
     ----- stderr -----
     Resolved 1 package in [TIME]
-    warning: `pyproject.toml` of project==0.1.0 defines settings for `uv_build` in `tool.uv.build-backend`, but does not use `uv_build`
+    warning: `project` defines settings for `uv_build` in `tool.uv.build-backend`, but the `build-system` table is missing
     Prepared 1 package in [TIME]
     Installed 1 package in [TIME]
      + project==0.1.0 (from file://[TEMP_DIR]/)
@@ -1270,3 +1270,57 @@ fn tool_uv_build_backend_without_build_backend() -> Result<()> {
 
     Ok(())
 }
+
+/// Warn for cases where `tool.uv.build-backend` is used without the corresponding build backend
+/// entry.
+#[test]
+fn tool_uv_build_backend_wrong_build_backend() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let project = context.temp_dir.child("project");
+    let pyproject_toml = project.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "project"
+        version = "0.1.0"
+
+        [tool.uv]
+        package = true
+
+        [tool.uv.build-backend.data]
+        data = "assets"
+
+        [build-system]
+        requires = ["hatchling"]
+        build-backend = "hatchling.build"
+    "#})?;
+    project.child("src/project/__init__.py").touch()?;
+
+    uv_snapshot!(context.filters(), context.build().arg("--no-build-logs").arg(project.path()), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Building source distribution...
+    warning: `project` defines settings for `uv_build` in `tool.uv.build-backend`, but uses `hatchling.build` as build backend instead
+    Building wheel from source distribution...
+    Successfully built project/dist/project-0.1.0.tar.gz
+    Successfully built project/dist/project-0.1.0-py2.py3-none-any.whl
+    ");
+
+    uv_snapshot!(context.filters(), context.pip_install().arg(project.path()), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    warning: `project` defines settings for `uv_build` in `tool.uv.build-backend`, but uses `hatchling.build` as build backend instead
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + project==0.1.0 (from file://[TEMP_DIR]/project)
+    ");
+
+    Ok(())
+}