Make uv build fail

Failure test

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

@@ -97,6 +97,10 @@ pub enum Error {
     UnmatchedRuntime(PackageName, PackageName),
     #[error("Build requires for `{0}` missing for metadata declared in `pyproject.toml`")]
     MissingBuildRequirementForMetadata(PackageName),
+    #[error(
+        "Build requirement `{0}` was declared with `match-runtime = true`, but there is no runtime environment to match against"
+    )]
+    UnmatchedRuntimeMetadata(PackageName),
 }
 
 impl IsBuildBackendError for Error {
@@ -114,6 +118,7 @@ impl IsBuildBackendError for Error {
             | Self::NoSourceDistBuilds
             | Self::CyclicBuildDependency(_)
             | Self::UnmatchedRuntime(_, _)
+            | Self::UnmatchedRuntimeMetadata(_)
             | Self::MissingBuildRequirementForMetadata(_) => false,
             Self::CommandFailed(_, _)
             | Self::BuildBackend(_)

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

@@ -404,6 +404,7 @@ impl SourceBuild {
             };
 
             let resolved_requirements = Self::get_resolved_requirements(
+                build_kind,
                 build_context,
                 source_build_context,
                 &DEFAULT_BACKEND,
@@ -528,10 +529,25 @@ impl SourceBuild {
     }
 
     fn apply_build_metadata<'a>(
+        build_kind: BuildKind,
         metadata: &BTreeMap<PackageName, BuildDependencyMetadata>,
         build_requires: impl Iterator<Item = &'a Requirement>,
-        top_level_resolution: &Resolution,
+        build_context: &impl BuildContext,
     ) -> Result<Vec<Requirement>, Box<Error>> {
+        let top_level_resolution = build_context.top_level_resolution();
+        if top_level_resolution.is_none() {
+            for (package, metadata) in metadata {
+                if let Some(true) = metadata.match_runtime {
+                    if !matches!(build_kind, BuildKind::Sdist) {
+                        return Err(Box::new(Error::UnmatchedRuntimeMetadata(package.clone())));
+                    }
+                }
+            }
+            // Nothing needs runtime matching, carry on
+            return Ok(Vec::new());
+        }
+        // SAFETY: check above guarantees that top_level_resolution is Some
+        let top_level_resolution = top_level_resolution.unwrap();
         let dists = top_level_resolution.distributions();
         let dists_by_name = dists
             .filter_map(|dist| metadata.get(dist.name()).map(|_| (dist.name(), dist)))
@@ -578,6 +594,7 @@ impl SourceBuild {
     }
 
     async fn get_resolved_requirements(
+        build_kind: BuildKind,
         build_context: &impl BuildContext,
         source_build_context: SourceBuildContext,
         default_backend: &Pep517Backend,
@@ -622,16 +639,15 @@ impl SourceBuild {
                 };
 
                 if let Some(build_dep_metadata) = build_dep_metadata {
-                    if let Some(resolution) = build_context.top_level_resolution() {
-                        let mut reqs_with_metadata = Self::apply_build_metadata(
-                            &build_dep_metadata.0,
-                            requirements.iter(),
-                            resolution,
-                        )
-                        .map_err(|err| *err)?;
-                        reqs_with_metadata.extend(requirements.into_owned().into_iter());
-                        requirements = Cow::Owned(reqs_with_metadata);
-                    }
+                    let mut reqs_with_metadata = Self::apply_build_metadata(
+                        build_kind,
+                        &build_dep_metadata.0,
+                        requirements.iter(),
+                        build_context,
+                    )
+                    .map_err(|err| *err)?;
+                    reqs_with_metadata.extend(requirements.into_owned().into_iter());
+                    requirements = Cow::Owned(reqs_with_metadata);
                 }
 
                 build_context

crates/uv/tests/it/build.rs

@@ -2084,3 +2084,56 @@ fn venv_included_in_sdist() -> Result<()> {
 
     Ok(())
 }
+
+/// Runtime matching causes building a wheel to fail
+#[test]
+fn runtime_matching() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let project = context.temp_dir.child("project");
+    project
+        .child("src")
+        .child("project")
+        .child("__init__.py")
+        .touch()?;
+    project.child("README").touch()?;
+    let pyproject_toml = project.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+
+        [tool.uv.build-dependencies-metadata.hatchling]
+        match-runtime = true
+
+        [build-system]
+        requires = ["hatchling"]
+        build-backend = "hatchling.build"
+    "#})?;
+
+    uv_snapshot!(context.filters(), context.build().current_dir(&project), @r"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    Building source distribution...
+    Building wheel from source distribution...
+      × Failed to build `[TEMP_DIR]/project`
+      ╰─▶ Build requirement `hatchling` was declared with `match-runtime = true`, but there is no runtime environment to match against
+    ");
+
+    // But building a sdist is fine
+    uv_snapshot!(context.filters(), context.build().arg("--sdist").current_dir(&project), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Building source distribution...
+    Successfully built dist/project-0.1.0.tar.gz
+    ");
+
+    Ok(())
+}

docs/reference/settings.md

@@ -30,6 +30,26 @@ build-constraint-dependencies = ["setuptools==60.0.0"]
 
 ---
 
+### [`build-dependencies-metadata`](#build-dependencies-metadata) {: #build-dependencies-metadata }
+
+Metadata for build dependencies.
+
+This allows specifying metadata for build dependencies, such as runtime matching.
+
+**Default value**: `None`
+
+**Type**: `dict`
+
+**Example usage**:
+
+```toml title="pyproject.toml"
+[tool.uv]
+[build-dependencies-metadata.package1]
+match-runtime = true
+```
+
+---
+
 ### [`conflicts`](#conflicts) {: #conflicts }
 
 Declare collections of extras or dependency groups that are conflicting

uv.schema.json

@@ -46,6 +46,17 @@
         "type": "string"
       }
     },
+    "build-dependencies-metadata": {
+      "description": "Metadata for build dependencies.\n\nThis allows specifying metadata for build dependencies, such as runtime matching.",
+      "anyOf": [
+        {
+          "$ref": "#/definitions/BuildDependenciesMetadata"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
     "cache-dir": {
       "description": "Path to the cache directory.\n\nDefaults to `$XDG_CACHE_HOME/uv` or `$HOME/.cache/uv` on Linux and macOS, and\n`%LOCALAPPDATA%\\uv\\cache` on Windows.",
       "type": [
@@ -759,6 +770,23 @@
         }
       }
     },
+    "BuildDependenciesMetadata": {
+      "type": "object",
+      "additionalProperties": {
+        "$ref": "#/definitions/BuildDependencyMetadata"
+      }
+    },
+    "BuildDependencyMetadata": {
+      "type": "object",
+      "properties": {
+        "match_runtime": {
+          "type": [
+            "boolean",
+            "null"
+          ]
+        }
+      }
+    },
     "CacheKey": {
       "anyOf": [
         {