Warn on missing required-features

Co-authored-by: Eric Huss <eric@huss.org>

src/cargo/ops/cargo_compile.rs

@@ -34,7 +34,7 @@ use crate::core::compiler::{DefaultExecutor, Executor, UnitInterner};
 use crate::core::profiles::{Profiles, UnitFor};
 use crate::core::resolver::features::{self, FeaturesFor};
 use crate::core::resolver::{HasDevUnits, Resolve, ResolveOpts};
-use crate::core::{Package, PackageSet, Target};
+use crate::core::{FeatureValue, Package, PackageSet, Shell, Summary, Target};
 use crate::core::{PackageId, PackageIdSpec, TargetKind, Workspace};
 use crate::ops;
 use crate::ops::resolve::WorkspaceResolve;
@@ -417,6 +417,7 @@ pub fn create_bcx<'a, 'cfg>(
         &build_config.requested_kinds,
         build_config.mode,
         &resolve,
+        &workspace_resolve,
         &resolved_features,
         &pkg_set,
         &profiles,
@@ -701,6 +702,7 @@ fn generate_targets(
     requested_kinds: &[CompileKind],
     mode: CompileMode,
     resolve: &Resolve,
+    workspace_resolve: &Option<Resolve>,
     resolved_features: &features::ResolvedFeatures,
     package_set: &PackageSet<'_>,
     profiles: &Profiles,
@@ -929,6 +931,13 @@ fn generate_targets(
     {
         let unavailable_features = match target.required_features() {
             Some(rf) => {
+                warn_on_missing_features(
+                    workspace_resolve,
+                    rf,
+                    pkg.summary(),
+                    &mut config.shell(),
+                )?;
+
                 let features = features_map.entry(pkg).or_insert_with(|| {
                     resolve_all_features(resolve, resolved_features, package_set, pkg.package_id())
                 });
@@ -958,6 +967,68 @@ fn generate_targets(
     Ok(units.into_iter().collect())
 }
 
+fn warn_on_missing_features(
+    resolve: &Option<Resolve>,
+    required_features: &[String],
+    summary: &Summary,
+    shell: &mut Shell,
+) -> CargoResult<()> {
+    let resolve = match resolve {
+        None => return Ok(()),
+        Some(resolve) => resolve,
+    };
+
+    for feature in required_features {
+        match FeatureValue::new(feature.into(), summary) {
+            // No need to do anything here, since the feature must exist to be parsed as such
+            FeatureValue::Feature(_) => {}
+            // Possibly mislabeled feature that was not found
+            FeatureValue::Crate(krate) => {
+                if !summary
+                    .dependencies()
+                    .iter()
+                    .any(|dep| dep.name_in_toml() == krate && dep.is_optional())
+                {
+                    shell.warn(format!(
+                        "feature `{}` is not present in [features] section.",
+                        krate
+                    ))?;
+                }
+            }
+            // Handling of dependent_crate/dependent_crate_feature syntax
+            FeatureValue::CrateFeature(krate, feature) => {
+                match resolve
+                    .deps(summary.package_id())
+                    .find(|(_dep_id, deps)| deps.iter().any(|dep| dep.name_in_toml() == krate))
+                {
+                    Some((dep_id, _deps)) => {
+                        let dep_summary = resolve.summary(dep_id);
+                        if !dep_summary.features().contains_key(&feature)
+                            && !dep_summary
+                                .dependencies()
+                                .iter()
+                                .any(|dep| dep.name_in_toml() == feature && dep.is_optional())
+                        {
+                            shell.warn(format!(
+                                "feature `{}` does not exist in package `{}`.",
+                                feature, dep_id
+                            ))?;
+                        }
+                    }
+                    None => {
+                        shell.warn(format!(
+                            "dependency `{}` specified in required-features as `{}/{}` \
+                             does not exist.",
+                            krate, krate, feature
+                        ))?;
+                    }
+                }
+            }
+        }
+    }
+    Ok(())
+}
+
 /// Gets all of the features enabled for a package, plus its dependencies'
 /// features.
 ///

tests/testsuite/bench.rs

@@ -595,6 +595,9 @@ fn bench_autodiscover_2015() {
                 version = "0.0.1"
                 authors = []
                 edition = "2015"
+                
+                [features]
+                magic = []
 
                 [[bench]]
                 name = "bench_magic"

tests/testsuite/features.rs

@@ -291,7 +291,7 @@ fn invalid9() {
         .build();
 
     p.cargo("build --features bar")
-.with_stderr(
+        .with_stderr(
             "\
 error: Package `foo v0.0.1 ([..])` does not have feature `bar`. It has a required dependency with that name, but only optional dependencies can be used as features.
 ",
@@ -1514,14 +1514,14 @@ fn namespaced_shadowed_dep() {
         .build();
 
     p.cargo("build").masquerade_as_nightly_cargo().with_status(101).with_stderr(
-            "\
+        "\
 [ERROR] failed to parse manifest at `[..]`
 
 Caused by:
   Feature `baz` includes the optional dependency of the same name, but this is left implicit in the features included by this feature.
   Consider adding `crate:baz` to this feature's requirements.
 ",
-        )
+    )
         .run();
 }
 
@@ -1550,15 +1550,15 @@ fn namespaced_shadowed_non_optional() {
         .build();
 
     p.cargo("build").masquerade_as_nightly_cargo().with_status(101).with_stderr(
-            "\
+        "\
 [ERROR] failed to parse manifest at `[..]`
 
 Caused by:
   Feature `baz` includes the dependency of the same name, but this is left implicit in the features included by this feature.
   Additionally, the dependency must be marked as optional to be included in the feature definition.
   Consider adding `crate:baz` to this feature's requirements and marking the dependency as `optional = true`
 ",
-        )
+    )
         .run();
 }
 
@@ -1587,15 +1587,14 @@ fn namespaced_implicit_non_optional() {
         .build();
 
     p.cargo("build").masquerade_as_nightly_cargo().with_status(101).with_stderr(
-            "\
+        "\
 [ERROR] failed to parse manifest at `[..]`
 
 Caused by:
   Feature `bar` includes `baz` which is not defined as a feature.
   A non-optional dependency of the same name is defined; consider adding `optional = true` to its definition
 ",
-        ).run(
-    );
+    ).run();
 }
 
 #[cargo_test]
@@ -2190,3 +2189,47 @@ fn registry_summary_order_doesnt_matter() {
         .with_stdout("it works")
         .run();
 }
+
+#[cargo_test]
+fn nonexistent_required_features() {
+    Package::new("required_dependency", "0.1.0")
+        .feature("simple", &[])
+        .publish();
+    Package::new("optional_dependency", "0.2.0")
+        .feature("optional", &[])
+        .publish();
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+            [project]
+            name = "foo"
+            version = "0.1.0"
+            [features]
+            existing = []
+            fancy = ["optional_dependency"]
+            [dependencies]
+            required_dependency = { version = "0.1", optional = false}
+            optional_dependency = { version = "0.2", optional = true}
+            [[example]]
+            name = "ololo"
+            required-features = ["not_present",
+                                 "existing",
+                                 "fancy",
+                                 "required_dependency/not_existing",
+                                 "required_dependency/simple",
+                                 "optional_dependency/optional",
+                                 "not_specified_dependency/some_feature"]"#,
+        )
+        .file("src/main.rs", "fn main() {}")
+        .file("examples/ololo.rs", "fn main() {}")
+        .build();
+
+    p.cargo("build --examples")
+        .with_stderr_contains(
+            r#"warning: feature `not_present` is not present in [features] section.
+warning: feature `not_existing` does not exist in package `required_dependency v0.1.0`.
+warning: dependency `not_specified_dependency` specified in required-features as `not_specified_dependency/some_feature` does not exist."#,
+        )
+        .run();
+}