Look at FeaturesFor:: to decide if a dependency participates in feature resolution

Fixes #10431.

src/cargo/core/resolver/features.rs

@@ -769,6 +769,12 @@ impl<'a, 'cfg> FeatureResolver<'a, 'cfg> {
                     .target_data
                     .dep_platform_activated(dep, CompileKind::Host);
             }
+            // We always count platforms as activated if the target stems from an artifact
+            // dependency's target specification. This triggers in conjunction with
+            // `[target.'cfg(…)'.dependencies]` manifest sections.
+            if matches!(fk, FeaturesFor::NormalOrDevOrArtifactTarget(Some(_))) {
+                return true;
+            }
             // Not a build dependency, and not for a build script, so must be Target.
             self.requested_targets
                 .iter()

tests/testsuite/artifact_dep.rs

@@ -426,7 +426,6 @@ fn features_are_not_unified_among_lib_and_bin_dep_of_different_target() {
 }
 
 #[cargo_test]
-#[ignore]
 fn feature_resolution_works_for_cfg_target_specification() {
     if cross_compile::disabled() {
         return;