fix(bindeps): do not propagate artifact dependency to proc macro or build deps

As reproduced in the 2 fixed test cases of this commit, cargo panicked
when

- a package `foo` has an artifact dependency `artifact` with a specified
  target TARGET_ARTIFACT different from host TARGET_HOST,
- `artifact` depends on proc macro `macro`,
- `macro` conditionally depends on `arch` on TARGET_HOST,

with the following message

```
did not find features for (PackageId { name: "arch", version: "0.0.1", source: "/Users/lencerf/Developer/cargo/target/tmp/cit/t0/foo/arch" }, ArtifactDep(CompileTarget { name: "x86_64-apple-darwin" })) within activated_features:
[
    (
        PackageId {
            name: "foo",
            version: "0.0.1",
            source: "/Users/lencerf/Developer/cargo/target/tmp/cit/t0/foo",
        },
        NormalOrDev,
    ),
    (
        PackageId {
            name: "macro",
            version: "0.0.1",
            source: "/Users/lencerf/Developer/cargo/target/tmp/cit/t0/foo/macro",
        },
        ArtifactDep(
            CompileTarget {
                name: "x86_64-apple-darwin",
            },
        ),
    ),
    (
        PackageId {
            name: "artifact",
            version: "0.0.1",
            source: "/Users/lencerf/Developer/cargo/target/tmp/cit/t0/foo/artifact",
        },
        ArtifactDep(
            CompileTarget {
                name: "x86_64-apple-darwin",
            },
        ),
    ),
]
```

From the above message, it is clear that proc macro `macro` was wrongly
associated with `FeaturesFor::ArtifactDep` instead of
`FeaturesFor::HostDep`. Package `arch` was later ignored because cargo
thought `macro` should be built for TARGET_ARTIFACT
(x86_64-apple-darwin), while `arch` was conditionally needed on
TARGET_HOST (aarch64-apple-darwin).

Similar analyses apply to the other test case.

This commit fixes 2 paths:
- when resolving features, if we encounter build dependencies or proc
  macros, always associate them with `FeaturesFor::HostDep`.
- when deriving UnitFor for dependencies, stop propagating
  artifact_target_for_features if the the dependency is a build
  dependency or a proc macro.

Signed-off-by: Changyuan Lyu <changyuan.lv@gmail.com>

Author: Lencerf

src/cargo/core/profiles.rs

@@ -1180,12 +1180,19 @@ impl UnitFor {
         } else {
             self.panic_setting
         };
+        let artifact_target_for_features =
+            // build.rs and proc-macros are always for host.
+            if dep_target.proc_macro() || parent.target.is_custom_build() {
+                None
+            } else {
+                self.artifact_target_for_features
+            };
         UnitFor {
             host: self.host || dep_for_host,
             host_features,
             panic_setting,
             root_compile_kind,
-            artifact_target_for_features: self.artifact_target_for_features,
+            artifact_target_for_features,
         }
     }
 

src/cargo/core/resolver/features.rs

@@ -906,11 +906,11 @@ impl<'a, 'gctx> FeatureResolver<'a, 'gctx> {
                         // All this may result in a dependency being built multiple times
                         // for various targets which are either specified in the manifest
                         // or on the cargo command-line.
-                        let lib_fk = if fk == FeaturesFor::default() {
-                            (self.track_for_host
-                                && (dep.is_build() || self.has_proc_macro_lib(dep_id)))
-                            .then(|| FeaturesFor::HostDep)
-                            .unwrap_or_default()
+                        let lib_fk = if fk != FeaturesFor::HostDep
+                            && self.track_for_host
+                            && (dep.is_build() || self.has_proc_macro_lib(dep_id))
+                        {
+                            FeaturesFor::HostDep
                         } else {
                             fk
                         };

tests/testsuite/artifact_dep.rs

@@ -3395,11 +3395,10 @@ staticlib present: true
     );
 }
 
-#[should_panic]
 #[cargo_test]
 fn artifact_dep_target_does_not_propagate_to_deps_of_build_script() {
     if cross_compile_disabled() {
-        panic!("panic expected");
+        return;
     }
     let bindeps_target = cross_compile::alternate();
     let native_target = cross_compile::native();
@@ -3486,16 +3485,24 @@ fn artifact_dep_target_does_not_propagate_to_deps_of_build_script() {
         )
         .build();
     p.cargo("test -Z bindeps")
-        .with_stderr_data(str![[""]])
+        .with_stderr_data(str![[r#"
+[LOCKING] 3 packages to latest compatible versions
+[COMPILING] arch v0.0.1 ([ROOT]/foo/arch)
+[COMPILING] builder v0.0.1 ([ROOT]/foo/builder)
+[COMPILING] artifact v0.0.1 ([ROOT]/foo/artifact)
+[COMPILING] foo v0.0.1 ([ROOT]/foo)
+[FINISHED] `test` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+[RUNNING] unittests src/main.rs (target/debug/deps/foo-[HASH][EXE])
+
+"#]])
         .masquerade_as_nightly_cargo(&["bindeps"])
         .run();
 }
 
-#[should_panic]
 #[cargo_test]
 fn artifact_dep_target_does_not_propagate_to_proc_macro() {
     if cross_compile_disabled() {
-        panic!("panic expected");
+        return;
     }
     let bindeps_target = cross_compile::alternate();
     let native_target = cross_compile::native();
@@ -3570,7 +3577,16 @@ fn artifact_dep_target_does_not_propagate_to_proc_macro() {
         )
         .build();
     p.cargo("test -Z bindeps")
-        .with_stderr_data(str![[""]])
+        .with_stderr_data(str![[r#"
+[LOCKING] 3 packages to latest compatible versions
+[COMPILING] arch v0.0.1 ([ROOT]/foo/arch)
+[COMPILING] macro v0.0.1 ([ROOT]/foo/macro)
+[COMPILING] artifact v0.0.1 ([ROOT]/foo/artifact)
+[COMPILING] foo v0.0.1 ([ROOT]/foo)
+[FINISHED] `test` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+[RUNNING] unittests src/main.rs (target/debug/deps/foo-[HASH][EXE])
+
+"#]])
         .masquerade_as_nightly_cargo(&["bindeps"])
         .run();
 }