[BETA] Fix cargo rustc for test with implicit binary.

src/cargo/core/compiler/context/unit_dependencies.rs

@@ -148,6 +148,46 @@ fn compute_deps<'a, 'b, 'cfg>(
     }
     ret.extend(maybe_lib(unit, bcx, profile_for));
 
+    // If any integration tests/benches are being run, make sure that
+    // binaries are built as well.
+    if !unit.mode.is_check() && unit.mode.is_any_test()
+        && (unit.target.is_test() || unit.target.is_bench())
+    {
+        ret.extend(
+            unit.pkg
+                .targets()
+                .iter()
+                .filter(|t| {
+                    let no_required_features = Vec::new();
+
+                    t.is_bin() &&
+                        // Skip binaries with required features that have not been selected.
+                        t.required_features().unwrap_or(&no_required_features).iter().all(|f| {
+                            bcx.resolve.features(id).contains(f)
+                        })
+                })
+                .map(|t| {
+                    (
+                        // TODO: Should not be using profile_for here. Should
+                        // instead use ProfileFor::Any so that bins are built
+                        // with panic, but this aggravates
+                        // https://github.com/rust-lang/cargo/issues/5444
+                        // Switching it will fix
+                        // https://github.com/rust-lang/cargo/issues/5435
+                        new_unit(
+                            bcx,
+                            unit.pkg,
+                            t,
+                            profile_for,
+                            unit.kind.for_target(t),
+                            CompileMode::Build,
+                        ),
+                        profile_for,
+                    )
+                }),
+        );
+    }
+
     Ok(ret)
 }
 

src/cargo/ops/cargo_compile.rs

@@ -615,19 +615,6 @@ fn generate_targets<'a>(
             }
         }
 
-        // If any integration tests/benches are being run, make sure that
-        // binaries are built as well.
-        if !build_config.mode.is_check() && proposals.iter().any(|&(ref unit, _)| {
-            unit.mode.is_any_test() && (unit.target.is_test() || unit.target.is_bench())
-        }) {
-            proposals.extend(
-                pkg.targets()
-                    .iter()
-                    .filter(|t| t.is_bin())
-                    .map(|t| (new_unit(pkg, t, CompileMode::Build), false)),
-            );
-        }
-
         // Only include targets that are libraries or have all required
         // features available.
         for (unit, required) in proposals {

tests/testsuite/rustc.rs

@@ -1,4 +1,4 @@
-use cargotest::support::{basic_lib_manifest, execs, project};
+use cargotest::support::{basic_bin_manifest, basic_lib_manifest, execs, project};
 use hamcrest::assert_that;
 
 const CARGO_RUSTC_ERROR: &'static str =
@@ -649,3 +649,40 @@ fn rustc_fingerprint() {
         ),
     );
 }
+
+#[test]
+fn rustc_test_with_implicit_bin() {
+    let p = project("foo")
+        .file("Cargo.toml", &basic_bin_manifest("foo"))
+        .file(
+            "src/main.rs",
+            r#"
+            #[cfg(foo)]
+            fn f() { compile_fail!("Foo shouldn't be set."); }
+            fn main() {}
+        "#,
+        )
+        .file(
+            "tests/test1.rs",
+            r#"
+            #[cfg(not(foo))]
+            fn f() { compile_fail!("Foo should be set."); } "#,
+        )
+        .build();
+
+    assert_that(
+        p.cargo("rustc --test test1 -v -- --cfg foo"),
+        execs()
+            .with_status(0)
+            .with_stderr_contains(
+                "\
+[RUNNING] `rustc --crate-name test1 tests[/]test1.rs [..] --cfg foo [..]
+",
+            )
+            .with_stderr_contains(
+                "\
+[RUNNING] `rustc --crate-name foo src[/]main.rs [..]
+",
+            ),
+    );
+}