Fix avoiding a rebuild when moving around a workspace

src/cargo/core/compiler/fingerprint.rs

@@ -96,9 +96,10 @@ pub fn prepare_target<'a, 'cfg>(
             if output.flavor == FileFlavor::DebugInfo {
                 continue;
             }
-            missing_outputs |= !output.path.exists();
-            if let Some(ref link_dst) = output.hardlink {
-                missing_outputs |= !link_dst.exists();
+            if !output.path.exists() {
+                info!("missing output path {:?}", output.path);
+                missing_outputs = true;
+                break
             }
         }
     }

tests/testsuite/freshness.rs

@@ -1243,3 +1243,41 @@ fn dont_rebuild_based_on_plugins() {
         execs().with_status(0).with_stderr("[FINISHED] [..]\n"),
     );
 }
+
+#[test]
+fn reuse_workspace_lib() {
+    let p = project("p")
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "foo"
+                version = "0.1.1"
+
+                [workspace]
+
+                [dependencies]
+                bar = { path = 'bar' }
+            "#,
+        )
+        .file("src/lib.rs", "")
+        .file(
+            "bar/Cargo.toml",
+            r#"
+                [package]
+                name = "bar"
+                version = "0.1.1"
+            "#,
+        )
+        .file("bar/src/lib.rs", "")
+        .build();
+
+    assert_that(p.cargo("build"), execs().with_status(0));
+    assert_that(
+        p.cargo("test -p bar -v --no-run"),
+        execs().with_status(0).with_stderr("\
+[COMPILING] bar v0.1.1 ([..])
+[RUNNING] `rustc[..] --test [..]`
+[FINISHED] [..]
+"));
+}