Fix `equals()` and `hashCode()` for artifacts: artifacts of different classes are not equal.

Also validate that there are no tree and file artifacts with the same exec path.

Fixes #4668.

Closes #5284.

Change-Id: Id97c0407a476a5bfc697b4ca7b858e3d0c0f8c75
PiperOrigin-RevId: 198540425

1 files changed, 4 insertions, 1 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/actions/Artifact.java b/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
index 95714cdc8a..f18e14f0d0 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
@@ -228,7 +228,7 @@ public class Artifact
       throw new IllegalArgumentException(
           "it is illegal to create an artifact with an empty execPath");
     }
-    this.hashCode = execPath.hashCode();
+    this.hashCode = execPath.hashCode() + this.getClass().hashCode() * 13;
     this.root = root;
     this.execPath = execPath;
     this.rootRelativePath = rootRelativePath;
@@ -641,6 +641,9 @@ public class Artifact
     if (!(other instanceof Artifact)) {
       return false;
     }
+    if (!getClass().equals(other.getClass())) {
+      return false;
+    }
     // We don't bother to check root in the equivalence relation, because we
     // assume that no root is an ancestor of another one.
     Artifact that = (Artifact) other;