commit b5ae7d35c3489f1894cca3bba51073cb0edae7d1
author vladmos <vladmos@google.com> Thu Jun 27 07:01:11 2019 -0700
committer Copybara-Service <copybara-worker@google.com> Thu Jun 27 07:02:11 2019 -0700
tree 75e71d43bb291e9949725202a01084e137c60479
parent 9f7fe693ce6f0c6f8dd832959b8d4b08bc958dad

Throw a Starlark error in case of no outputs

With https://github.com/bazelbuild/bazel/commit/af53a11104b549cca8b593a1f8cac224a21727da, if a Starlark error is not thrown hereexplicitly,
Blaze crashes later in SpawnAction.java when it calls `output.get(0)`.

PiperOrigin-RevId: 255392440

src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkActionFactory.java

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkActionFactory.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkActionFactory.java
index b7197d0..6659cd9 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkActionFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkActionFactory.java
@@ -444,7 +444,13 @@
       builder.addTransitiveInputs(inputSet);
       inputArtifacts = inputSet;
     }
-    builder.addOutputs(outputs.getContents(Artifact.class, "outputs"));
+
+    @SuppressWarnings("unchecked")
+    List<Artifact> outputArtifacts = outputs.getContents(Artifact.class, "outputs");
+    if (outputArtifacts.isEmpty()) {
+      throw new EvalException(location, "param 'outputs' may not be empty");
+    }
+    builder.addOutputs(outputArtifacts);
 
     if (unusedInputsList != Runtime.NONE) {
       if (!starlarkSemantics.experimentalStarlarkUnusedInputsList()) {

src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java

diff --git a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java
index 45d1b90..5f39a92 100644
--- a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java
@@ -3061,4 +3061,21 @@
 
     getConfiguredTarget("//test:r");
   }
+
+  @Test
+  public void testNoOutputsError() throws Exception {
+    scratch.file(
+        "test/skylark/test_rule.bzl",
+        "def _my_rule_impl(ctx):",
+        "  ctx.actions.run_shell(outputs=[], command='foo')",
+        "my_rule = rule(implementation = _my_rule_impl, executable = True)");
+    scratch.file(
+        "test/skylark/BUILD",
+        "load('//test/skylark:test_rule.bzl', 'my_rule')",
+        "my_rule(name = 'target')");
+
+    reporter.removeHandler(failFastHandler);
+    getConfiguredTarget("//test/skylark:target");
+    assertContainsEvent("param 'outputs' may not be empty");
+  }
 }