Throw a static error when lvalue of an augmented assignment is a list.

RELNOTES:
  When the lvalue of an augmented assignment is a list, we now throw an error
  before evaluating the code (e.g. `a, b += 2, 3`).
PiperOrigin-RevId: 165906611

1 files changed, 5 insertions, 0 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/syntax/ValidationTest.java b/src/test/java/com/google/devtools/build/lib/syntax/ValidationTest.java
index 014d3be53a..604c53fe4b 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/ValidationTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/ValidationTest.java
@@ -39,6 +39,11 @@ public class ValidationTest extends EvaluationTestCase {
   }
 
   @Test
+  public void testAugmentedAssignmentWithMultipleLValues() {
+    checkError("cannot perform augmented assignment on a list or tuple expression", "a, b += 2, 3");
+  }
+
+  @Test
   public void testReturnOutsideFunction() throws Exception {
     checkError("Return statements must be inside a function", "return 2\n");
   }