2 files changed, 22 insertions, 0 deletions
diff --git a/src/tools/skylark/java/com/google/devtools/skylark/skylint/ControlFlowChecker.java b/src/tools/skylark/java/com/google/devtools/skylark/skylint/ControlFlowChecker.java
index e11c3d2a5f..821749ca3d 100644
--- a/src/tools/skylark/java/com/google/devtools/skylark/skylint/ControlFlowChecker.java
+++ b/src/tools/skylark/java/com/google/devtools/skylark/skylint/ControlFlowChecker.java
@@ -18,6 +18,7 @@ import com.google.common.base.Preconditions;
 import com.google.devtools.build.lib.syntax.BuildFileAST;
 import com.google.devtools.build.lib.syntax.Expression;
 import com.google.devtools.build.lib.syntax.ExpressionStatement;
+import com.google.devtools.build.lib.syntax.ForStatement;
 import com.google.devtools.build.lib.syntax.FuncallExpression;
 import com.google.devtools.build.lib.syntax.FunctionDefStatement;
 import com.google.devtools.build.lib.syntax.Identifier;
@@ -27,6 +28,7 @@ import com.google.devtools.build.lib.syntax.ReturnStatement;
 import com.google.devtools.build.lib.syntax.Statement;
 import com.google.devtools.build.lib.syntax.SyntaxTreeVisitor;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.stream.Stream;
@@ -83,6 +85,13 @@ public class ControlFlowChecker extends SyntaxTreeVisitor {
   }
 
   @Override
+  public void visit(ForStatement node) {
+    ControlFlowInfo noIteration = ControlFlowInfo.copy(cfi);
+    super.visit(node);
+    cfi = ControlFlowInfo.join(Arrays.asList(noIteration, cfi));
+  }
+
+  @Override
   public void visit(ReturnStatement node) {
     // Should be rejected by parser, but we may have been fed a bad AST.
     Preconditions.checkState(cfi != null, "AST has illegal top-level return statement");
diff --git a/src/tools/skylark/javatests/com/google/devtools/skylark/skylint/ControlFlowCheckerTest.java b/src/tools/skylark/javatests/com/google/devtools/skylark/skylint/ControlFlowCheckerTest.java
index 0b00745ff2..6266f6f9b9 100644
--- a/src/tools/skylark/javatests/com/google/devtools/skylark/skylint/ControlFlowCheckerTest.java
+++ b/src/tools/skylark/javatests/com/google/devtools/skylark/skylint/ControlFlowCheckerTest.java
@@ -127,6 +127,19 @@ public class ControlFlowCheckerTest {
   }
 
   @Test
+  public void testForAndFallOffEnd() throws Exception {
+    Truth.assertThat(
+            findIssues(
+                    "def some_function():",
+                    "  for x in []:",
+                    "    return x",
+                    "  print('foo')",
+                    "  # return missing here")
+                .toString())
+        .contains("some but not all execution paths of 'some_function' return a value");
+  }
+
+  @Test
   public void testAlwaysReturnButSometimesWithoutValue() throws Exception {
     String messages =
         findIssues(