Disallow labels of the form ////foo.

RELNOTES: Labels of the form ////foo are disallowed.
PiperOrigin-RevId: 192329081

2 files changed, 7 insertions, 2 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/Label.java b/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
index f271ea6c8b..92969c4111 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
@@ -257,11 +257,14 @@ public final class Label
    */
   private static PackageIdentifier validatePackageName(String packageIdentifier, String name)
       throws LabelSyntaxException {
-    String error = null;
+    if (packageIdentifier.startsWith("/")) {
+      throw new LabelSyntaxException(
+          "package names may not start with '/' (do you have too many '/'?)");
+    }
     try {
       return PackageIdentifier.parse(packageIdentifier);
     } catch (LabelSyntaxException e) {
-      error = e.getMessage();
+      String error = e.getMessage();
       error = "invalid package name '" + packageIdentifier + "': " + error;
       // This check is just for a more helpful error message
       // i.e. valid target name, invalid package name, colon-free label form
diff --git a/src/test/java/com/google/devtools/build/lib/cmdline/LabelTest.java b/src/test/java/com/google/devtools/build/lib/cmdline/LabelTest.java
index 7e34cc64e8..c31c20b85d 100644
--- a/src/test/java/com/google/devtools/build/lib/cmdline/LabelTest.java
+++ b/src/test/java/com/google/devtools/build/lib/cmdline/LabelTest.java
@@ -348,6 +348,8 @@ public class LabelTest {
     assertSyntaxError("package names may not end with '/'",
                       "//foo/:bar");
     assertSyntaxError("package names may not start with '/'", "///p:foo");
+    assertSyntaxError(
+        "package names may not start with '/' (do you have too many '/'?)", "////p:foo");
     assertSyntaxError("package names may not contain '//' path separators",
                       "//a//b:foo");
   }