1 files changed, 16 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/BinaryOperatorExpression.java b/src/main/java/com/google/devtools/build/lib/syntax/BinaryOperatorExpression.java
index de3bf92c2b..ba868188dd 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/BinaryOperatorExpression.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/BinaryOperatorExpression.java
@@ -19,6 +19,7 @@ import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.syntax.Concatable.Concatter;
 import com.google.devtools.build.lib.syntax.SkylarkList.MutableList;
 import com.google.devtools.build.lib.syntax.SkylarkList.Tuple;
+import java.io.IOException;
 import java.util.Collections;
 import java.util.IllegalFormatException;
 
@@ -55,7 +56,22 @@ public final class BinaryOperatorExpression extends Expression {
   }
 
   @Override
+  public void prettyPrint(Appendable buffer) throws IOException {
+    // TODO(bazel-team): Possibly omit parentheses when they are not needed according to operator
+    // precedence rules. This requires passing down more contextual information.
+    buffer.append('(');
+    lhs.prettyPrint(buffer);
+    buffer.append(' ');
+    buffer.append(operator.toString());
+    buffer.append(' ');
+    rhs.prettyPrint(buffer);
+    buffer.append(')');
+  }
+
+  @Override
   public String toString() {
+    // This omits the parentheses for brevity, but is not correct in general due to operator
+    // precedence rules.
     return lhs + " " + operator + " " + rhs;
   }