1 files changed, 47 insertions, 13 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/syntax/FunctionSignature.java b/src/main/java/com/google/devtools/build/lib/syntax/FunctionSignature.java
index e1eda63b6a..b38556d34e 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/FunctionSignature.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/FunctionSignature.java
@@ -343,10 +343,24 @@ public abstract class FunctionSignature implements Serializable {
           FunctionSignature.<T>valueListOrNull(types));
     }
 
+    public StringBuilder toStringBuilder(final StringBuilder sb) {
+      return toStringBuilder(sb, true, true, true, false);
+    }
+
     /**
-     * Append a representation of this signature to a string buffer.
+     * Appends a representation of this signature to a string buffer.
+     * @param sb Output StringBuffer
+     * @param showNames Determines whether the names of arguments should be printed
+     * @param showDefaults Determines whether the default values of arguments should be printed (if
+     * present)
+     * @param skipMissingTypeNames Determines whether missing type names should be omitted (true) or
+     * replaced with "object" (false). If showNames is false, "object" is always used as a type name
+     * to prevent blank spaces.
+     * @param skipFirstMandatory Determines whether the first mandatory parameter should be omitted.
      */
-    public StringBuilder toStringBuilder(final StringBuilder sb) {
+    public StringBuilder toStringBuilder(final StringBuilder sb, final boolean showNames,
+        final boolean showDefaults, final boolean skipMissingTypeNames,
+        final boolean skipFirstMandatory) {
       FunctionSignature signature = getSignature();
       Shape shape = signature.getShape();
       final ImmutableList<String> names = signature.getNames();
@@ -377,28 +391,46 @@ public abstract class FunctionSignature implements Serializable {
           isMore = true;
         }
         public void type(int i) {
-          if (types != null && types.get(i) != null) {
-            sb.append(": ").append(types.get(i).toString());
+          // We have to assign an artificial type string when the type is null.
+          // This happens when either
+          // a) there is no type defined (such as in user-defined functions) or
+          // b) the type is java.lang.Object.
+          boolean noTypeDefined = (types == null || types.get(i) == null);
+          String typeString = noTypeDefined ? "object" : types.get(i).toString();
+          if (noTypeDefined && showNames && skipMissingTypeNames) {
+            // This is the only case where we don't want to append typeString.
+            // If showNames = false, we ignore skipMissingTypeNames = true and append "object"
+            // in order to prevent blank spaces.
+          } else {
+            // We only append colons when there is a name.
+            if (showNames) {
+              sb.append(": ");
+            }
+            sb.append(typeString);
           }
         }
         public void mandatory(int i) {
           comma();
-          sb.append(names.get(i));
+          if (showNames) {
+            sb.append(names.get(i));
+          }
           type(i);
         }
         public void optional(int i) {
           mandatory(i);
-          sb.append(" = ");
-          if (defaultValues == null) {
-            sb.append("?");
-          } else {
-            Printer.write(sb, defaultValues.get(j++));
+          if (showDefaults) {
+            sb.append(" = ");
+            if (defaultValues == null) {
+              sb.append("?");
+            } else {
+              Printer.write(sb, defaultValues.get(j++));
+            }
           }
         }
       };
       Show show = new Show();
 
-      int i = 0;
+      int i = skipFirstMandatory ? 1 : 0;
       for (; i < mandatoryPositionals; i++) {
         show.mandatory(i);
       }
@@ -408,7 +440,7 @@ public abstract class FunctionSignature implements Serializable {
       if (hasStar) {
         show.comma();
         sb.append("*");
-        if (starArg) {
+        if (starArg && showNames) {
           sb.append(names.get(iStarArg));
         }
       }
@@ -421,7 +453,9 @@ public abstract class FunctionSignature implements Serializable {
       if (kwArg) {
         show.comma();
         sb.append("**");
-        sb.append(names.get(iKwArg));
+        if (showNames) {
+          sb.append(names.get(iKwArg));
+        }
       }
 
       return sb;