Review

class FunctionTypeBuilder {
  /**
   * If we haven't found a return value yet, try to look at the "return"
   * statements in the function.
   */
  FunctionTypeBuilder inferReturnStatementsAsLastResort(
      @Nullable Node functionBlock) {
    if (functionBlock == null || compiler.getInput(sourceName).isExtern()) {
      return this;
    }
    Preconditions.checkArgument(functionBlock.getType() == Token.BLOCK);
    if (returnType == null) {
      boolean hasNonEmptyReturns = false;
      List<Node> worklist = Lists.newArrayList(functionBlock);
      while (!worklist.isEmpty()) {
        Node current = worklist.remove(worklist.size() - 1);
        int cType = current.getType();
        if (cType == Token.RETURN && current.getFirstChild() != null ||
            cType == Token.THROW) {
          hasNonEmptyReturns = true;
          break;
        } else if (NodeUtil.isStatementBlock(current) ||
            NodeUtil.isControlStructure(current)) {
          for (Node child = current.getFirstChild();
               child != null; child = child.getNext()) {
            worklist.add(child);
          }
        }
      }

      if (!hasNonEmptyReturns) {
        returnType = typeRegistry.getNativeType(VOID_TYPE);
        returnTypeInferred = true;
      }
    }
    return this;
  }

}