Add a -V <bool> flag to frame variable/expression that enables execution of type validators. The jury is still out on what the user experience of type validators should be, so for now gate it on a specific flag. The mode I am using is prefix variables that fail to validate with a bang, and then emitting the actual validation error on a separate line. Of course, given the total absence of validators, this should never actually happen to you

llvm-svn: 217303
diff --git a/lldb/source/DataFormatters/ValueObjectPrinter.cpp b/lldb/source/DataFormatters/ValueObjectPrinter.cpp
index 65e5e3f..3ce5051 100644
--- a/lldb/source/DataFormatters/ValueObjectPrinter.cpp
+++ b/lldb/source/DataFormatters/ValueObjectPrinter.cpp
@@ -71,6 +71,8 @@
     
     if (ShouldPrintValueObject())
     {
+        PrintValidationMarkerIfNeeded();
+        
         PrintLocationIfNeeded();
         m_stream->Indent();
         
@@ -89,6 +91,8 @@
     else
         m_stream->EOL();
     
+    PrintValidationErrorIfNeeded();
+    
     return true;
 }
 
@@ -624,3 +628,44 @@
     else
         m_stream->EOL();
 }
+
+bool
+ValueObjectPrinter::ShouldPrintValidation ()
+{
+    return options.m_run_validator;
+}
+
+bool
+ValueObjectPrinter::PrintValidationMarkerIfNeeded ()
+{
+    if (!ShouldPrintValidation())
+        return false;
+    
+    m_validation = m_valobj->GetValidationStatus();
+    
+    if (TypeValidatorResult::Failure == m_validation.first)
+    {
+        m_stream->Printf("! ");
+        return true;
+    }
+    
+    return false;
+}
+
+bool
+ValueObjectPrinter::PrintValidationErrorIfNeeded ()
+{
+    if (!ShouldPrintValidation())
+        return false;
+    
+    if (TypeValidatorResult::Success == m_validation.first)
+        return false;
+    
+    if (m_validation.second.empty())
+        m_validation.second.assign("unknown error");
+    
+    m_stream->Printf(" ! validation error: %s", m_validation.second.c_str());
+    m_stream->EOL();
+    
+    return true;
+}