Avoid json.h include in message.h

message.h is frequently used, and not all users need to know about the jsont
type hierarchy. Move the only function that requires knowing that a json_objectt
is-a jsont to the cpp file.

Author: tautschnig

src/util/message.cpp

@@ -9,6 +9,7 @@ Author: Daniel Kroening, [email protected]
 
 #include "message.h"
 
+#include "json.h"
 #include "string2int.h"
 
 void message_handlert::print(
@@ -140,3 +141,14 @@ void messaget::conditional_output(
     output_generator(mstream);
   }
 }
+
+messaget::mstreamt &messaget::mstreamt::operator<<(const json_objectt &data)
+{
+  if(this->tellp() > 0)
+    *this << eom; // force end of previous message
+  if(message.message_handler)
+  {
+    message.message_handler->print(message_level, data);
+  }
+  return *this;
+}

src/util/message.h

@@ -17,9 +17,10 @@ Author: Daniel Kroening, [email protected]
 
 #include "deprecate.h"
 #include "invariant.h"
-#include "json.h"
 #include "source_location.h"
 
+class json_objectt;
+class jsont;
 class xmlt;
 
 class message_handlert
@@ -248,16 +249,7 @@ class messaget
       return *this;
     }
 
-    mstreamt &operator << (const json_objectt &data)
-    {
-      if(this->tellp() > 0)
-        *this << eom; // force end of previous message
-      if(message.message_handler)
-      {
-        message.message_handler->print(message_level, data);
-      }
-      return *this;
-    }
+    mstreamt &operator<<(const json_objectt &data);
 
     template <class T>
     mstreamt &operator << (const T &x)