Negative clearance means test will be ignored, not rule.

pcbnew/drc/drc_engine.cpp

@@ -881,14 +881,6 @@ DRC_CONSTRAINT DRC_ENGINE::EvalRules( DRC_CONSTRAINT_T aConstraintType, const BO
                     REPORT( wxString::Format( _( "Checking %s clearance: %s." ),
                                               EscapeHTML( c->constraint.GetName() ),
                                               MessageTextFromValue( c->constraint.m_Value.Min() ) ) )
-
-                    if( c->constraint.GetValue().Min() < 0 )
-                    {
-                        REPORT( implicit ? _( "Negative clearance specified; constraint ignored." )
-                                         : _( "Negative clearance specified; rule ignored." ) )
-                        return true;
-                    }
-
                     break;
 
                 case DIFF_PAIR_MAX_UNCOUPLED_CONSTRAINT:

pcbnew/tools/board_inspection_tool.cpp

@@ -772,8 +772,17 @@ int BOARD_INSPECTION_TOOL::InspectClearance( const TOOL_EVENT& aEvent )
                 reportCompileError( r );
 
             r->Report( "" );
-            r->Report( wxString::Format( _( "Resolved clearance: %s." ),
-                                         m_frame->StringFromValue( clearance, true ) ) );
+
+            if( clearance < 0 )
+            {
+                r->Report( wxString::Format( _( "Resolved clearance: %s; clearance will not be tested." ),
+                                             m_frame->StringFromValue( clearance, true ) ) );
+            }
+            else
+            {
+                r->Report( wxString::Format( _( "Resolved clearance: %s." ),
+                                             m_frame->StringFromValue( clearance, true ) ) );
+            }
         }
 
         r->Flush();