Print dependency diagnostics

- Downgrade lock file validation changes to warning instead of an error
- Don't show dependency information. Once we get log levels it'll be verbose.
The response file can be used to debug things.

src/Microsoft.DotNet.Tools.Compiler/Program.cs

@@ -73,6 +73,21 @@ namespace Microsoft.DotNet.Tools.Compiler
             // Create the library exporter
             var exporter = context.CreateExporter(configuration);
 
+            bool success = true;
+
+            // Print out dependency diagnostics
+            foreach (var diag in context.LibraryManager.GetAllDiagnostics())
+            {
+                success &= diag.Severity != DiagnosticMessageSeverity.Error;
+                Console.WriteLine(diag.FormattedMessage);
+            }
+
+            // If there were dependency errors don't bother compiling
+            if (!success)
+            {
+                return false;
+            }
+
             // Gather exports for the project
             var dependencies = exporter.GetCompilationDependencies().ToList();
 
@@ -96,7 +111,9 @@ namespace Microsoft.DotNet.Tools.Compiler
             }
 
             // Dump dependency data
-            ShowDependencyInfo(dependencies);
+            // TODO: Turn on only if verbose, we can look at the response
+            // file anyways
+            // ShowDependencyInfo(dependencies);
 
             // Hackily generate the output path
             if (string.IsNullOrEmpty(outputPath))

src/Microsoft.Extensions.ProjectModel/ProjectContextBuilder.cs

@@ -121,7 +121,7 @@ namespace Microsoft.Extensions.ProjectModel
                     ErrorCodes.NU1006,
                     $"{lockFileValidationMessage}. Please run \"dnu restore\" to generate a new lock file.",
                     Path.Combine(Project.ProjectDirectory, LockFile.FileName),
-                    DiagnosticMessageSeverity.Error));
+                    DiagnosticMessageSeverity.Warning));
             }
         }