Route dotnet-ef diagnostic output to stderr, fix premature help exit code

src/dotnet-ef/Program.cs

@@ -9,6 +9,11 @@ internal static class Program
 {
     private static int Main(string[] args)
     {
+        // Redirect Console.Out to stderr so that help text and diagnostics
+        // don't pollute stdout. Actual data output uses the original stdout saved by Reporter.
+        Reporter.SetStdOut(Console.Out);
+        Console.SetOut(Console.Error);
+
         var app = new CommandLineApplication(throwOnUnexpectedArg: false) { Name = "dotnet ef" };
 
         new RootCommand().Configure(app);

src/dotnet-ef/RootCommand.cs

@@ -54,7 +54,7 @@ protected override int Execute(string[] _)
     {
         var commands = _args!.TakeWhile(a => a[0] != '-').ToList();
         if (_help!.HasValue()
-            || ShouldHelp(commands))
+            || ShouldHelp(commands, _args!))
         {
             return ShowHelp(_help.HasValue(), commands);
         }
@@ -333,9 +333,11 @@ private static string GetVersion()
         => typeof(RootCommand).Assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>()!
             .InformationalVersion;
 
-    private static bool ShouldHelp(IReadOnlyList<string> commands)
-        => commands.Count == 0
-            || (commands.Count == 1
+    private static bool ShouldHelp(IReadOnlyList<string> commands, IList<string> args)
+        => args.Count == 0
+            || commands.Count == 0
+            || (args.Count == 1
+                && commands.Count == 1
                 && (commands[0] == "database"
                     || commands[0] == "dbcontext"
                     || commands[0] == "migrations"));

src/ef/AnsiConsole.cs

@@ -6,6 +6,7 @@ namespace Microsoft.EntityFrameworkCore.Tools;
 internal static class AnsiConsole
 {
     public static readonly AnsiTextWriter Out = new(Console.Out);
+    public static readonly AnsiTextWriter Error = new(Console.Error);
 
     public static void WriteLine(string? text)
         => Out.WriteLine(text);

src/ef/Program.cs

@@ -16,6 +16,12 @@ private static int Main(string[] args)
             Console.OutputEncoding = Encoding.UTF8;
         }
 
+        // Redirect Console.Out to stderr so that any user-configured logging providers
+        // (e.g. ConsoleLogger) don't pollute stdout with diagnostic messages.
+        // Actual data output uses the original stdout saved by Reporter.
+        Reporter.SetStdOut(Console.Out);
+        Console.SetOut(Console.Error);
+
         var app = new CommandLineApplication { Name = "ef" };
 
         new RootCommand().Configure(app);

src/ef/Reporter.cs

@@ -14,22 +14,31 @@ internal static class Reporter
     public const string DataPrefix = "data:    ";
     public const string VerbosePrefix = "verbose: ";
 
+    private static TextWriter _stdOut = Console.Out;
+    private static AnsiTextWriter _stdOutAnsi = new(Console.Out);
+
     public static bool IsVerbose { get; set; }
     public static bool NoColor { get; set; }
     public static bool PrefixOutput { get; set; }
 
+    public static void SetStdOut(TextWriter writer)
+    {
+        _stdOut = writer;
+        _stdOutAnsi = new AnsiTextWriter(writer);
+    }
+
     [return: NotNullIfNotNull(nameof(value))]
     public static string? Colorize(string? value, Func<string?, string> colorizeFunc)
         => NoColor ? value : colorizeFunc(value);
 
     public static void WriteError(string? message)
-        => WriteLine(Prefix(ErrorPrefix, Colorize(message, x => Bold + Red + x + Reset)));
+        => WriteStdErr(Prefix(ErrorPrefix, Colorize(message, x => Bold + Red + x + Reset)));
 
     public static void WriteWarning(string? message)
-        => WriteLine(Prefix(WarningPrefix, Colorize(message, x => Bold + Yellow + x + Reset)));
+        => WriteStdErr(Prefix(WarningPrefix, Colorize(message, x => Bold + Yellow + x + Reset)));
 
     public static void WriteInformation(string? message)
-        => WriteLine(Prefix(InfoPrefix, message));
+        => WriteStdErr(Prefix(InfoPrefix, message));
 
     public static void WriteData(string? message)
         => WriteLine(Prefix(DataPrefix, Colorize(message, x => Bold + Gray + x + Reset)));
@@ -38,7 +47,7 @@ public static void WriteVerbose(string? message)
     {
         if (IsVerbose)
         {
-            WriteLine(Prefix(VerbosePrefix, Colorize(message, x => Bold + Black + x + Reset)));
+            WriteStdErr(Prefix(VerbosePrefix, Colorize(message, x => Bold + Black + x + Reset)));
         }
     }
 
@@ -55,11 +64,29 @@ private static void WriteLine(string? value)
     {
         if (NoColor)
         {
-            Console.WriteLine(value);
+            _stdOut.WriteLine(value);
+        }
+        else
+        {
+            _stdOutAnsi.WriteLine(value);
+        }
+    }
+
+    private static void WriteStdErr(string? value)
+    {
+        if (PrefixOutput)
+        {
+            WriteLine(value);
+            return;
+        }
+
+        if (NoColor)
+        {
+            Console.Error.WriteLine(value);
         }
         else
         {
-            AnsiConsole.WriteLine(value);
+            AnsiConsole.Error.WriteLine(value);
         }
     }
 }