Add support for MSBUILD_LOGGING_ARGS

src/Build/BackEnd/BuildManager/BuildManager.cs

@@ -396,6 +396,16 @@ public static BuildManager DefaultBuildManager
         /// </summary>
         LegacyThreadingData IBuildComponentHost.LegacyThreadingData => _legacyThreadingData;
 
+        /// <summary>
+        /// Enumeration describing the severity of a deferred build message.
+        /// </summary>
+        public enum DeferredBuildMessageSeverity
+        {
+            Message = 1,
+            Warning,
+            Error
+        }
+
         /// <summary>
         /// <see cref="BuildManager.BeginBuild(BuildParameters,IEnumerable{DeferredBuildMessage})"/>
         /// </summary>
@@ -407,18 +417,42 @@ public readonly struct DeferredBuildMessage
 
             public string? FilePath { get; }
 
+            public DeferredBuildMessageSeverity MessageSeverity { get; } = DeferredBuildMessageSeverity.Message;
+
+            /// <summary>
+            /// Build event code (e.g., "MSB1070").
+            /// </summary>
+            public string? Code { get; }
+
             public DeferredBuildMessage(string text, MessageImportance importance)
             {
                 Importance = importance;
                 Text = text;
                 FilePath = null;
+                Code = null;
             }
 
             public DeferredBuildMessage(string text, MessageImportance importance, string filePath)
             {
                 Importance = importance;
                 Text = text;
                 FilePath = filePath;
+                Code = null;
+            }
+
+            /// <summary>
+            /// Creates a deferred warning message.
+            /// </summary>
+            /// <param name="text">The warning message text.</param>
+            /// <param name="code">The build message code (e.g., "MSB1070").</param>
+            /// <param name="messageSeverity">The severity of the deferred build message.</param>
+            public DeferredBuildMessage(string text, string code, DeferredBuildMessageSeverity messageSeverity)
+            {
+                Importance = MessageImportance.Normal;
+                Text = text;
+                FilePath = null;
+                Code = code;
+                MessageSeverity = messageSeverity;
             }
         }
 
@@ -3154,7 +3188,20 @@ private static void LogDeferredMessages(ILoggingService loggingService, IEnumera
 
             foreach (var message in deferredBuildMessages)
             {
-                loggingService.LogCommentFromText(BuildEventContext.Invalid, message.Importance, message.Text);
+                if (message.MessageSeverity is DeferredBuildMessageSeverity.Warning)
+                {
+                    loggingService.LogWarningFromText(
+                        BuildEventContext.Invalid,
+                        subcategoryResourceName: null,
+                        warningCode: message.Code,
+                        helpKeyword: null,
+                        file: BuildEventFileInfo.Empty,
+                        message: message.Text);
+                }
+                else
+                {
+                    loggingService.LogCommentFromText(BuildEventContext.Invalid, message.Importance, message.Text);
+                }
 
                 // If message includes a file path, include that file
                 if (message.FilePath is not null)

src/Framework/Traits.cs

@@ -135,6 +135,28 @@ public Traits()
         /// </summary>
         public const string UseMSBuildServerEnvVarName = "MSBUILDUSESERVER";
 
+        /// <summary>
+        /// Name of environment variable for logging arguments (e.g., -bl, -check).
+        /// </summary>
+        public const string MSBuildLoggingArgsEnvVarName = "MSBUILD_LOGGING_ARGS";
+
+        /// <summary>
+        /// Name of environment variable that controls the logging level for diagnostic messages
+        /// emitted when processing the MSBUILD_LOGGING_ARGS environment variable.
+        /// Set to "message" to emit as low-importance build messages instead of console warnings.
+        /// </summary>
+        public const string MSBuildLoggingArgsLevelEnvVarName = "MSBUILD_LOGGING_ARGS_LEVEL";
+
+        /// <summary>
+        /// Value of the MSBUILD_LOGGING_ARGS environment variable.
+        /// </summary>
+        public static string? MSBuildLoggingArgs => Environment.GetEnvironmentVariable(MSBuildLoggingArgsEnvVarName);
+
+        /// <summary>
+        /// Gets if the logging level for MSBUILD_LOGGING_ARGS diagnostic is message.
+        /// </summary>
+        public readonly bool EmitLogsAsMessage = string.Equals(Environment.GetEnvironmentVariable(MSBuildLoggingArgsLevelEnvVarName), "message", StringComparison.OrdinalIgnoreCase);
+
         public readonly bool DebugEngine = !string.IsNullOrEmpty(Environment.GetEnvironmentVariable("MSBuildDebugEngine"));
         public readonly bool DebugScheduler;
         public readonly bool DebugNodeCommunication;