Emit Warning When Using CLI Switches from Auto-Response File Lead to Errors

src/MSBuild.UnitTests/XMake_Tests.cs

@@ -1571,6 +1571,48 @@ public void ResponseFileInProjectDirectoryWithSolutionProjectDifferentNamesShoul
             successfulExit.ShouldBeTrue();
         }
 
+        [Fact]
+        public void ResponseFileNoticeIsPrintedOnSwitchError()
+        {
+            _env.SetEnvironmentVariable("DOTNET_CLI_UI_LANGUAGE", "en-US");
+            var directory = _env.CreateFolder();
+            var content = ObjectModelHelpers.CleanupFileContents("<Project><Target Name='t'><Message Text='Completed'/></Target></Project>");
+            directory.CreateFile("foo.proj", content);
+            var projectPath = directory.CreateFile("bar.proj", content).Path;
+            var rspPath = directory.CreateFile("Directory.Build.rsp", "foo.proj").Path;
+
+            string output = RunnerUtilities.ExecMSBuild($"\"{projectPath}\"", out var successfulExit, _output);
+
+            successfulExit.ShouldBeFalse();
+            int noticeIndex = output.IndexOf("Some command line switches were read from", StringComparison.OrdinalIgnoreCase);
+            int errorIndex = output.IndexOf("MSB1008", StringComparison.OrdinalIgnoreCase);
+            noticeIndex.ShouldBeGreaterThanOrEqualTo(0);
+            errorIndex.ShouldBeGreaterThanOrEqualTo(0);
+            noticeIndex.ShouldBeLessThan(errorIndex);
+            output.ShouldContain(rspPath);
+        }
+
+        [Fact]
+        public void ExplicitResponseFileNoticeIsPrintedOnSwitchError()
+        {
+            _env.SetEnvironmentVariable("DOTNET_CLI_UI_LANGUAGE", "en-US");
+            var directory = _env.CreateFolder();
+            var content = ObjectModelHelpers.CleanupFileContents("<Project><Target Name='t'><Message Text='Completed'/></Target></Project>");
+            directory.CreateFile("foo.proj", content);
+            var projectPath = directory.CreateFile("bar.proj", content).Path;
+            var rspPath = directory.CreateFile("explicit.rsp", "foo.proj").Path;
+
+            string output = RunnerUtilities.ExecMSBuild($"\"{projectPath}\" @\"{rspPath}\" -noAutoResponse", out var successfulExit, _output);
+
+            successfulExit.ShouldBeFalse();
+            int noticeIndex = output.IndexOf("Some command line switches were read from", StringComparison.OrdinalIgnoreCase);
+            int errorIndex = output.IndexOf("MSB1008", StringComparison.OrdinalIgnoreCase);
+            noticeIndex.ShouldBeGreaterThanOrEqualTo(0);
+            errorIndex.ShouldBeGreaterThanOrEqualTo(0);
+            noticeIndex.ShouldBeLessThan(errorIndex);
+            output.ShouldContain(rspPath);
+        }
+
         /// <summary>
         /// Any msbuild.rsp in the directory of the specified project/solution should be read, and should
         /// take priority over any other response files. Sanity test when there isn't one.

src/MSBuild/Resources/Strings.resx

@@ -1321,6 +1321,20 @@
       where the switches are coming from.
     </comment>
   </data>
+  <data name="PickedUpSwitchesFromResponseFile" xml:space="preserve">
+    <value>Some command line switches were read from this response file:</value>
+    <comment>
+      UE: This message appears before a command-line parsing error when switches were read from a response file: otherwise the user may be unaware where the switches are coming from.
+      LOCALIZATION: The response file path is printed on a separate line after this message.
+    </comment>
+  </data>
+  <data name="PickedUpSwitchesFromResponseFiles" xml:space="preserve">
+    <value>Some command line switches were read from these response files:</value>
+    <comment>
+      UE: This message appears before a command-line parsing error when switches were read from response files: otherwise the user may be unaware where the switches are coming from.
+      LOCALIZATION: The response file paths are printed on separate lines after this message.
+    </comment>
+  </data>
   <data name="ProjectNotFoundError" xml:space="preserve">
     <value>MSBUILD : error MSB1009: Project file does not exist.</value>
     <comment>{StrBegin="MSBUILD : error MSB1009: "}UE: This message does not need in-line parameters because the exception takes care of displaying the invalid arg.