Don't build a solution when -preprocess or -targets is passed on the command line

src/MSBuild/Resources/Strings.resx

@@ -1349,6 +1349,9 @@
   <data name="NotWarnAsErrorWithoutWarnAsError" Visibility="Public">
     <value>MSBUILD : error MSB1062: The -warnnotaserror switch cannot be specified unless the -warnaserror switch is also specified and left empty.</value>
     <comment>{StrBegin="MSBUILD : error MSB1062: "}LOCALIZATION: The prefix "MSBUILD : error MSBxxxx:", "-warnnotaserror" and "-warnaserror" should not be localized.</comment>
+  </data>
+  <data name="UnsupportedSwitchForSolutionFiles" Visibility="Public">
+    <value>The '{0}' switch is not supported for solution files.</value>
   </data>
     <!--
         The command line message bucket is: MSB1001 - MSB1999

src/MSBuild/XMake.cs

@@ -758,10 +758,13 @@ public static ExitType Execute(
                     // Only display the message if /m isn't provided
                     if (cpuCount == 1 && FileUtilities.IsSolutionFilename(projectFile) && verbosity > LoggerVerbosity.Minimal
                         && switchesNotFromAutoResponseFile[CommandLineSwitches.ParameterizedSwitch.MaxCPUCount].Length == 0
-                        && switchesFromAutoResponseFile[CommandLineSwitches.ParameterizedSwitch.MaxCPUCount].Length == 0)
+                        && switchesFromAutoResponseFile[CommandLineSwitches.ParameterizedSwitch.MaxCPUCount].Length == 0
+                        && preprocessWriter != null
+                        && targetsWriter != null)
                     {
                         Console.WriteLine(ResourceUtilities.GetResourceString("PossiblyOmittedMaxCPUSwitch"));
                     }
+
                     if (preprocessWriter != null && !BuildEnvironmentHelper.Instance.RunningTests)
                     {
                         // Indicate to the engine that it can NOT toss extraneous file content: we want to
@@ -1207,8 +1210,8 @@ internal static bool BuildProject(
 
                 ToolsetDefinitionLocations toolsetDefinitionLocations = ToolsetDefinitionLocations.Default;
 
-                bool preprocessOnly = preprocessWriter != null && !FileUtilities.IsSolutionFilename(projectFile);
-                bool targetsOnly = targetsWriter != null && !FileUtilities.IsSolutionFilename(projectFile);
+                bool isPreprocess = preprocessWriter != null;
+                bool isTargets = targetsWriter != null;
 
                 projectCollection = new ProjectCollection(
                     globalProperties,
@@ -1217,7 +1220,7 @@ internal static bool BuildProject(
                     toolsetDefinitionLocations,
                     cpuCount,
                     onlyLogCriticalEvents,
-                    loadProjectsReadOnly: !preprocessOnly,
+                    loadProjectsReadOnly: !isPreprocess,
                     useAsynchronousLogging: true,
                     reuseProjectRootElementCache: s_isServerNode);
 
@@ -1226,9 +1229,11 @@ internal static bool BuildProject(
                     ThrowInvalidToolsVersionInitializationException(projectCollection.Toolsets, toolsVersion);
                 }
 
+                bool isSolution = FileUtilities.IsSolutionFilename(projectFile);
+
 #if FEATURE_XML_SCHEMA_VALIDATION
                 // If the user has requested that the schema be validated, do that here.
-                if (needToValidateProject && !FileUtilities.IsSolutionFilename(projectFile))
+                if (needToValidateProject && !isSolution)
                 {
                     Microsoft.Build.Evaluation.Project project = projectCollection.LoadProject(projectFile, globalProperties, toolsVersion);
                     Microsoft.Build.Evaluation.Toolset toolset = projectCollection.GetToolset(toolsVersion ?? project.ToolsVersion);
@@ -1246,22 +1251,41 @@ internal static bool BuildProject(
                 }
 #endif
 
-                if (preprocessOnly)
+                if (isPreprocess)
                 {
-                    Project project = projectCollection.LoadProject(projectFile, globalProperties, toolsVersion);
+                    // TODO: Support /preprocess for solution files. https://github.com/dotnet/msbuild/issues/7697
+                    if (isSolution)
+                    {
+                        Console.WriteLine(ResourceUtilities.GetResourceString("UnsupportedSwitchForSolutionFiles"), CommandLineSwitches.ParameterizedSwitch.Preprocess);
+                        success = false;
+                    }
+                    else
+                    {
+                        Project project = projectCollection.LoadProject(projectFile, globalProperties, toolsVersion);
 
-                    project.SaveLogicalProject(preprocessWriter);
+                        project.SaveLogicalProject(preprocessWriter);
 
-                    projectCollection.UnloadProject(project);
-                    success = true;
+                        projectCollection.UnloadProject(project);
+
+                        success = true;
+                    }
                 }
 
-                if (targetsOnly)
+                if (isTargets)
                 {
-                    success = PrintTargets(projectFile, toolsVersion, globalProperties, targetsWriter, projectCollection);
+                    // TODO: Support /targets for solution files. https://github.com/dotnet/msbuild/issues/7697
+                    if (isSolution)
+                    {
+                        Console.WriteLine(ResourceUtilities.GetResourceString("UnsupportedSwitchForSolutionFiles"), CommandLineSwitches.ParameterizedSwitch.Targets);
+                        success = false;
+                    }
+                    else
+                    {
+                        success = PrintTargets(projectFile, toolsVersion, globalProperties, targetsWriter, projectCollection);
+                    }
                 }
 
-                if (!preprocessOnly && !targetsOnly)
+                if (!isPreprocess && !isTargets)
                 {
                     BuildParameters parameters = new BuildParameters(projectCollection);