Update targets to reduce syntax tree recreations due to ParseOption changes (#78093)

Additionally, reduce false positives in telemetry reporting
inefficiencies in project system interactions wrt Preprocessor
directives.

Author: arunchndr

src/Compilers/Core/MSBuildTask/Microsoft.CSharp.Core.targets

@@ -199,5 +199,7 @@
     <CommandLineArgsForDesignTimeEvaluation>-langversion:$(LangVersion)</CommandLineArgsForDesignTimeEvaluation>
     <CommandLineArgsForDesignTimeEvaluation Condition="'$(ChecksumAlgorithm)' != ''">$(CommandLineArgsForDesignTimeEvaluation) -checksumalgorithm:$(ChecksumAlgorithm)</CommandLineArgsForDesignTimeEvaluation>
     <CommandLineArgsForDesignTimeEvaluation Condition="'$(DefineConstants)' != ''">$(CommandLineArgsForDesignTimeEvaluation) -define:$(DefineConstants)</CommandLineArgsForDesignTimeEvaluation>
+    <CommandLineArgsForDesignTimeEvaluation Condition="'$(Features)' != ''">$(CommandLineArgsForDesignTimeEvaluation) -features:$(Features)</CommandLineArgsForDesignTimeEvaluation>
+    <CommandLineArgsForDesignTimeEvaluation Condition="'$(DocumentationFile)' != ''">$(CommandLineArgsForDesignTimeEvaluation) -doc:"$(DocumentationFile)"</CommandLineArgsForDesignTimeEvaluation>
   </PropertyGroup>
 </Project>

src/Compilers/Core/MSBuildTask/Microsoft.VisualBasic.Core.targets

@@ -164,5 +164,7 @@
     <CommandLineArgsForDesignTimeEvaluation>-langversion:$(LangVersion)</CommandLineArgsForDesignTimeEvaluation>
     <CommandLineArgsForDesignTimeEvaluation Condition="'$(ChecksumAlgorithm)' != ''">$(CommandLineArgsForDesignTimeEvaluation) -checksumalgorithm:$(ChecksumAlgorithm)</CommandLineArgsForDesignTimeEvaluation>
     <CommandLineArgsForDesignTimeEvaluation Condition="'$(FinalDefineConstants)' != ''">$(CommandLineArgsForDesignTimeEvaluation) -define:$(FinalDefineConstants)</CommandLineArgsForDesignTimeEvaluation>
+    <CommandLineArgsForDesignTimeEvaluation Condition="'$(Features)' != ''">$(CommandLineArgsForDesignTimeEvaluation) -features:$(Features)</CommandLineArgsForDesignTimeEvaluation>
+    <CommandLineArgsForDesignTimeEvaluation Condition="'$(DocumentationFile)' != ''">$(CommandLineArgsForDesignTimeEvaluation) -doc:"$(DocumentationFile)"</CommandLineArgsForDesignTimeEvaluation>
   </PropertyGroup>
 </Project>

src/VisualStudio/Core/Impl/ProjectSystem/CPS/CPSProjectFactory.cs

@@ -84,6 +84,7 @@ public async Task<IWorkspaceProjectContext> CreateProjectContextAsync(Guid id, s
 
             // Property added in VS 17.4 compiler targets capturing values of LangVersion and DefineConstants.
             // ChecksumAlgorithm value added to the property in 17.5.
+            // Features and DocumentationFile added after 17.14.
             //
             // Impact on Hot Reload: incorrect ChecksumAlgorithm will prevent Hot Reload in detecting changes correctly in certain scenarios.
             // However, given that projects that explicitly set ChecksumAlgorithm to a non-default value are rare and the project system

src/Workspaces/Core/Portable/Workspace/ProjectSystem/ProjectSystemProject.cs

@@ -31,7 +31,6 @@ namespace Microsoft.CodeAnalysis.Workspaces.ProjectSystem;
 
 internal sealed partial class ProjectSystemProject
 {
-    private static readonly char[] s_directorySeparator = [Path.DirectorySeparatorChar];
     private static readonly ImmutableArray<MetadataReferenceProperties> s_defaultMetadataReferenceProperties = [default(MetadataReferenceProperties)];
 
     private readonly ProjectSystemProjectFactory _projectSystemProjectFactory;
@@ -264,6 +263,9 @@ private void ChangeProjectProperty<T>(
 
             field = newValue;
 
+            _projectPropertyModificationsInBatch.Add(
+                (solutionChanges, projectUpdateState) => updateSolution(solutionChanges, projectUpdateState, oldValue));
+
             if (logThrowAwayTelemetry)
             {
                 var telemetryService = _projectSystemProjectFactory.SolutionServices.GetService<IWorkspaceTelemetryService>();
@@ -284,13 +286,29 @@ private void ChangeProjectProperty<T>(
 
                     if (!isFullyLoaded)
                     {
-                        TryReportCompilationThrownAway(_projectSystemProjectFactory.Workspace.CurrentSolution, Id);
+                        if (ShouldReportCompilationWillBeThrownAway(newValue, oldValue))
+                            TryReportCompilationThrownAway(_projectSystemProjectFactory.Workspace.CurrentSolution, Id);
                     }
                 }
             }
+        }
 
-            _projectPropertyModificationsInBatch.Add(
-                (solutionChanges, projectUpdateState) => updateSolution(solutionChanges, projectUpdateState, oldValue));
+        bool ShouldReportCompilationWillBeThrownAway(T newValue, T? oldValue)
+        {
+            // This method can be called for both AssemblyName (type string) and ParseOptions (type ParseOptions) changes.
+
+            // We report telemetry for AssemblyName changes.
+            if (newValue is not ParseOptions newParseOption)
+                return true;
+
+            // We don't want to report telemetry for the initial evaluation result.
+            if (oldValue is not ParseOptions oldParseOptions)
+                return false;
+
+            // ParseOptions should be reported if they differ by more than just preprocessor directives. (See DocumentState.UpdateParseOptionsAndSourceCodeKind)
+            var syntaxTreeFactoryService = _projectSystemProjectFactory.SolutionServices.GetRequiredLanguageService<ISyntaxTreeFactoryService>(Language);
+
+            return !syntaxTreeFactoryService.OptionsDifferOnlyByPreprocessorDirectives(oldParseOptions, newParseOption);
         }
     }
 
@@ -361,7 +379,7 @@ public string AssemblyName
     public CompilationOptions? CompilationOptions
     {
         get => _compilationOptions;
-        set => ChangeProjectProperty(ref _compilationOptions, value, s => s.WithProjectCompilationOptions(Id, value), logThrowAwayTelemetry: true);
+        set => ChangeProjectProperty(ref _compilationOptions, value, s => s.WithProjectCompilationOptions(Id, value));
     }
 
     // The property could be null if this is a non-C#/VB language and we don't have one for it. But we disallow assigning null, because C#/VB cannot end up null