Simplify PublicTopLevelProgramGenerator (dotnet#60222)

* Simplify PublicTopLevelProgramGenerator

* Fix

* Use expression body

* Fix build

* Fix build error

* Fix accessibility check

* Pattern matching

* Fix typo

* Fix typo

* Fix build errors

Author: Youssef1313

src/Framework/AspNetCoreAnalyzers/src/SourceGenerators/PublicTopLevelProgramGenerator.cs

@@ -17,25 +17,27 @@ public partial class Program { }
 
     public void Initialize(IncrementalGeneratorInitializationContext context)
     {
-        var internalGeneratedProgramClass = context.CompilationProvider
+        var internalGeneratedProgramClass = context.CompilationProvider.Select(static (compilation, cancellationToken) =>
             // Get the entry point associated with the compilation, this maps to the Main method definition
-            .Select(static (compilation, cancellationToken) => compilation.GetEntryPoint(cancellationToken))
             // Get the containing symbol of the entry point, this maps to the Program class
-            .Select(static (symbol, _) => symbol?.ContainingSymbol)
-            // If the program class is already public, we don't need to generate anything.
-            .Select(static (symbol, _) => symbol?.DeclaredAccessibility == Accessibility.Public ? null : symbol)
-            // If the discovered `Program` type is not a class then its not
-            // generated and has been defined in source, so we can skip it
-            .Select(static (symbol, _) => symbol is INamedTypeSymbol { TypeKind: TypeKind.Class } ? symbol : null)
-            // If there are multiple partial declarations, then do nothing since we don't want
-            // to trample on visibility explicitly set by the user
-            .Select(static (symbol, _) => symbol is { DeclaringSyntaxReferences: { Length: 1 } declaringSyntaxReferences } ? declaringSyntaxReferences.Single() : null)
+            compilation.GetEntryPoint(cancellationToken)?.ContainingSymbol is INamedTypeSymbol
+                {
+                    // If the discovered `Program` type is not a class then its not
+                    // generated and has been defined in source, so we can skip it
+                    // If the program class is already public, we don't need to generate anything.
+                    DeclaredAccessibility: not Accessibility.Public,
+                    TypeKind: TypeKind.Class,
+                    // If there are multiple partial declarations, then do nothing since we don't want
+                    // to trample on visibility explicitly set by the user
+                    DeclaringSyntaxReferences: { Length: 1 } declaringSyntaxReferences
+                } &&
             // If the `Program` class is already declared in user code, we don't need to generate anything.
-            .Select(static (declaringSyntaxReference, cancellationToken) => declaringSyntaxReference?.GetSyntax(cancellationToken) is ClassDeclarationSyntax ? null : declaringSyntaxReference);
+            declaringSyntaxReferences.Single().GetSyntax(cancellationToken) is not ClassDeclarationSyntax
+        );
 
         context.RegisterSourceOutput(internalGeneratedProgramClass, (context, result) =>
         {
-            if (result is not null)
+            if (result)
             {
                 context.AddSource("PublicTopLevelProgram.Generated.g.cs", PublicPartialProgramClassSource);
             }