[Macros] Make 'LoadedCompilerPlugin' a wrapper of PointerUnion

Author: rintaro

include/swift/AST/TypeCheckRequests.h

@@ -3999,41 +3999,20 @@ class ExpandSynthesizedMemberMacroRequest
   bool isCached() const { return true; }
 };
 
-/// Load a plugin module with the given name.
-///
-///
+/// Represent a loaded plugin either an in-process library or an executable.
 class LoadedCompilerPlugin {
-  enum class PluginKind : uint8_t {
-    None,
-    InProcess,
-    Executable,
-  };
-  PluginKind kind;
-  void *ptr;
-
-  LoadedCompilerPlugin(PluginKind kind, void *ptr) : kind(kind), ptr(ptr) {
-    assert(ptr != nullptr || kind == PluginKind::None);
-  }
+  llvm::PointerUnion<LoadedLibraryPlugin *, LoadedExecutablePlugin *> ptr;
 
 public:
-  LoadedCompilerPlugin(std::nullptr_t) : kind(PluginKind::None), ptr(nullptr) {}
-
-  static LoadedCompilerPlugin inProcess(LoadedLibraryPlugin *ptr) {
-    return {PluginKind::InProcess, ptr};
-  }
-  static LoadedCompilerPlugin executable(LoadedExecutablePlugin *ptr) {
-    return {PluginKind::Executable, ptr};
-  }
+  LoadedCompilerPlugin(std::nullptr_t) : ptr(nullptr) {}
+  LoadedCompilerPlugin(LoadedLibraryPlugin *ptr) : ptr(ptr){};
+  LoadedCompilerPlugin(LoadedExecutablePlugin *ptr) : ptr(ptr){};
 
-  LoadedLibraryPlugin *getAsInProcessPlugin() const {
-    return kind == PluginKind::InProcess
-               ? static_cast<LoadedLibraryPlugin *>(ptr)
-               : nullptr;
+  LoadedLibraryPlugin *getAsLibraryPlugin() const {
+    return ptr.dyn_cast<LoadedLibraryPlugin *>();
   }
   LoadedExecutablePlugin *getAsExecutablePlugin() const {
-    return kind == PluginKind::Executable
-               ? static_cast<LoadedExecutablePlugin *>(ptr)
-               : nullptr;
+    return ptr.dyn_cast<LoadedExecutablePlugin *>();
   }
 };
 

lib/Sema/TypeCheckMacros.cpp

@@ -366,13 +366,14 @@ CompilerPluginLoadRequest::evaluate(Evaluator &evaluator, ASTContext *ctx,
                                     Identifier moduleName) const {
   // Check dynamic link library plugins.
   // i.e. '-plugin-path', and '-load-plugin-library'.
-  if (auto found = loadLibraryPluginByName(*ctx, moduleName))
-    return LoadedCompilerPlugin::inProcess(found);
+  if (auto found = loadLibraryPluginByName(*ctx, moduleName)) {
+    return found;
+  }
 
   // Fall back to executable plugins.
   // i.e. '-external-plugin-path', and '-load-plugin-executable'.
   if (auto *found = loadExecutablePluginByName(*ctx, moduleName)) {
-    return LoadedCompilerPlugin::executable(found);
+    return found;
   }
 
   return nullptr;
@@ -429,7 +430,7 @@ ExternalMacroDefinitionRequest::evaluate(Evaluator &evaluator, ASTContext *ctx,
   LoadedCompilerPlugin loaded =
       evaluateOrDefault(evaluator, loadRequest, nullptr);
 
-  if (auto loadedLibrary = loaded.getAsInProcessPlugin()) {
+  if (auto loadedLibrary = loaded.getAsLibraryPlugin()) {
     if (auto inProcess = resolveInProcessMacro(
             *ctx, moduleName, typeName, loadedLibrary))
       return *inProcess;