[torque] Also predeclare generics

This allows generic specializations to appear
before the generic itself.

Bug: v8:7793
Change-Id: I127fb49380a14cdf2a63854117d25fc865a95352
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1599178Reviewed-by: Simon Zünd <szuend@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61290}

src/torque/declaration-visitor.cc

@@ -22,7 +22,7 @@ Namespace* GetOrCreateNamespace(const std::string& name) {
   return existing_namespaces.front();
 }
 
-void TypeDeclarationVisitor::Predeclare(Declaration* decl) {
+void PredeclarationVisitor::Predeclare(Declaration* decl) {
   CurrentSourcePosition::Scope scope(decl->pos);
   switch (decl->kind) {
 #define ENUM_ITEM(name)        \
@@ -32,8 +32,10 @@ void TypeDeclarationVisitor::Predeclare(Declaration* decl) {
 #undef ENUM_ITEM
     case AstNode::Kind::kNamespaceDeclaration:
       return Predeclare(NamespaceDeclaration::cast(decl));
+    case AstNode::Kind::kGenericDeclaration:
+      return Predeclare(GenericDeclaration::cast(decl));
     default:
-      // This visitor only processes type declaration nodes.
+      // Only processes type declaration nodes, namespaces and generics.
       break;
   }
 }
@@ -204,10 +206,6 @@ void DeclarationVisitor::Visit(StandardDeclaration* decl) {
   Visit(decl->callable, signature, decl->body);
 }
 
-void DeclarationVisitor::Visit(GenericDeclaration* decl) {
-  Declarations::DeclareGeneric(decl->callable->name, decl);
-}
-
 void DeclarationVisitor::Visit(SpecializationDeclaration* decl) {
   if ((decl->body != nullptr) == decl->external) {
     std::stringstream stream;
@@ -382,7 +380,7 @@ Callable* DeclarationVisitor::Specialize(
   return callable;
 }
 
-void TypeDeclarationVisitor::ResolvePredeclarations() {
+void PredeclarationVisitor::ResolvePredeclarations() {
   for (auto& p : GlobalContext::AllDeclarables()) {
     if (const TypeAlias* alias = TypeAlias::DynamicCast(p.get())) {
       CurrentScope::Scope scope_activator(alias->ParentScope());

src/torque/declaration-visitor.h

@@ -20,7 +20,7 @@ namespace torque {
 
 Namespace* GetOrCreateNamespace(const std::string& name);
 
-class TypeDeclarationVisitor {
+class PredeclarationVisitor {
  public:
   static void Predeclare(Ast* ast) {
     CurrentScope::Scope current_namespace(GlobalContext::GetDefaultNamespace());
@@ -37,6 +37,9 @@ class TypeDeclarationVisitor {
   static void Predeclare(TypeDeclaration* decl) {
     Declarations::PredeclareTypeAlias(decl->name, decl, false);
   }
+  static void Predeclare(GenericDeclaration* decl) {
+    Declarations::DeclareGeneric(decl->callable->name, decl);
+  }
 };
 
 class DeclarationVisitor {
@@ -85,7 +88,9 @@ class DeclarationVisitor {
 
   static void Visit(ConstDeclaration* decl);
   static void Visit(StandardDeclaration* decl);
-  static void Visit(GenericDeclaration* decl);
+  static void Visit(GenericDeclaration* decl) {
+    // The PredeclarationVisitor already handled this case.
+  }
   static void Visit(SpecializationDeclaration* decl);
   static void Visit(ExternConstDeclaration* decl);
   static void Visit(CppIncludeDeclaration* decl);

src/torque/torque-compiler.cc

@@ -55,8 +55,8 @@ void CompileCurrentAst(TorqueCompilerOptions options) {
 
   // Two-step process of predeclaration + resolution allows to resolve type
   // declarations independent of the order they are given.
-  TypeDeclarationVisitor::Predeclare(GlobalContext::Get().ast());
-  TypeDeclarationVisitor::ResolvePredeclarations();
+  PredeclarationVisitor::Predeclare(GlobalContext::Get().ast());
+  PredeclarationVisitor::ResolvePredeclarations();
 
   // Process other declarations.
   DeclarationVisitor::Visit(GlobalContext::Get().ast());