From 54e190af5c1ac7ebc0069d30e4181cde80f586d5 Mon Sep 17 00:00:00 2001
From: checkraisefold <checkraisefold@crf.gay>
Date: Wed, 30 Oct 2024 11:45:57 -0700
Subject: [PATCH] fflag gate

---
 Analysis/src/ConstraintGenerator.cpp | 23 ++++++++++++++++++-----
 tests/TypeInfer.definitions.test.cpp |  3 +++
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/Analysis/src/ConstraintGenerator.cpp b/Analysis/src/ConstraintGenerator.cpp
index 140a084ce..5686e1deb 100644
--- a/Analysis/src/ConstraintGenerator.cpp
+++ b/Analysis/src/ConstraintGenerator.cpp
@@ -34,6 +34,7 @@ LUAU_DYNAMIC_FASTINT(LuauTypeSolverRelease)
 LUAU_FASTFLAG(LuauTypestateBuiltins2)
 
 LUAU_FASTFLAGVARIABLE(LuauNewSolverVisitErrorExprLvalues)
+LUAU_FASTFLAGVARIABLE(LuauNewSolverPrePopulateClasses)
 
 namespace Luau
 {
@@ -753,6 +754,9 @@ void ConstraintGenerator::checkAliases(const ScopePtr& scope, AstStatBlock* bloc
         }
         else if (auto classDeclaration = stat->as<AstStatDeclareClass>())
         {
+            if (!FFlag::LuauNewSolverPrePopulateClasses)
+                continue;
+
             if (scope->exportedTypeBindings.count(classDeclaration->name.value))
             {
                 auto it = classDefinitionLocations.find(classDeclaration->name.value);
@@ -1671,7 +1675,7 @@ ControlFlow ConstraintGenerator::visit(const ScopePtr& scope, AstStatDeclareClas
 {
     // If a class with the same name was already defined, we skip over
     auto bindingIt = scope->exportedTypeBindings.find(declaredClass->name.value);
-    if (bindingIt == scope->exportedTypeBindings.end())
+    if (FFlag::LuauNewSolverPrePopulateClasses && bindingIt == scope->exportedTypeBindings.end())
         return ControlFlow::None;
 
     std::optional<TypeId> superTy = std::make_optional(builtinTypes->classType);
@@ -1688,9 +1692,12 @@ ControlFlow ConstraintGenerator::visit(const ScopePtr& scope, AstStatDeclareClas
 
         // We don't have generic classes, so this assertion _should_ never be hit.
         LUAU_ASSERT(lookupType->typeParams.size() == 0 && lookupType->typePackParams.size() == 0);
-        superTy = follow(lookupType->type);
+        if (FFlag::LuauNewSolverPrePopulateClasses)
+            superTy = follow(lookupType->type);
+        else
+            superTy = lookupType->type;
 
-        if (!get<ClassType>(*superTy))
+        if (!get<ClassType>(follow(*superTy)))
         {
             reportError(
                 declaredClass->location,
@@ -1711,8 +1718,14 @@ ControlFlow ConstraintGenerator::visit(const ScopePtr& scope, AstStatDeclareClas
 
     ctv->metatable = metaTy;
 
-    TypeId classBindTy = bindingIt->second.type;
-    emplaceType<BoundType>(asMutable(classBindTy), classTy);
+
+    if (FFlag::LuauNewSolverPrePopulateClasses)
+    {
+        TypeId classBindTy = bindingIt->second.type;
+        emplaceType<BoundType>(asMutable(classBindTy), classTy);
+    }
+    else
+        scope->exportedTypeBindings[className] = TypeFun{{}, classTy};
 
     if (declaredClass->indexer)
     {
diff --git a/tests/TypeInfer.definitions.test.cpp b/tests/TypeInfer.definitions.test.cpp
index aa25de03a..2ab90ab51 100644
--- a/tests/TypeInfer.definitions.test.cpp
+++ b/tests/TypeInfer.definitions.test.cpp
@@ -9,6 +9,8 @@
 
 using namespace Luau;
 
+LUAU_FASTFLAG(LuauNewSolverPrePopulateClasses)
+
 TEST_SUITE_BEGIN("DefinitionTests");
 
 TEST_CASE_FIXTURE(Fixture, "definition_file_simple")
@@ -492,6 +494,7 @@ TEST_CASE_FIXTURE(Fixture, "class_definition_indexer")
 
 TEST_CASE_FIXTURE(Fixture, "class_definitions_reference_other_classes")
 {
+    ScopedFastFlag _{FFlag::LuauNewSolverPrePopulateClasses, true};
     loadDefinition(R"(
         declare class Channel
             Messages: { Message }