Merge branch 'upstream' into merge

Analysis/include/Luau/ConstraintGenerator.h

@@ -150,7 +150,7 @@ private:
      */
     ScopePtr childScope(AstNode* node, const ScopePtr& parent);
 
-    std::optional<TypeId> lookup(Scope* scope, DefId def);
+    std::optional<TypeId> lookup(Scope* scope, DefId def, bool prototype = true);
 
     /**
      * Adds a new constraint with no dependencies to a given scope.

Analysis/include/Luau/DataFlowGraph.h

@@ -74,8 +74,15 @@ private:
 
 struct DfgScope
 {
+    enum ScopeType
+    {
+        Linear,
+        Loop,
+        Function,
+    };
+
     DfgScope* parent;
-    bool isLoopScope;
+    ScopeType scopeType;
 
     using Bindings = DenseHashMap<Symbol, const Def*>;
     using Props = DenseHashMap<const Def*, std::unordered_map<std::string, const Def*>>;
@@ -117,7 +124,17 @@ private:
 
     std::vector<std::unique_ptr<DfgScope>> scopes;
 
-    DfgScope* childScope(DfgScope* scope, bool isLoopScope = false);
+    struct FunctionCapture
+    {
+        std::vector<DefId> captureDefs;
+        std::vector<DefId> allVersions;
+        size_t versionOffset = 0;
+    };
+
+    DenseHashMap<Symbol, FunctionCapture> captures{Symbol{}};
+    void resolveCaptures();
+
+    DfgScope* childScope(DfgScope* scope, DfgScope::ScopeType scopeType = DfgScope::Linear);
 
     void join(DfgScope* p, DfgScope* a, DfgScope* b);
     void joinBindings(DfgScope::Bindings& p, const DfgScope::Bindings& a, const DfgScope::Bindings& b);
@@ -167,11 +184,11 @@ private:
     DataFlowResult visitExpr(DfgScope* scope, AstExprError* error);
 
     void visitLValue(DfgScope* scope, AstExpr* e, DefId incomingDef, bool isCompoundAssignment = false);
-    void visitLValue(DfgScope* scope, AstExprLocal* l, DefId incomingDef, bool isCompoundAssignment);
+    DefId visitLValue(DfgScope* scope, AstExprLocal* l, DefId incomingDef, bool isCompoundAssignment);
-    void visitLValue(DfgScope* scope, AstExprGlobal* g, DefId incomingDef, bool isCompoundAssignment);
+    DefId visitLValue(DfgScope* scope, AstExprGlobal* g, DefId incomingDef, bool isCompoundAssignment);
-    void visitLValue(DfgScope* scope, AstExprIndexName* i, DefId incomingDef);
+    DefId visitLValue(DfgScope* scope, AstExprIndexName* i, DefId incomingDef);
-    void visitLValue(DfgScope* scope, AstExprIndexExpr* i, DefId incomingDef);
+    DefId visitLValue(DfgScope* scope, AstExprIndexExpr* i, DefId incomingDef);
-    void visitLValue(DfgScope* scope, AstExprError* e, DefId incomingDef);
+    DefId visitLValue(DfgScope* scope, AstExprError* e, DefId incomingDef);
 
     void visitType(DfgScope* scope, AstType* t);
     void visitType(DfgScope* scope, AstTypeReference* r);

Analysis/include/Luau/Def.h

@@ -73,6 +73,7 @@ const T* get(DefId def)
 }
 
 bool containsSubscriptedDefinition(DefId def);
+void collectOperands(DefId def, std::vector<DefId>* operands);
 
 struct DefArena
 {

Analysis/src/ConstraintGenerator.cpp

@@ -205,7 +205,7 @@ ScopePtr ConstraintGenerator::childScope(AstNode* node, const ScopePtr& parent)
     return scope;
 }
 
-std::optional<TypeId> ConstraintGenerator::lookup(Scope* scope, DefId def)
+std::optional<TypeId> ConstraintGenerator::lookup(Scope* scope, DefId def, bool prototype)
 {
     if (get<Cell>(def))
         return scope->lookup(def);
@@ -213,22 +213,24 @@ std::optional<TypeId> ConstraintGenerator::lookup(Scope* scope, DefId def)
     {
         if (auto found = scope->lookup(def))
             return *found;
+        else if (!prototype)
+            return std::nullopt;
 
         TypeId res = builtinTypes->neverType;
 
         for (DefId operand : phi->operands)
         {
-            // `scope->lookup(operand)` may return nothing because it could be a phi node of globals, but one of
+            // `scope->lookup(operand)` may return nothing because we only bind a type to that operand
-            // the operand of that global has never been assigned a type, and so it should be an error.
+            // once we've seen that particular `DefId`. In this case, we need to prototype those types
-            // e.g.
+            // and use those at a later time.
-            // ```
+            std::optional<TypeId> ty = lookup(scope, operand, /*prototype*/false);
-            // if foo() then
+            if (!ty)
-            //   g = 5
+            {
-            // end
+                ty = arena->addType(BlockedType{});
-            // -- `g` here is a phi node of the assignment to `g`, or the original revision of `g` before the branch.
+                rootScope->lvalueTypes[operand] = *ty;
-            // ```
+            }
-            TypeId ty = scope->lookup(operand).value_or(builtinTypes->errorRecoveryType());
+
-            res = simplifyUnion(builtinTypes, arena, res, ty).result;
+            res = simplifyUnion(builtinTypes, arena, res, *ty).result;
         }
 
         scope->lvalueTypes[def] = res;
@@ -861,7 +863,7 @@ ControlFlow ConstraintGenerator::visit(const ScopePtr& scope, AstStatFunction* f
     DenseHashSet<Constraint*> excludeList{nullptr};
 
     DefId def = dfg->getDef(function->name);
-    std::optional<TypeId> existingFunctionTy = scope->lookup(def);
+    std::optional<TypeId> existingFunctionTy = lookup(scope.get(), def);
 
     if (AstExprLocal* localName = function->name->as<AstExprLocal>())
     {
@@ -1724,16 +1726,14 @@ Inference ConstraintGenerator::check(const ScopePtr& scope, AstExprGlobal* globa
     /* prepopulateGlobalScope() has already added all global functions to the environment by this point, so any
      * global that is not already in-scope is definitely an unknown symbol.
      */
-    if (auto ty = lookup(scope.get(), def))
+    if (auto ty = lookup(scope.get(), def, /*prototype=*/false))
-        return Inference{*ty, refinementArena.proposition(key, builtinTypes->truthyType)};
-    else if (auto ty = scope->lookup(global->name))
     {
         rootScope->lvalueTypes[def] = *ty;
         return Inference{*ty, refinementArena.proposition(key, builtinTypes->truthyType)};
     }
     else
     {
-        reportError(global->location, UnknownSymbol{global->name.value});
+        reportError(global->location, UnknownSymbol{global->name.value, UnknownSymbol::Binding});
         return Inference{builtinTypes->errorRecoveryType()};
     }
 }
@@ -3110,6 +3110,16 @@ struct GlobalPrepopulator : AstVisitor
 
         return true;
     }
+
+    bool visit(AstType*) override
+    {
+        return true;
+    }
+
+    bool visit(class AstTypePack* node) override
+    {
+        return true;
+    }
 };
 
 void ConstraintGenerator::prepopulateGlobalScope(const ScopePtr& globalScope, AstStatBlock* program)

Analysis/src/DataFlowGraph.cpp

@@ -116,7 +116,7 @@ bool DfgScope::canUpdateDefinition(Symbol symbol) const
     {
         if (current->bindings.find(symbol))
             return true;
-        else if (current->isLoopScope)
+        else if (current->scopeType == DfgScope::Loop)
             return false;
     }
 
@@ -129,7 +129,7 @@ bool DfgScope::canUpdateDefinition(DefId def, const std::string& key) const
     {
         if (auto props = current->props.find(def))
             return true;
-        else if (current->isLoopScope)
+        else if (current->scopeType == DfgScope::Loop)
             return false;
     }
 
@@ -144,6 +144,7 @@ DataFlowGraph DataFlowGraphBuilder::build(AstStatBlock* block, NotNull<InternalE
     builder.handle = handle;
     builder.moduleScope = builder.childScope(nullptr); // nullptr is the root DFG scope.
     builder.visitBlockWithoutChildScope(builder.moduleScope, block);
+    builder.resolveCaptures();
 
     if (FFlag::DebugLuauFreezeArena)
     {
@@ -154,9 +155,27 @@ DataFlowGraph DataFlowGraphBuilder::build(AstStatBlock* block, NotNull<InternalE
     return std::move(builder.graph);
 }
 
-DfgScope* DataFlowGraphBuilder::childScope(DfgScope* scope, bool isLoopScope)
+void DataFlowGraphBuilder::resolveCaptures()
 {
-    return scopes.emplace_back(new DfgScope{scope, isLoopScope}).get();
+    for (const auto& [_, capture] : captures)
+    {
+        std::vector<DefId> operands;
+        for (size_t i = capture.versionOffset; i < capture.allVersions.size(); ++i)
+            collectOperands(capture.allVersions[i], &operands);
+
+        for (DefId captureDef : capture.captureDefs)
+        {
+            Phi* phi = const_cast<Phi*>(get<Phi>(captureDef));
+            LUAU_ASSERT(phi);
+            LUAU_ASSERT(phi->operands.empty());
+            phi->operands = operands;
+        }
+    }
+}
+
+DfgScope* DataFlowGraphBuilder::childScope(DfgScope* scope, DfgScope::ScopeType scopeType)
+{
+    return scopes.emplace_back(new DfgScope{scope, scopeType}).get();
 }
 
 void DataFlowGraphBuilder::join(DfgScope* p, DfgScope* a, DfgScope* b)
@@ -227,24 +246,44 @@ void DataFlowGraphBuilder::joinProps(DfgScope::Props& p, const DfgScope::Props&
 
 DefId DataFlowGraphBuilder::lookup(DfgScope* scope, Symbol symbol)
 {
-    if (auto found = scope->lookup(symbol))
+    for (DfgScope* current = scope; current; current = current->parent)
-        return *found;
-    else
     {
-        DefId result = defArena->freshCell();
+        if (auto found = current->bindings.find(symbol))
-        if (symbol.local)
+            return NotNull{*found};
-            scope->bindings[symbol] = result;
+        else if (current->scopeType == DfgScope::Function)
-        else
+        {
-            moduleScope->bindings[symbol] = result;
+            FunctionCapture& capture = captures[symbol];
-        return result;
+            DefId captureDef = defArena->phi({});
+            capture.captureDefs.push_back(captureDef);
+            scope->bindings[symbol] = captureDef;
+            return NotNull{captureDef};
+        }
     }
+
+    DefId result = defArena->freshCell();
+    scope->bindings[symbol] = result;
+    captures[symbol].allVersions.push_back(result);
+    return result;
 }
 
 DefId DataFlowGraphBuilder::lookup(DfgScope* scope, DefId def, const std::string& key)
 {
-    if (auto found = scope->lookup(def, key))
+    for (DfgScope* current = scope; current; current = current->parent)
-        return *found;
+    {
-    else if (auto phi = get<Phi>(def))
+        if (auto props = current->props.find(def))
+        {
+            if (auto it = props->find(key); it != props->end())
+                return NotNull{it->second};
+        }
+        else if (auto phi = get<Phi>(def); phi && phi->operands.empty()) // Unresolved phi nodes
+        {
+            DefId result = defArena->freshCell();
+            scope->props[def][key] = result;
+            return result;
+        }
+    }
+
+    if (auto phi = get<Phi>(def))
     {
         std::vector<DefId> defs;
         for (DefId operand : phi->operands)
@@ -361,7 +400,7 @@ ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatIf* i)
 ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatWhile* w)
 {
     // TODO(controlflow): entry point has a back edge from exit point
-    DfgScope* whileScope = childScope(scope, /*isLoopScope=*/true);
+    DfgScope* whileScope = childScope(scope, DfgScope::Loop);
     visitExpr(whileScope, w->condition);
     visit(whileScope, w->body);
 
@@ -373,7 +412,7 @@ ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatWhile* w)
 ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatRepeat* r)
 {
     // TODO(controlflow): entry point has a back edge from exit point
-    DfgScope* repeatScope = childScope(scope, /*isLoopScope=*/true);
+    DfgScope* repeatScope = childScope(scope, DfgScope::Loop);
     visitBlockWithoutChildScope(repeatScope, r->body);
     visitExpr(repeatScope, r->condition);
 
@@ -429,6 +468,7 @@ ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatLocal* l)
         DefId def = defArena->freshCell(subscripted);
         graph.localDefs[local] = def;
         scope->bindings[local] = def;
+        captures[local].allVersions.push_back(def);
     }
 
     return ControlFlow::None;
@@ -436,7 +476,7 @@ ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatLocal* l)
 
 ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatFor* f)
 {
-    DfgScope* forScope = childScope(scope, /*isLoopScope=*/true);
+    DfgScope* forScope = childScope(scope, DfgScope::Loop);
 
     visitExpr(scope, f->from);
     visitExpr(scope, f->to);
@@ -449,6 +489,7 @@ ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatFor* f)
     DefId def = defArena->freshCell();
     graph.localDefs[f->var] = def;
     scope->bindings[f->var] = def;
+    captures[f->var].allVersions.push_back(def);
 
     // TODO(controlflow): entry point has a back edge from exit point
     visit(forScope, f->body);
@@ -460,7 +501,7 @@ ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatFor* f)
 
 ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatForIn* f)
 {
-    DfgScope* forScope = childScope(scope, /*isLoopScope=*/true);
+    DfgScope* forScope = childScope(scope, DfgScope::Loop);
 
     for (AstLocal* local : f->vars)
     {
@@ -470,6 +511,7 @@ ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatForIn* f)
         DefId def = defArena->freshCell();
         graph.localDefs[local] = def;
         forScope->bindings[local] = def;
+        captures[local].allVersions.push_back(def);
     }
 
     // TODO(controlflow): entry point has a back edge from exit point
@@ -527,10 +569,21 @@ ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatFunction* f)
     //
     // which is evidence that references to variables must be a phi node of all possible definitions,
     // but for bug compatibility, we'll assume the same thing here.
-    DefId prototype = defArena->freshCell();
+    visitLValue(scope, f->name, defArena->freshCell());
-    visitLValue(scope, f->name, prototype);
     visitExpr(scope, f->func);
 
+    if (auto local = f->name->as<AstExprLocal>())
+    {
+        // local f
+        // function f()
+        //   if cond() then
+        //     f() -- should reference only the function version and other future version, and nothing prior
+        //   end
+        // end
+        FunctionCapture& capture = captures[local->local];
+        capture.versionOffset = capture.allVersions.size() - 1;
+    }
+
     return ControlFlow::None;
 }
 
@@ -539,6 +592,7 @@ ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatLocalFunction* l
     DefId def = defArena->freshCell();
     graph.localDefs[l->name] = def;
     scope->bindings[l->name] = def;
+    captures[l->name].allVersions.push_back(def);
     visitExpr(scope, l->func);
 
     return ControlFlow::None;
@@ -559,6 +613,7 @@ ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatDeclareGlobal* d
     DefId def = defArena->freshCell();
     graph.declaredDefs[d] = def;
     scope->bindings[d->name] = def;
+    captures[d->name].allVersions.push_back(def);
 
     visitType(scope, d->type);
 
@@ -570,6 +625,7 @@ ControlFlow DataFlowGraphBuilder::visit(DfgScope* scope, AstStatDeclareFunction*
     DefId def = defArena->freshCell();
     graph.declaredDefs[d] = def;
     scope->bindings[d->name] = def;
+    captures[d->name].allVersions.push_back(def);
 
     DfgScope* unreachable = childScope(scope);
     visitGenerics(unreachable, d->generics);
@@ -669,14 +725,9 @@ DataFlowResult DataFlowGraphBuilder::visitExpr(DfgScope* scope, AstExprGroup* gr
 
 DataFlowResult DataFlowGraphBuilder::visitExpr(DfgScope* scope, AstExprLocal* l)
 {
-    // DfgScope::lookup is intentional here: we want to be able to ice.
+    DefId def = lookup(scope, l->local);
-    if (auto def = scope->lookup(l->local))
+    const RefinementKey* key = keyArena->leaf(def);
-    {
+    return {def, key};
-        const RefinementKey* key = keyArena->leaf(*def);
-        return {*def, key};
-    }
-
-    handle->ice("DFG: AstExprLocal came before its declaration?");
 }
 
 DataFlowResult DataFlowGraphBuilder::visitExpr(DfgScope* scope, AstExprGlobal* g)
@@ -723,7 +774,7 @@ DataFlowResult DataFlowGraphBuilder::visitExpr(DfgScope* scope, AstExprIndexExpr
 
 DataFlowResult DataFlowGraphBuilder::visitExpr(DfgScope* scope, AstExprFunction* f)
 {
-    DfgScope* signatureScope = childScope(scope);
+    DfgScope* signatureScope = childScope(scope, DfgScope::Function);
 
     if (AstLocal* self = f->self)
     {
@@ -733,6 +784,7 @@ DataFlowResult DataFlowGraphBuilder::visitExpr(DfgScope* scope, AstExprFunction*
         DefId def = defArena->freshCell();
         graph.localDefs[self] = def;
         signatureScope->bindings[self] = def;
+        captures[self].allVersions.push_back(def);
     }
 
     for (AstLocal* param : f->args)
@@ -743,6 +795,7 @@ DataFlowResult DataFlowGraphBuilder::visitExpr(DfgScope* scope, AstExprFunction*
         DefId def = defArena->freshCell();
         graph.localDefs[param] = def;
         signatureScope->bindings[param] = def;
+        captures[param].allVersions.push_back(def);
     }
 
     if (f->varargAnnotation)
@@ -827,41 +880,46 @@ DataFlowResult DataFlowGraphBuilder::visitExpr(DfgScope* scope, AstExprError* er
 
 void DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExpr* e, DefId incomingDef, bool isCompoundAssignment)
 {
-    if (auto l = e->as<AstExprLocal>())
+    auto go = [&]() {
-        return visitLValue(scope, l, incomingDef, isCompoundAssignment);
+        if (auto l = e->as<AstExprLocal>())
-    else if (auto g = e->as<AstExprGlobal>())
+            return visitLValue(scope, l, incomingDef, isCompoundAssignment);
-        return visitLValue(scope, g, incomingDef, isCompoundAssignment);
+        else if (auto g = e->as<AstExprGlobal>())
-    else if (auto i = e->as<AstExprIndexName>())
+            return visitLValue(scope, g, incomingDef, isCompoundAssignment);
-        return visitLValue(scope, i, incomingDef);
+        else if (auto i = e->as<AstExprIndexName>())
-    else if (auto i = e->as<AstExprIndexExpr>())
+            return visitLValue(scope, i, incomingDef);
-        return visitLValue(scope, i, incomingDef);
+        else if (auto i = e->as<AstExprIndexExpr>())
-    else if (auto error = e->as<AstExprError>())
+            return visitLValue(scope, i, incomingDef);
-        return visitLValue(scope, error, incomingDef);
+        else if (auto error = e->as<AstExprError>())
-    else
+            return visitLValue(scope, error, incomingDef);
-        handle->ice("Unknown AstExpr in DataFlowGraphBuilder::visitLValue");
+        else
+            handle->ice("Unknown AstExpr in DataFlowGraphBuilder::visitLValue");
+    };
+
+    graph.astDefs[e] = go();
 }
 
-void DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExprLocal* l, DefId incomingDef, bool isCompoundAssignment)
+DefId DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExprLocal* l, DefId incomingDef, bool isCompoundAssignment)
 {
     // We need to keep the previous def around for a compound assignment.
     if (isCompoundAssignment)
     {
-        if (auto def = scope->lookup(l->local))
+        DefId def = lookup(scope, l->local);
-            graph.compoundAssignDefs[l] = *def;
+        graph.compoundAssignDefs[l] = def;
     }
 
     // In order to avoid alias tracking, we need to clip the reference to the parent def.
     if (scope->canUpdateDefinition(l->local))
     {
         DefId updated = defArena->freshCell(containsSubscriptedDefinition(incomingDef));
-        graph.astDefs[l] = updated;
         scope->bindings[l->local] = updated;
+        captures[l->local].allVersions.push_back(updated);
+        return updated;
     }
     else
-        visitExpr(scope, static_cast<AstExpr*>(l));
+        return visitExpr(scope, static_cast<AstExpr*>(l)).def;
 }
 
-void DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExprGlobal* g, DefId incomingDef, bool isCompoundAssignment)
+DefId DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExprGlobal* g, DefId incomingDef, bool isCompoundAssignment)
 {
     // We need to keep the previous def around for a compound assignment.
     if (isCompoundAssignment)
@@ -874,28 +932,29 @@ void DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExprGlobal* g, DefId
     if (scope->canUpdateDefinition(g->name))
     {
         DefId updated = defArena->freshCell(containsSubscriptedDefinition(incomingDef));
-        graph.astDefs[g] = updated;
         scope->bindings[g->name] = updated;
+        captures[g->name].allVersions.push_back(updated);
+        return updated;
     }
     else
-        visitExpr(scope, static_cast<AstExpr*>(g));
+        return visitExpr(scope, static_cast<AstExpr*>(g)).def;
 }
 
-void DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExprIndexName* i, DefId incomingDef)
+DefId DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExprIndexName* i, DefId incomingDef)
 {
     DefId parentDef = visitExpr(scope, i->expr).def;
 
     if (scope->canUpdateDefinition(parentDef, i->index.value))
     {
         DefId updated = defArena->freshCell(containsSubscriptedDefinition(incomingDef));
-        graph.astDefs[i] = updated;
         scope->props[parentDef][i->index.value] = updated;
+        return updated;
     }
     else
-        visitExpr(scope, static_cast<AstExpr*>(i));
+        return visitExpr(scope, static_cast<AstExpr*>(i)).def;
 }
 
-void DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExprIndexExpr* i, DefId incomingDef)
+DefId DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExprIndexExpr* i, DefId incomingDef)
 {
     DefId parentDef = visitExpr(scope, i->expr).def;
     visitExpr(scope, i->index);
@@ -905,20 +964,19 @@ void DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExprIndexExpr* i, Def
         if (scope->canUpdateDefinition(parentDef, string->value.data))
         {
             DefId updated = defArena->freshCell(containsSubscriptedDefinition(incomingDef));
-            graph.astDefs[i] = updated;
             scope->props[parentDef][string->value.data] = updated;
+            return updated;
         }
         else
-            visitExpr(scope, static_cast<AstExpr*>(i));
+            return visitExpr(scope, static_cast<AstExpr*>(i)).def;
     }
-
+    else
-    graph.astDefs[i] = defArena->freshCell();
+        return defArena->freshCell(/*subscripted=*/true);
 }
 
-void DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExprError* error, DefId incomingDef)
+DefId DataFlowGraphBuilder::visitLValue(DfgScope* scope, AstExprError* error, DefId incomingDef)
 {
-    DefId def = visitExpr(scope, error).def;
+    return visitExpr(scope, error).def;
-    graph.astDefs[error] = def;
 }
 
 void DataFlowGraphBuilder::visitType(DfgScope* scope, AstType* t)

Analysis/src/Def.cpp

@@ -19,17 +19,13 @@ bool containsSubscriptedDefinition(DefId def)
         return false;
 }
 
-DefId DefArena::freshCell(bool subscripted)
+void collectOperands(DefId def, std::vector<DefId>* operands)
 {
-    return NotNull{allocator.allocate(Def{Cell{subscripted}})};
+    LUAU_ASSERT(operands);
-}
+    if (std::find(operands->begin(), operands->end(), def) != operands->end())
-
-static void collectOperands(DefId def, std::vector<DefId>& operands)
-{
-    if (std::find(operands.begin(), operands.end(), def) != operands.end())
         return;
     else if (get<Cell>(def))
-        operands.push_back(def);
+        operands->push_back(def);
     else if (auto phi = get<Phi>(def))
     {
         for (const Def* operand : phi->operands)
@@ -37,6 +33,11 @@ static void collectOperands(DefId def, std::vector<DefId>& operands)
     }
 }
 
+DefId DefArena::freshCell(bool subscripted)
+{
+    return NotNull{allocator.allocate(Def{Cell{subscripted}})};
+}
+
 DefId DefArena::phi(DefId a, DefId b)
 {
     return phi({a, b});
@@ -46,7 +47,7 @@ DefId DefArena::phi(const std::vector<DefId>& defs)
 {
     std::vector<DefId> operands;
     for (DefId operand : defs)
-        collectOperands(operand, operands);
+        collectOperands(operand, &operands);
 
     // There's no need to allocate a Phi node for a singleton set.
     if (operands.size() == 1)

Analysis/src/Frontend.cpp

@@ -32,11 +32,9 @@ LUAU_FASTINT(LuauTypeInferRecursionLimit)
 LUAU_FASTINT(LuauTarjanChildLimit)
 LUAU_FASTFLAG(LuauInferInNoCheckMode)
 LUAU_FASTFLAGVARIABLE(LuauKnowsTheDataModel3, false)
-LUAU_FASTINTVARIABLE(LuauAutocompleteCheckTimeoutMs, 100) // TODO: Remove with FFlagLuauTypecheckLimitControls
 LUAU_FASTFLAGVARIABLE(DebugLuauDeferredConstraintResolution, false)
 LUAU_FASTFLAGVARIABLE(DebugLuauLogSolverToJson, false)
 LUAU_FASTFLAGVARIABLE(DebugLuauReadWriteProperties, false)
-LUAU_FASTFLAGVARIABLE(LuauTypecheckLimitControls, false)
 LUAU_FASTFLAGVARIABLE(CorrectEarlyReturnInMarkDirty, false)
 LUAU_FASTFLAGVARIABLE(LuauDefinitionFileSetModuleName, false)
 
@@ -902,82 +900,41 @@ void Frontend::checkBuildQueueItem(BuildQueueItem& item)
 
     TypeCheckLimits typeCheckLimits;
 
-    if (FFlag::LuauTypecheckLimitControls)
+    if (item.options.moduleTimeLimitSec)
+        typeCheckLimits.finishTime = TimeTrace::getClock() + *item.options.moduleTimeLimitSec;
+    else
+        typeCheckLimits.finishTime = std::nullopt;
+
+    // TODO: This is a dirty ad hoc solution for autocomplete timeouts
+    // We are trying to dynamically adjust our existing limits to lower total typechecking time under the limit
+    // so that we'll have type information for the whole file at lower quality instead of a full abort in the middle
+    if (item.options.applyInternalLimitScaling)
     {
-        if (item.options.moduleTimeLimitSec)
+        if (FInt::LuauTarjanChildLimit > 0)
-            typeCheckLimits.finishTime = TimeTrace::getClock() + *item.options.moduleTimeLimitSec;
+            typeCheckLimits.instantiationChildLimit = std::max(1, int(FInt::LuauTarjanChildLimit * sourceNode.autocompleteLimitsMult));
         else
-            typeCheckLimits.finishTime = std::nullopt;
+            typeCheckLimits.instantiationChildLimit = std::nullopt;
 
-        // TODO: This is a dirty ad hoc solution for autocomplete timeouts
+        if (FInt::LuauTypeInferIterationLimit > 0)
-        // We are trying to dynamically adjust our existing limits to lower total typechecking time under the limit
+            typeCheckLimits.unifierIterationLimit = std::max(1, int(FInt::LuauTypeInferIterationLimit * sourceNode.autocompleteLimitsMult));
-        // so that we'll have type information for the whole file at lower quality instead of a full abort in the middle
+        else
-        if (item.options.applyInternalLimitScaling)
+            typeCheckLimits.unifierIterationLimit = std::nullopt;
-        {
-            if (FInt::LuauTarjanChildLimit > 0)
-                typeCheckLimits.instantiationChildLimit = std::max(1, int(FInt::LuauTarjanChildLimit * sourceNode.autocompleteLimitsMult));
-            else
-                typeCheckLimits.instantiationChildLimit = std::nullopt;
-
-            if (FInt::LuauTypeInferIterationLimit > 0)
-                typeCheckLimits.unifierIterationLimit = std::max(1, int(FInt::LuauTypeInferIterationLimit * sourceNode.autocompleteLimitsMult));
-            else
-                typeCheckLimits.unifierIterationLimit = std::nullopt;
-        }
-
-        typeCheckLimits.cancellationToken = item.options.cancellationToken;
     }
 
+    typeCheckLimits.cancellationToken = item.options.cancellationToken;
+
     if (item.options.forAutocomplete)
     {
-        double autocompleteTimeLimit = FInt::LuauAutocompleteCheckTimeoutMs / 1000.0;
-
-        if (!FFlag::LuauTypecheckLimitControls)
-        {
-            // The autocomplete typecheck is always in strict mode with DM awareness
-            // to provide better type information for IDE features
-
-            if (autocompleteTimeLimit != 0.0)
-                typeCheckLimits.finishTime = TimeTrace::getClock() + autocompleteTimeLimit;
-            else
-                typeCheckLimits.finishTime = std::nullopt;
-
-            // TODO: This is a dirty ad hoc solution for autocomplete timeouts
-            // We are trying to dynamically adjust our existing limits to lower total typechecking time under the limit
-            // so that we'll have type information for the whole file at lower quality instead of a full abort in the middle
-            if (FInt::LuauTarjanChildLimit > 0)
-                typeCheckLimits.instantiationChildLimit = std::max(1, int(FInt::LuauTarjanChildLimit * sourceNode.autocompleteLimitsMult));
-            else
-                typeCheckLimits.instantiationChildLimit = std::nullopt;
-
-            if (FInt::LuauTypeInferIterationLimit > 0)
-                typeCheckLimits.unifierIterationLimit = std::max(1, int(FInt::LuauTypeInferIterationLimit * sourceNode.autocompleteLimitsMult));
-            else
-                typeCheckLimits.unifierIterationLimit = std::nullopt;
-
-            typeCheckLimits.cancellationToken = item.options.cancellationToken;
-        }
-
         // The autocomplete typecheck is always in strict mode with DM awareness to provide better type information for IDE features
         ModulePtr moduleForAutocomplete = check(sourceModule, Mode::Strict, requireCycles, environmentScope, /*forAutocomplete*/ true,
             /*recordJsonLog*/ false, typeCheckLimits);
 
         double duration = getTimestamp() - timestamp;
 
-        if (FFlag::LuauTypecheckLimitControls)
+        moduleForAutocomplete->checkDurationSec = duration;
-        {
-            moduleForAutocomplete->checkDurationSec = duration;
 
-            if (item.options.moduleTimeLimitSec && item.options.applyInternalLimitScaling)
+        if (item.options.moduleTimeLimitSec && item.options.applyInternalLimitScaling)
-                applyInternalLimitScaling(sourceNode, moduleForAutocomplete, *item.options.moduleTimeLimitSec);
+            applyInternalLimitScaling(sourceNode, moduleForAutocomplete, *item.options.moduleTimeLimitSec);
-        }
-        else
-        {
-            if (moduleForAutocomplete->timeout)
-                sourceNode.autocompleteLimitsMult = sourceNode.autocompleteLimitsMult / 2.0;
-            else if (duration < autocompleteTimeLimit / 2.0)
-                sourceNode.autocompleteLimitsMult = std::min(sourceNode.autocompleteLimitsMult * 2.0, 1.0);
-        }
 
         item.stats.timeCheck += duration;
         item.stats.filesStrict += 1;
@@ -986,29 +943,16 @@ void Frontend::checkBuildQueueItem(BuildQueueItem& item)
         return;
     }
 
-    if (!FFlag::LuauTypecheckLimitControls)
-    {
-        typeCheckLimits.cancellationToken = item.options.cancellationToken;
-    }
-
     ModulePtr module = check(sourceModule, mode, requireCycles, environmentScope, /*forAutocomplete*/ false, item.recordJsonLog, typeCheckLimits);
 
-    if (FFlag::LuauTypecheckLimitControls)
+    double duration = getTimestamp() - timestamp;
-    {
-        double duration = getTimestamp() - timestamp;
 
-        module->checkDurationSec = duration;
+    module->checkDurationSec = duration;
 
-        if (item.options.moduleTimeLimitSec && item.options.applyInternalLimitScaling)
+    if (item.options.moduleTimeLimitSec && item.options.applyInternalLimitScaling)
-            applyInternalLimitScaling(sourceNode, module, *item.options.moduleTimeLimitSec);
+        applyInternalLimitScaling(sourceNode, module, *item.options.moduleTimeLimitSec);
-
-        item.stats.timeCheck += duration;
-    }
-    else
-    {
-        item.stats.timeCheck += getTimestamp() - timestamp;
-    }
 
+    item.stats.timeCheck += duration;
     item.stats.filesStrict += mode == Mode::Strict;
     item.stats.filesNonstrict += mode == Mode::Nonstrict;
 

CLI/Bytecode.cpp

@@ -124,7 +124,7 @@ static bool analyzeFile(const char* name, const unsigned nestingLimit, std::vect
     {
         Luau::BytecodeBuilder bcb;
 
-        compileOrThrow(bcb, source.value(), copts());
+        compileOrThrow(bcb, *source, copts());
 
         const std::string& bytecode = bcb.getBytecode();
 

CodeGen/src/CodeGen.cpp

@@ -42,8 +42,18 @@
 LUAU_FASTFLAGVARIABLE(DebugCodegenNoOpt, false)
 LUAU_FASTFLAGVARIABLE(DebugCodegenOptSize, false)
 LUAU_FASTFLAGVARIABLE(DebugCodegenSkipNumbering, false)
+
+// Per-module IR instruction count limit
 LUAU_FASTINTVARIABLE(CodegenHeuristicsInstructionLimit, 1'048'576)   // 1 M
-LUAU_FASTINTVARIABLE(CodegenHeuristicsBlockLimit, 65'536)            // 64 K
+
+// Per-function IR block limit
+// Current value is based on some member variables being limited to 16 bits
+// Because block check is made before optimization passes and optimization can generate new blocks, limit is lowered 2x
+// The limit will probably be adjusted in the future to avoid performance issues with analysis that's more complex than O(n)
+LUAU_FASTINTVARIABLE(CodegenHeuristicsBlockLimit, 32'768)            // 32 K
+
+// Per-function IR instruction limit
+// Current value is based on some member variables being limited to 16 bits
 LUAU_FASTINTVARIABLE(CodegenHeuristicsBlockInstructionLimit, 65'536) // 64 K
 
 namespace Luau
@@ -104,11 +114,18 @@ static void logPerfFunction(Proto* p, uintptr_t addr, unsigned size)
 }
 
 template<typename AssemblyBuilder>
-static std::optional<NativeProto> createNativeFunction(AssemblyBuilder& build, ModuleHelpers& helpers, Proto* proto)
+static std::optional<NativeProto> createNativeFunction(AssemblyBuilder& build, ModuleHelpers& helpers, Proto* proto, uint32_t& totalIrInstCount)
 {
     IrBuilder ir;
     ir.buildFunctionIr(proto);
 
+    unsigned instCount = unsigned(ir.function.instructions.size());
+
+    if (totalIrInstCount + instCount >= unsigned(FInt::CodegenHeuristicsInstructionLimit.value))
+        return std::nullopt;
+
+    totalIrInstCount += instCount;
+
     if (!lowerFunction(ir, build, helpers, proto, {}, /* stats */ nullptr))
         return std::nullopt;
 
@@ -291,9 +308,13 @@ CodeGenCompilationResult compile(lua_State* L, int idx, unsigned int flags, Comp
     std::vector<NativeProto> results;
     results.reserve(protos.size());
 
+    uint32_t totalIrInstCount = 0;
+
     for (Proto* p : protos)
-        if (std::optional<NativeProto> np = createNativeFunction(build, helpers, p))
+    {
+        if (std::optional<NativeProto> np = createNativeFunction(build, helpers, p, totalIrInstCount))
             results.push_back(*np);
+    }
 
     // Very large modules might result in overflowing a jump offset; in this case we currently abandon the entire module
     if (!build.finalize())

CodeGen/src/CodeGenLower.h

@@ -253,11 +253,6 @@ inline bool lowerIr(A64::AssemblyBuilderA64& build, IrBuilder& ir, const std::ve
 template<typename AssemblyBuilder>
 inline bool lowerFunction(IrBuilder& ir, AssemblyBuilder& build, ModuleHelpers& helpers, Proto* proto, AssemblyOptions options, LoweringStats* stats)
 {
-    helpers.bytecodeInstructionCount += unsigned(ir.function.instructions.size());
-
-    if (helpers.bytecodeInstructionCount >= unsigned(FInt::CodegenHeuristicsInstructionLimit.value))
-        return false;
-
     killUnusedBlocks(ir.function);
 
     unsigned preOptBlockCount = 0;
@@ -268,9 +263,7 @@ inline bool lowerFunction(IrBuilder& ir, AssemblyBuilder& build, ModuleHelpers&
         preOptBlockCount += (block.kind != IrBlockKind::Dead);
         unsigned blockInstructions = block.finish - block.start;
         maxBlockInstructions = std::max(maxBlockInstructions, blockInstructions);
-    };
+    }
-
-    helpers.preOptBlockCount += preOptBlockCount;
 
     // we update stats before checking the heuristic so that even if we bail out
     // our stats include information about the limit that was exceeded.
@@ -280,9 +273,7 @@ inline bool lowerFunction(IrBuilder& ir, AssemblyBuilder& build, ModuleHelpers&
         stats->maxBlockInstructions = maxBlockInstructions;
     }
 
-    // we use helpers.blocksPreOpt instead of stats.blocksPreOpt since
+    if (preOptBlockCount >= unsigned(FInt::CodegenHeuristicsBlockLimit.value))
-    // stats can be null across some code paths.
-    if (helpers.preOptBlockCount >= unsigned(FInt::CodegenHeuristicsBlockLimit.value))
         return false;
 
     if (maxBlockInstructions >= unsigned(FInt::CodegenHeuristicsBlockInstructionLimit.value))

CodeGen/src/EmitCommon.h

@@ -31,9 +31,6 @@ struct ModuleHelpers
 
     // A64
     Label continueCall; // x0: closure
-
-    unsigned bytecodeInstructionCount = 0;
-    unsigned preOptBlockCount = 0;
 };
 
 } // namespace CodeGen

tests/Conformance.test.cpp

@@ -33,6 +33,7 @@ LUAU_FASTFLAG(LuauCodeGenFixByteLower);
 LUAU_FASTFLAG(LuauCompileBufferAnnotation);
 LUAU_FASTFLAG(LuauLoopInterruptFix);
 LUAU_DYNAMIC_FASTFLAG(LuauStricterUtf8);
+LUAU_FASTINT(CodegenHeuristicsInstructionLimit);
 
 static lua_CompileOptions defaultOptions()
 {
@@ -2020,6 +2021,64 @@ TEST_CASE("HugeFunction")
     CHECK(lua_tonumber(L, -1) == 42);
 }
 
+TEST_CASE("IrInstructionLimit")
+{
+    if (!codegen || !luau_codegen_supported())
+        return;
+
+    ScopedFastInt codegenHeuristicsInstructionLimit{FInt::CodegenHeuristicsInstructionLimit, 50'000};
+
+    std::string source;
+
+    // Generate a hundred fat functions
+    for (int fn = 0; fn < 100; fn++)
+    {
+        source += "local function fn" + std::to_string(fn) + "(...)\n";
+        source += "if ... then\n";
+        source += "local p1, p2 = ...\n";
+        source += "local _ = {\n";
+
+        for (int i = 0; i < 100; ++i)
+        {
+            source += "p1*0." + std::to_string(i) + ",";
+            source += "p2+0." + std::to_string(i) + ",";
+        }
+
+        source += "}\n";
+        source += "return _\n";
+        source += "end\n";
+        source += "end\n";
+    }
+
+    StateRef globalState(luaL_newstate(), lua_close);
+    lua_State* L = globalState.get();
+
+    luau_codegen_create(L);
+
+    luaL_openlibs(L);
+    luaL_sandbox(L);
+    luaL_sandboxthread(L);
+
+    size_t bytecodeSize = 0;
+    char* bytecode = luau_compile(source.data(), source.size(), nullptr, &bytecodeSize);
+    int result = luau_load(L, "=HugeFunction", bytecode, bytecodeSize, 0);
+    free(bytecode);
+
+    REQUIRE(result == 0);
+
+    Luau::CodeGen::CompilationStats nativeStats = {};
+    Luau::CodeGen::CodeGenCompilationResult nativeResult = Luau::CodeGen::compile(L, -1, Luau::CodeGen::CodeGen_ColdFunctions, &nativeStats);
+
+    // Limit is not hit immediately, so with some functions compiled it should be a success
+    CHECK(nativeResult != Luau::CodeGen::CodeGenCompilationResult::CodeGenFailed);
+
+    // We should be able to compile at least one of our functions
+    CHECK(nativeStats.functionsCompiled > 0);
+
+    // But because of the limit, not all of them (101 because there's an extra global function)
+    CHECK(nativeStats.functionsCompiled < 101);
+}
+
 TEST_CASE("BytecodeDistributionPerFunctionTest")
 {
     const char* source = R"(

tests/DataFlowGraph.test.cpp

@@ -341,6 +341,7 @@ TEST_CASE_FIXTURE(DataFlowGraphFixture, "property_lookup_on_a_phi_node")
 
     const Phi* phi = get<Phi>(x3);
     REQUIRE(phi);
+    REQUIRE(phi->operands.size() == 2);
     CHECK(phi->operands.at(0) == x1);
     CHECK(phi->operands.at(1) == x2);
 }
@@ -368,6 +369,7 @@ TEST_CASE_FIXTURE(DataFlowGraphFixture, "property_lookup_on_a_phi_node_2")
 
     const Phi* phi = get<Phi>(x3);
     REQUIRE(phi);
+    REQUIRE(phi->operands.size() == 2);
     CHECK(phi->operands.at(0) == x2);
     CHECK(phi->operands.at(1) == x1);
 }
@@ -408,8 +410,154 @@ TEST_CASE_FIXTURE(DataFlowGraphFixture, "property_lookup_on_a_phi_node_3")
 
     const Phi* phi = get<Phi>(x3);
     REQUIRE(phi);
+    REQUIRE(phi->operands.size() == 2);
     CHECK(phi->operands.at(0) == x1);
     CHECK(phi->operands.at(1) == x2);
 }
 
+TEST_CASE_FIXTURE(DataFlowGraphFixture, "function_captures_are_phi_nodes_of_all_versions")
+{
+    dfg(R"(
+        local x = 5
+
+        function f()
+            print(x)
+            x = nil
+        end
+
+        f()
+        x = "five"
+    )");
+
+    DefId x1 = graph->getDef(query<AstStatLocal>(module)->vars.data[0]);
+    DefId x2 = getDef<AstExprLocal, 1>(); // print(x)
+    DefId x3 = getDef<AstExprLocal, 2>(); // x = nil
+    DefId x4 = getDef<AstExprLocal, 3>(); // x = "five"
+
+    CHECK(x1 != x2);
+    CHECK(x2 != x3);
+    CHECK(x3 != x4);
+
+    const Phi* phi = get<Phi>(x2);
+    REQUIRE(phi);
+    REQUIRE(phi->operands.size() == 3);
+    CHECK(phi->operands.at(0) == x1);
+    CHECK(phi->operands.at(1) == x3);
+    CHECK(phi->operands.at(2) == x4);
+}
+
+TEST_CASE_FIXTURE(DataFlowGraphFixture, "function_captures_are_phi_nodes_of_all_versions_properties")
+{
+    dfg(R"(
+        local t = {}
+        t.x = 5
+
+        function f()
+            print(t.x)
+            t.x = nil
+        end
+
+        f()
+        t.x = "five"
+    )");
+
+    DefId x1 = getDef<AstExprIndexName, 1>(); // t.x = 5
+    DefId x2 = getDef<AstExprIndexName, 2>(); // print(t.x)
+    DefId x3 = getDef<AstExprIndexName, 3>(); // t.x = nil
+    DefId x4 = getDef<AstExprIndexName, 4>(); // t.x = "five"
+
+    CHECK(x1 != x2);
+    CHECK(x2 != x3);
+    CHECK(x3 != x4);
+
+    // When a local is referenced within a function, it is not pointer identical.
+    // Instead, it's a phi node of all possible versions, including just one version.
+    DefId t1 = graph->getDef(query<AstStatLocal>(module)->vars.data[0]);
+    DefId t2 = getDef<AstExprLocal, 2>(); // print(t.x)
+
+    const Phi* phi = get<Phi>(t2);
+    REQUIRE(phi);
+    REQUIRE(phi->operands.size() == 1);
+    CHECK(phi->operands.at(0) == t1);
+}
+
+TEST_CASE_FIXTURE(DataFlowGraphFixture, "local_f_which_is_prototyped_enclosed_by_function")
+{
+    dfg(R"(
+        local f
+        function f()
+            if cond() then
+                f()
+            end
+        end
+    )");
+
+    DefId f1 = graph->getDef(query<AstStatLocal>(module)->vars.data[0]);
+    DefId f2 = getDef<AstExprLocal, 1>(); // function f()
+    DefId f3 = getDef<AstExprLocal, 2>(); // f()
+
+    CHECK(f1 != f2);
+    CHECK(f2 != f3);
+
+    const Phi* phi = get<Phi>(f3);
+    REQUIRE(phi);
+    REQUIRE(phi->operands.size() == 1);
+    CHECK(phi->operands.at(0) == f2);
+}
+
+TEST_CASE_FIXTURE(DataFlowGraphFixture, "local_f_which_is_prototyped_enclosed_by_function_has_some_prior_versions")
+{
+    dfg(R"(
+        local f
+        f = 5
+        function f()
+            if cond() then
+                f()
+            end
+        end
+    )");
+
+    DefId f1 = graph->getDef(query<AstStatLocal>(module)->vars.data[0]);
+    DefId f2 = getDef<AstExprLocal, 1>(); // f = 5
+    DefId f3 = getDef<AstExprLocal, 2>(); // function f()
+    DefId f4 = getDef<AstExprLocal, 3>(); // f()
+
+    CHECK(f1 != f2);
+    CHECK(f2 != f3);
+    CHECK(f3 != f4);
+
+    const Phi* phi = get<Phi>(f4);
+    REQUIRE(phi);
+    REQUIRE(phi->operands.size() == 1);
+    CHECK(phi->operands.at(0) == f3);
+}
+
+TEST_CASE_FIXTURE(DataFlowGraphFixture, "local_f_which_is_prototyped_enclosed_by_function_has_some_future_versions")
+{
+    dfg(R"(
+        local f
+        function f()
+            if cond() then
+                f()
+            end
+        end
+        f = 5
+    )");
+
+    DefId f1 = graph->getDef(query<AstStatLocal>(module)->vars.data[0]);
+    DefId f2 = getDef<AstExprLocal, 1>(); // function f()
+    DefId f3 = getDef<AstExprLocal, 2>(); // f()
+    DefId f4 = getDef<AstExprLocal, 3>(); // f = 5
+
+    CHECK(f1 != f2);
+    CHECK(f2 != f3);
+    CHECK(f3 != f4);
+
+    const Phi* phi = get<Phi>(f3);
+    REQUIRE(phi);
+    REQUIRE(phi->operands.size() == 2);
+    CHECK(phi->operands.at(0) == f2);
+    CHECK(phi->operands.at(1) == f4);
+}
+
 TEST_SUITE_END();

tests/RequireByString.test.cpp

@@ -71,6 +71,7 @@ public:
                     luauDirAbs += "/luau";
                 }
 
+
                 if (type == PathType::Relative)
                     return luauDirRel;
                 if (type == PathType::Absolute)

tests/TypeInfer.functions.test.cpp

@@ -736,7 +736,6 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "mutual_recursion")
     )");
 
     LUAU_REQUIRE_NO_ERRORS(result);
-    dumpErrors(result);
 }
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "toposort_doesnt_break_mutual_recursion")

tests/TypeInfer.refinements.test.cpp

@@ -1925,13 +1925,10 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "refine_unknown_to_table")
     // this test is DCR-only as an instance of DCR fixing a bug in the old solver
 
     CheckResult result = check(R"(
-        local idx, val
-
         local function f(a: unknown)
             if typeof(a) == "table" then
                 for i, v in a do
-                    idx = i
+                    return i, v
-                    val = v
                 end
             end
         end
@@ -1939,17 +1936,7 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "refine_unknown_to_table")
 
     LUAU_REQUIRE_NO_ERRORS(result);
 
-    if (FFlag::DebugLuauDeferredConstraintResolution)
+    CHECK_EQ("(unknown) -> (unknown, unknown)", toString(requireType("f")));
-    {
-        // Bug: We do not simplify at the right time
-        CHECK_EQ("unknown?", toString(requireType("idx")));
-        CHECK_EQ("unknown?", toString(requireType("val")));
-    }
-    else
-    {
-        CHECK_EQ("unknown", toString(requireType("idx")));
-        CHECK_EQ("unknown", toString(requireType("val")));
-    }
 }
 
 TEST_CASE_FIXTURE(BuiltinsFixture, "conditional_refinement_should_stay_error_suppressing")

tests/TypeInfer.typestates.test.cpp

@@ -315,4 +315,88 @@ TEST_CASE_FIXTURE(TypeStateFixture, "local_t_is_assigned_a_fresh_table_with_x_as
     CHECK("boolean | number | number | string" == toString(requireType("x")));
 }
 
+TEST_CASE_FIXTURE(TypeStateFixture, "captured_locals_are_unions_of_all_assignments")
+{
+    CheckResult result = check(R"(
+        local x = nil
+
+        function f()
+            print(x)
+            x = "five"
+        end
+
+        x = 5
+        f()
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK("(number | string)?" == toString(requireTypeAtPosition({4, 18})));
+}
+
+TEST_CASE_FIXTURE(TypeStateFixture, "captured_locals_are_unions_of_all_assignments_2")
+{
+    CheckResult result = check(R"(
+        local t = {x = nil}
+
+        function f()
+            print(t.x)
+            t = {x = "five"}
+        end
+
+        t = {x = 5}
+        f()
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK("{ x: nil } | { x: number } | { x: string }" == toString(requireTypeAtPosition({4, 18}), {true}));
+    CHECK("(number | string)?" == toString(requireTypeAtPosition({4, 20})));
+}
+
+TEST_CASE_FIXTURE(TypeStateFixture, "prototyped_recursive_functions")
+{
+    CheckResult result = check(R"(
+        local f
+        function f()
+            if math.random() > 0.5 then
+                f()
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK("(() -> ())?" == toString(requireType("f")));
+}
+
+TEST_CASE_FIXTURE(TypeStateFixture, "prototyped_recursive_functions_but_has_future_assignments")
+{
+    CheckResult result = check(R"(
+        local f
+        function f()
+            if math.random() > 0.5 then
+                f()
+            end
+        end
+        f = 5
+    )");
+
+    LUAU_REQUIRE_ERROR_COUNT(1, result);
+    CHECK("((() -> ()) | number)?" == toString(requireType("f")));
+}
+
+TEST_CASE_FIXTURE(TypeStateFixture, "prototyped_recursive_functions_but_has_previous_assignments")
+{
+    CheckResult result = check(R"(
+        local f
+        f = 5
+        function f()
+            if math.random() > 0.5 then
+                f()
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK("((() -> ()) | number)?" == toString(requireType("f")));
+}
+
 TEST_SUITE_END();

tools/faillist.txt

@@ -268,9 +268,12 @@ ProvisionalTests.typeguard_inference_incomplete
 ProvisionalTests.while_body_are_also_refined
 ProvisionalTests.xpcall_returns_what_f_returns
 RefinementTest.assert_a_to_be_truthy_then_assert_a_to_be_number
+RefinementTest.assert_non_binary_expressions_actually_resolve_constraints
+RefinementTest.correctly_lookup_a_shadowed_local_that_which_was_previously_refined
 RefinementTest.correctly_lookup_property_whose_base_was_previously_refined
 RefinementTest.dataflow_analysis_can_tell_refinements_when_its_appropriate_to_refine_into_nil_or_never
 RefinementTest.discriminate_from_truthiness_of_x
+RefinementTest.either_number_or_string
 RefinementTest.fail_to_refine_a_property_of_subscript_expression
 RefinementTest.falsiness_of_TruthyPredicate_narrows_into_nil
 RefinementTest.function_call_with_colon_after_refining_not_to_be_nil
@@ -288,6 +291,7 @@ RefinementTest.string_not_equal_to_string_or_nil
 RefinementTest.truthy_constraint_on_properties
 RefinementTest.type_annotations_arent_relevant_when_doing_dataflow_analysis
 RefinementTest.type_comparison_ifelse_expression
+RefinementTest.type_guard_narrowed_into_nothingness
 RefinementTest.type_narrow_to_vector
 RefinementTest.typeguard_cast_free_table_to_vector
 RefinementTest.typeguard_in_assert_position
@@ -394,6 +398,7 @@ TableTests.table_unifies_into_map
 TableTests.top_table_type
 TableTests.type_mismatch_on_massive_table_is_cut_short
 TableTests.unification_of_unions_in_a_self_referential_type
+TableTests.unifying_tables_shouldnt_uaf1
 TableTests.used_colon_instead_of_dot
 TableTests.used_dot_instead_of_colon
 TableTests.used_dot_instead_of_colon_but_correctly
@@ -403,6 +408,7 @@ ToDot.function
 ToString.exhaustive_toString_of_cyclic_table
 ToString.free_types
 ToString.named_metatable_toStringNamedFunction
+ToString.no_parentheses_around_cyclic_function_type_in_intersection
 ToString.pick_distinct_names_for_mixed_explicit_and_implicit_generics
 ToString.primitive
 ToString.tostring_unsee_ttv_if_array
@@ -466,6 +472,7 @@ TypeInfer.no_stack_overflow_from_isoptional
 TypeInfer.promote_tail_type_packs
 TypeInfer.recursive_function_that_invokes_itself_with_a_refinement_of_its_parameter
 TypeInfer.recursive_function_that_invokes_itself_with_a_refinement_of_its_parameter_2
+TypeInfer.statements_are_topologically_sorted
 TypeInfer.stringify_nested_unions_with_optionals
 TypeInfer.tc_after_error_recovery_no_replacement_name_in_error
 TypeInfer.type_infer_recursion_limit_no_ice
@@ -481,6 +488,7 @@ TypeInferAnyError.for_in_loop_iterator_is_error
 TypeInferAnyError.for_in_loop_iterator_is_error2
 TypeInferAnyError.for_in_loop_iterator_returns_any
 TypeInferAnyError.intersection_of_any_can_have_props
+TypeInferAnyError.metatable_of_any_can_be_a_table
 TypeInferAnyError.quantify_any_does_not_bind_to_itself
 TypeInferAnyError.replace_every_free_type_when_unifying_a_complex_function_with_any
 TypeInferAnyError.type_error_addition
@@ -502,6 +510,7 @@ TypeInferFunctions.apply_of_lambda_with_inferred_and_explicit_types
 TypeInferFunctions.calling_function_with_anytypepack_doesnt_leak_free_types
 TypeInferFunctions.cannot_hoist_interior_defns_into_signature
 TypeInferFunctions.check_function_bodies
+TypeInferFunctions.complicated_return_types_require_an_explicit_annotation
 TypeInferFunctions.concrete_functions_are_not_supertypes_of_function
 TypeInferFunctions.dont_assert_when_the_tarjan_limit_is_exceeded_during_generalization
 TypeInferFunctions.dont_give_other_overloads_message_if_only_one_argument_matching_overload_exists
@@ -538,7 +547,9 @@ TypeInferFunctions.it_is_ok_to_oversaturate_a_higher_order_function_argument
 TypeInferFunctions.list_all_overloads_if_no_overload_takes_given_argument_count
 TypeInferFunctions.list_only_alternative_overloads_that_match_argument_count
 TypeInferFunctions.luau_subtyping_is_np_hard
+TypeInferFunctions.mutual_recursion
 TypeInferFunctions.no_lossy_function_type
+TypeInferFunctions.num_is_solved_after_num_or_str
 TypeInferFunctions.occurs_check_failure_in_function_return_type
 TypeInferFunctions.other_things_are_not_related_to_function
 TypeInferFunctions.param_1_and_2_both_takes_the_same_generic_but_their_arguments_are_incompatible
@@ -554,6 +565,7 @@ TypeInferFunctions.too_many_arguments
 TypeInferFunctions.too_many_arguments_error_location
 TypeInferFunctions.too_many_return_values_in_parentheses
 TypeInferFunctions.too_many_return_values_no_function
+TypeInferFunctions.toposort_doesnt_break_mutual_recursion
 TypeInferFunctions.vararg_function_is_quantified
 TypeInferLoops.cli_68448_iterators_need_not_accept_nil
 TypeInferLoops.dcr_iteration_explore_raycast_minimization
@@ -598,6 +610,7 @@ TypeInferOOP.dont_suggest_using_colon_rather_than_dot_if_another_overload_works
 TypeInferOOP.dont_suggest_using_colon_rather_than_dot_if_it_wont_help_2
 TypeInferOOP.dont_suggest_using_colon_rather_than_dot_if_not_defined_with_colon
 TypeInferOOP.inferring_hundreds_of_self_calls_should_not_suffocate_memory
+TypeInferOOP.method_depends_on_table
 TypeInferOOP.methods_are_topologically_sorted
 TypeInferOOP.object_constructor_can_refer_to_method_of_self
 TypeInferOOP.promise_type_error_too_complex
@@ -662,6 +675,7 @@ UnionTypes.disallow_less_specific_assign2
 UnionTypes.error_detailed_optional
 UnionTypes.error_detailed_union_all
 UnionTypes.error_detailed_union_part
+UnionTypes.error_takes_optional_arguments
 UnionTypes.generic_function_with_optional_arg
 UnionTypes.index_on_a_union_type_with_missing_property
 UnionTypes.index_on_a_union_type_with_mixed_types
@@ -681,6 +695,7 @@ UnionTypes.optional_union_follow
 UnionTypes.optional_union_functions
 UnionTypes.optional_union_members
 UnionTypes.optional_union_methods
+UnionTypes.return_types_can_be_disjoint
 UnionTypes.table_union_write_indirect
 UnionTypes.unify_unsealed_table_union_check
 UnionTypes.union_of_functions