Sync to upstream/release/651 (#1513)

### What's New?

* Fragment Autocomplete: a new API allows for type checking a small
fragment of code against an existing file, significantly speeding up
autocomplete performance in large files.

### New Solver

* E-Graphs have landed: this is an ongoing approach to make the new type
solver simplify types in a more consistent and principled manner, based
on similar work (see: https://egraphs-good.github.io/).
* Adds support for exporting / local user type functions (previously
they were always exported).
* Fixes a set of bugs in which the new solver will fail to complete
inference for simple expressions with just literals and operators.

### General Updates
* Requiring a path with a ".lua" or ".luau" extension will now have a
bespoke error suggesting to remove said extension.
* Fixes a bug in which whether two `Luau::Symbol`s are equal depends on
whether the new solver is enabled.

---

Internal Contributors:

Co-authored-by: Aaron Weiss <[email protected]>
Co-authored-by: Andy Friesen <[email protected]>
Co-authored-by: David Cope <[email protected]>
Co-authored-by: Hunter Goldstein <[email protected]>
Co-authored-by: Varun Saini <[email protected]>
Co-authored-by: Vighnesh Vijay <[email protected]>
Co-authored-by: Vyacheslav Egorov <[email protected]>

Author: 7 people

Analysis/include/Luau/Autocomplete.h

@@ -1,10 +1,10 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #pragma once
 
+#include "Luau/AutocompleteTypes.h"
 #include "Luau/Location.h"
 #include "Luau/Type.h"
 
-#include <unordered_map>
 #include <string>
 #include <memory>
 #include <optional>
@@ -16,90 +16,8 @@ struct Frontend;
 struct SourceModule;
 struct Module;
 struct TypeChecker;
-
-using ModulePtr = std::shared_ptr<Module>;
-
-enum class AutocompleteContext
-{
-    Unknown,
-    Expression,
-    Statement,
-    Property,
-    Type,
-    Keyword,
-    String,
-};
-
-enum class AutocompleteEntryKind
-{
-    Property,
-    Binding,
-    Keyword,
-    String,
-    Type,
-    Module,
-    GeneratedFunction,
-    RequirePath,
-};
-
-enum class ParenthesesRecommendation
-{
-    None,
-    CursorAfter,
-    CursorInside,
-};
-
-enum class TypeCorrectKind
-{
-    None,
-    Correct,
-    CorrectFunctionResult,
-};
-
-struct AutocompleteEntry
-{
-    AutocompleteEntryKind kind = AutocompleteEntryKind::Property;
-    // Nullopt if kind is Keyword
-    std::optional<TypeId> type = std::nullopt;
-    bool deprecated = false;
-    // Only meaningful if kind is Property.
-    bool wrongIndexType = false;
-    // Set if this suggestion matches the type expected in the context
-    TypeCorrectKind typeCorrect = TypeCorrectKind::None;
-
-    std::optional<const ClassType*> containingClass = std::nullopt;
-    std::optional<const Property*> prop = std::nullopt;
-    std::optional<std::string> documentationSymbol = std::nullopt;
-    Tags tags;
-    ParenthesesRecommendation parens = ParenthesesRecommendation::None;
-    std::optional<std::string> insertText;
-
-    // Only meaningful if kind is Property.
-    bool indexedWithSelf = false;
-};
-
-using AutocompleteEntryMap = std::unordered_map<std::string, AutocompleteEntry>;
-struct AutocompleteResult
-{
-    AutocompleteEntryMap entryMap;
-    std::vector<AstNode*> ancestry;
-    AutocompleteContext context = AutocompleteContext::Unknown;
-
-    AutocompleteResult() = default;
-    AutocompleteResult(AutocompleteEntryMap entryMap, std::vector<AstNode*> ancestry, AutocompleteContext context)
-        : entryMap(std::move(entryMap))
-        , ancestry(std::move(ancestry))
-        , context(context)
-    {
-    }
-};
-
-using ModuleName = std::string;
-using StringCompletionCallback =
-    std::function<std::optional<AutocompleteEntryMap>(std::string tag, std::optional<const ClassType*> ctx, std::optional<std::string> contents)>;
+struct FileResolver;
 
 AutocompleteResult autocomplete(Frontend& frontend, const ModuleName& moduleName, Position position, StringCompletionCallback callback);
 
-constexpr char kGeneratedAnonymousFunctionEntryName[] = "function (anonymous autofilled)";
-
 } // namespace Luau

Analysis/include/Luau/AutocompleteTypes.h

@@ -0,0 +1,92 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+#pragma once
+
+#include "Luau/Ast.h"
+#include "Luau/Type.h"
+
+#include <unordered_map>
+
+namespace Luau
+{
+
+enum class AutocompleteContext
+{
+    Unknown,
+    Expression,
+    Statement,
+    Property,
+    Type,
+    Keyword,
+    String,
+};
+
+enum class AutocompleteEntryKind
+{
+    Property,
+    Binding,
+    Keyword,
+    String,
+    Type,
+    Module,
+    GeneratedFunction,
+    RequirePath,
+};
+
+enum class ParenthesesRecommendation
+{
+    None,
+    CursorAfter,
+    CursorInside,
+};
+
+enum class TypeCorrectKind
+{
+    None,
+    Correct,
+    CorrectFunctionResult,
+};
+
+struct AutocompleteEntry
+{
+    AutocompleteEntryKind kind = AutocompleteEntryKind::Property;
+    // Nullopt if kind is Keyword
+    std::optional<TypeId> type = std::nullopt;
+    bool deprecated = false;
+    // Only meaningful if kind is Property.
+    bool wrongIndexType = false;
+    // Set if this suggestion matches the type expected in the context
+    TypeCorrectKind typeCorrect = TypeCorrectKind::None;
+
+    std::optional<const ClassType*> containingClass = std::nullopt;
+    std::optional<const Property*> prop = std::nullopt;
+    std::optional<std::string> documentationSymbol = std::nullopt;
+    Tags tags;
+    ParenthesesRecommendation parens = ParenthesesRecommendation::None;
+    std::optional<std::string> insertText;
+
+    // Only meaningful if kind is Property.
+    bool indexedWithSelf = false;
+};
+
+using AutocompleteEntryMap = std::unordered_map<std::string, AutocompleteEntry>;
+struct AutocompleteResult
+{
+    AutocompleteEntryMap entryMap;
+    std::vector<AstNode*> ancestry;
+    AutocompleteContext context = AutocompleteContext::Unknown;
+
+    AutocompleteResult() = default;
+    AutocompleteResult(AutocompleteEntryMap entryMap, std::vector<AstNode*> ancestry, AutocompleteContext context)
+        : entryMap(std::move(entryMap))
+        , ancestry(std::move(ancestry))
+        , context(context)
+    {
+    }
+};
+
+using StringCompletionCallback =
+    std::function<std::optional<AutocompleteEntryMap>(std::string tag, std::optional<const ClassType*> ctx, std::optional<std::string> contents)>;
+
+constexpr char kGeneratedAnonymousFunctionEntryName[] = "function (anonymous autofilled)";
+
+} // namespace Luau

Analysis/include/Luau/ConstraintGenerator.h

@@ -5,6 +5,7 @@
 #include "Luau/Constraint.h"
 #include "Luau/ControlFlow.h"
 #include "Luau/DataFlowGraph.h"
+#include "Luau/EqSatSimplification.h"
 #include "Luau/InsertionOrderedMap.h"
 #include "Luau/Module.h"
 #include "Luau/ModuleResolver.h"
@@ -15,7 +16,6 @@
 #include "Luau/TypeFwd.h"
 #include "Luau/TypeUtils.h"
 #include "Luau/Variant.h"
-#include "Luau/Normalize.h"
 
 #include <memory>
 #include <vector>
@@ -109,6 +109,9 @@ struct ConstraintGenerator
 
     // Needed to be able to enable error-suppression preservation for immediate refinements.
     NotNull<Normalizer> normalizer;
+
+    NotNull<Simplifier> simplifier;
+
     // Needed to register all available type functions for execution at later stages.
     NotNull<TypeFunctionRuntime> typeFunctionRuntime;
     // Needed to resolve modules to make 'require' import types properly.
@@ -128,6 +131,7 @@ struct ConstraintGenerator
     ConstraintGenerator(
         ModulePtr module,
         NotNull<Normalizer> normalizer,
+        NotNull<Simplifier> simplifier,
         NotNull<TypeFunctionRuntime> typeFunctionRuntime,
         NotNull<ModuleResolver> moduleResolver,
         NotNull<BuiltinTypes> builtinTypes,
@@ -405,6 +409,7 @@ struct ConstraintGenerator
     TypeId makeUnion(const ScopePtr& scope, Location location, TypeId lhs, TypeId rhs);
     // make an intersect type function of these two types
     TypeId makeIntersect(const ScopePtr& scope, Location location, TypeId lhs, TypeId rhs);
+    void prepopulateGlobalScopeForFragmentTypecheck(const ScopePtr& globalScope, const ScopePtr& resumeScope, AstStatBlock* program);
 
     /** Scan the program for global definitions.
      *
@@ -435,6 +440,8 @@ struct ConstraintGenerator
         const ScopePtr& scope,
         Location location
     );
+
+    TypeId simplifyUnion(const ScopePtr& scope, Location location, TypeId left, TypeId right);
 };
 
 /** Borrow a vector of pointers from a vector of owning pointers to constraints.

Analysis/include/Luau/ConstraintSolver.h

@@ -5,6 +5,7 @@
 #include "Luau/Constraint.h"
 #include "Luau/DataFlowGraph.h"
 #include "Luau/DenseHash.h"
+#include "Luau/EqSatSimplification.h"
 #include "Luau/Error.h"
 #include "Luau/Location.h"
 #include "Luau/Module.h"
@@ -64,6 +65,7 @@ struct ConstraintSolver
     NotNull<BuiltinTypes> builtinTypes;
     InternalErrorReporter iceReporter;
     NotNull<Normalizer> normalizer;
+    NotNull<Simplifier> simplifier;
     NotNull<TypeFunctionRuntime> typeFunctionRuntime;
     // The entire set of constraints that the solver is trying to resolve.
     std::vector<NotNull<Constraint>> constraints;
@@ -117,6 +119,7 @@ struct ConstraintSolver
 
     explicit ConstraintSolver(
         NotNull<Normalizer> normalizer,
+        NotNull<Simplifier> simplifier,
         NotNull<TypeFunctionRuntime> typeFunctionRuntime,
         NotNull<Scope> rootScope,
         std::vector<NotNull<Constraint>> constraints,
@@ -384,6 +387,10 @@ struct ConstraintSolver
      **/
     void reproduceConstraints(NotNull<Scope> scope, const Location& location, const Substitution& subst);
 
+    TypeId simplifyIntersection(NotNull<Scope> scope, Location location, TypeId left, TypeId right);
+    TypeId simplifyIntersection(NotNull<Scope> scope, Location location, std::set<TypeId> parts);
+    TypeId simplifyUnion(NotNull<Scope> scope, Location location, TypeId left, TypeId right);
+
     TypeId errorRecoveryType() const;
     TypePackId errorRecoveryTypePack() const;
 

Analysis/include/Luau/EqSatSimplification.h

@@ -0,0 +1,50 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+
+#pragma once
+
+#include "Luau/TypeFwd.h"
+#include "Luau/NotNull.h"
+#include "Luau/DenseHash.h"
+
+#include <memory>
+#include <optional>
+#include <vector>
+
+namespace Luau
+{
+struct TypeArena;
+}
+
+// The EqSat stuff is pretty template heavy, so we go to some lengths to prevent
+// the complexity from leaking outside its implementation sources.
+namespace Luau::EqSatSimplification
+{
+
+struct Simplifier;
+
+using SimplifierPtr = std::unique_ptr<Simplifier, void (*)(Simplifier*)>;
+
+SimplifierPtr newSimplifier(NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtinTypes);
+
+} // namespace Luau::EqSatSimplification
+
+namespace Luau
+{
+
+struct EqSatSimplificationResult
+{
+    TypeId result;
+
+    // New type function applications that were created by the reduction phase.
+    // We return these so that the ConstraintSolver can know to try to reduce
+    // them.
+    std::vector<TypeId> newTypeFunctions;
+};
+
+using EqSatSimplification::newSimplifier;    // NOLINT: clang-tidy thinks these are unused.  It is incorrect.
+using Luau::EqSatSimplification::Simplifier; // NOLINT
+using Luau::EqSatSimplification::SimplifierPtr;
+
+std::optional<EqSatSimplificationResult> eqSatSimplify(NotNull<Simplifier> simplifier, TypeId ty);
+
+} // namespace Luau