luau/Analysis/include/Luau/Scope.h
vegorov-rbx 42a2805f85
Sync to upstream/release/568 (#865)
* A small subset of control-flow refinements have been added to
recognize type options that are unreachable after a
conditional/unconditional code block. (Fixes
https://github.com/Roblox/luau/issues/356).

Some examples:
```lua
local function f(x: string?)
    if not x then return end

    -- x is 'string' here
end
```
Throwing calls like `error` or `assert(false)` instead of 'return' are
also recognized.
Existing complex refinements like type/typeof and tagged union checks
are expected to work, among others.

To enable this feature, `LuauTinyControlFlowAnalysis` exclusion has to
be removed from `ExperimentalFlags.h`.
If will become enabled unconditionally in the near future.

* Linter has been integrated into the typechecker analysis so that
type-aware lint warnings can work in any mode
`Frontend::lint` methods were deprecated, `Frontend::check` has to be
used instead with `runLintChecks` option set.
Resulting lint warning are located inside `CheckResult`.

* Fixed large performance drop and increased memory consumption when
array is filled at an offset (Fixes
https://github.com/Roblox/luau/issues/590)
* Part of [Type error suppression
RFC](https://github.com/Roblox/luau/blob/master/rfcs/type-error-suppression.md)
was implemented making subtyping checks with `any` type transitive.

---
In our work on the new type-solver:
* `--!nocheck` mode no longer reports type errors
* New solver will not be used for `--!nonstrict` modules until all
issues with strict mode typechecking are fixed
* Added control-flow aware type refinements mentioned earlier

In native code generation:
* `LOP_NAMECALL` has been translated to IR
* `type` and `typeof` builtin fastcalls have been translated to
IR/assembly
* Additional steps were taken towards arm64 support
2023-03-17 12:20:37 -07:00

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C++

// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
#pragma once
#include "Luau/Def.h"
#include "Luau/Location.h"
#include "Luau/NotNull.h"
#include "Luau/Type.h"
#include <unordered_map>
#include <optional>
#include <memory>
namespace Luau
{
struct Scope;
using ScopePtr = std::shared_ptr<Scope>;
struct Binding
{
TypeId typeId;
Location location;
bool deprecated = false;
std::string deprecatedSuggestion;
std::optional<std::string> documentationSymbol;
};
struct Scope
{
explicit Scope(TypePackId returnType); // root scope
explicit Scope(const ScopePtr& parent, int subLevel = 0); // child scope. Parent must not be nullptr.
const ScopePtr parent; // null for the root
// All the children of this scope.
std::vector<NotNull<Scope>> children;
std::unordered_map<Symbol, Binding> bindings;
TypePackId returnType;
std::optional<TypePackId> varargPack;
TypeLevel level;
std::unordered_map<Name, TypeFun> exportedTypeBindings;
std::unordered_map<Name, TypeFun> privateTypeBindings;
std::unordered_map<Name, Location> typeAliasLocations;
std::unordered_map<Name, Location> typeAliasNameLocations;
std::unordered_map<Name, ModuleName> importedModules; // Mapping from the name in the require statement to the internal moduleName.
std::unordered_map<Name, std::unordered_map<Name, TypeFun>> importedTypeBindings;
DenseHashSet<Name> builtinTypeNames{""};
void addBuiltinTypeBinding(const Name& name, const TypeFun& tyFun);
std::optional<TypeId> lookup(Symbol sym) const;
std::optional<TypeId> lookup(DefId def) const;
std::optional<std::pair<Binding*, Scope*>> lookupEx(Symbol sym);
std::optional<TypeFun> lookupType(const Name& name);
std::optional<TypeFun> lookupImportedType(const Name& moduleAlias, const Name& name);
std::unordered_map<Name, TypePackId> privateTypePackBindings;
std::optional<TypePackId> lookupPack(const Name& name);
// WARNING: This function linearly scans for a string key of equal value! It is thus O(n**2)
std::optional<Binding> linearSearchForBinding(const std::string& name, bool traverseScopeChain = true) const;
RefinementMap refinements;
DenseHashMap<const Def*, TypeId> dcrRefinements{nullptr};
void inheritRefinements(const ScopePtr& childScope);
// For mutually recursive type aliases, it's important that
// they use the same types for the same names.
// For instance, in `type Tree<T> { data: T, children: Forest<T> } type Forest<T> = {Tree<T>}`
// we need that the generic type `T` in both cases is the same, so we use a cache.
std::unordered_map<Name, TypeId> typeAliasTypeParameters;
std::unordered_map<Name, TypePackId> typeAliasTypePackParameters;
};
// Returns true iff the left scope encloses the right scope. A Scope* equal to
// nullptr is considered to be the outermost-possible scope.
bool subsumesStrict(Scope* left, Scope* right);
// Returns true if the left scope encloses the right scope, or if they are the
// same scope. As in subsumesStrict(), nullptr is considered to be the
// outermost-possible scope.
bool subsumes(Scope* left, Scope* right);
} // namespace Luau