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luau/Analysis/src/Simplify.cpp
Andy Friesen e25b0a6275
Sync to upstream/release/591 (#1012) 
* Fix a use-after-free bug in the new type cloning algorithm
* Tighten up the type of `coroutine.wrap`. It is now `<A..., R...>(f:
(A...) -> R...) -> ((A...) -> R...)`
* Break `.luaurc` out into a separate library target `Luau.Config`. This
makes it easier for applications to reason about config files without
also depending on the type inference engine.
* Move typechecking limits into `FrontendOptions`. This allows embedders
more finely-grained control over autocomplete's internal time limits.
* Fix stability issue with debugger onprotectederror callback allowing
break in non-yieldable contexts

New solver:

* Initial work toward [Local Type
Inference](0e1082108f/rfcs/local-type-inference.md)
* Introduce a new subtyping test. This will be much nicer than the old
test because it is completely separate both from actual type inference
and from error reporting.

Native code generation:

* Added function to compute iterated dominance frontier
* Optimize barriers in SET_UPVALUE when tag is known
* Cache lua_State::global in a register on A64
* Optimize constant stores in A64 lowering
* Track table array size state to optimize array size checks
* Add split tag/value store into a VM register
* Check that spills can outlive the block only in specific conditions

---------

Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
2023-08-18 11:15:41 -07:00

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// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
#include "Luau/Simplify.h"
#include "Luau/Normalize.h" // TypeIds
#include "Luau/RecursionCounter.h"
#include "Luau/ToString.h"
#include "Luau/TypeArena.h"
#include "Luau/TypeUtils.h"
#include <algorithm>
LUAU_FASTINT(LuauTypeReductionRecursionLimit)
LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
namespace Luau
{
struct TypeSimplifier
{
NotNull<BuiltinTypes> builtinTypes;
NotNull<TypeArena> arena;
std::set<TypeId> blockedTypes;
int recursionDepth = 0;
TypeId mkNegation(TypeId ty);
TypeId intersectFromParts(std::set<TypeId> parts);
TypeId intersectUnionWithType(TypeId unionTy, TypeId right);
TypeId intersectUnions(TypeId left, TypeId right);
TypeId intersectNegatedUnion(TypeId unionTy, TypeId right);
TypeId intersectTypeWithNegation(TypeId a, TypeId b);
TypeId intersectNegations(TypeId a, TypeId b);
TypeId intersectIntersectionWithType(TypeId left, TypeId right);
// Attempt to intersect the two types. Does not recurse. Does not handle
// unions, intersections, or negations.
std::optional<TypeId> basicIntersect(TypeId left, TypeId right);
TypeId intersect(TypeId ty, TypeId discriminant);
TypeId union_(TypeId ty, TypeId discriminant);
TypeId simplify(TypeId ty);
TypeId simplify(TypeId ty, DenseHashSet<TypeId>& seen);
};
// Match the exact type false|nil
static bool isFalsyType(TypeId ty)
{
ty = follow(ty);
const UnionType* ut = get<UnionType>(ty);
if (!ut)
return false;
bool hasFalse = false;
bool hasNil = false;
auto it = begin(ut);
if (it == end(ut))
return false;
TypeId t = follow(*it);
if (auto pt = get<PrimitiveType>(t); pt && pt->type == PrimitiveType::NilType)
hasNil = true;
else if (auto st = get<SingletonType>(t); st && st->variant == BooleanSingleton{false})
hasFalse = true;
else
return false;
++it;
if (it == end(ut))
return false;
t = follow(*it);
if (auto pt = get<PrimitiveType>(t); pt && pt->type == PrimitiveType::NilType)
hasNil = true;
else if (auto st = get<SingletonType>(t); st && st->variant == BooleanSingleton{false})
hasFalse = true;
else
return false;
++it;
if (it != end(ut))
return false;
return hasFalse && hasNil;
}
// Match the exact type ~(false|nil)
bool isTruthyType(TypeId ty)
{
ty = follow(ty);
const NegationType* nt = get<NegationType>(ty);
if (!nt)
return false;
return isFalsyType(nt->ty);
}
Relation flip(Relation rel)
{
switch (rel)
{
case Relation::Subset:
return Relation::Superset;
case Relation::Superset:
return Relation::Subset;
default:
return rel;
}
}
// FIXME: I'm not completely certain that this function is theoretically reasonable.
Relation combine(Relation a, Relation b)
{
switch (a)
{
case Relation::Disjoint:
switch (b)
{
case Relation::Disjoint:
return Relation::Disjoint;
case Relation::Coincident:
return Relation::Superset;
case Relation::Intersects:
return Relation::Intersects;
case Relation::Subset:
return Relation::Intersects;
case Relation::Superset:
return Relation::Intersects;
}
case Relation::Coincident:
switch (b)
{
case Relation::Disjoint:
return Relation::Coincident;
case Relation::Coincident:
return Relation::Coincident;
case Relation::Intersects:
return Relation::Superset;
case Relation::Subset:
return Relation::Coincident;
case Relation::Superset:
return Relation::Intersects;
}
case Relation::Superset:
switch (b)
{
case Relation::Disjoint:
return Relation::Superset;
case Relation::Coincident:
return Relation::Superset;
case Relation::Intersects:
return Relation::Intersects;
case Relation::Subset:
return Relation::Intersects;
case Relation::Superset:
return Relation::Superset;
}
case Relation::Subset:
switch (b)
{
case Relation::Disjoint:
return Relation::Subset;
case Relation::Coincident:
return Relation::Coincident;
case Relation::Intersects:
return Relation::Intersects;
case Relation::Subset:
return Relation::Subset;
case Relation::Superset:
return Relation::Intersects;
}
case Relation::Intersects:
switch (b)
{
case Relation::Disjoint:
return Relation::Intersects;
case Relation::Coincident:
return Relation::Superset;
case Relation::Intersects:
return Relation::Intersects;
case Relation::Subset:
return Relation::Intersects;
case Relation::Superset:
return Relation::Intersects;
}
}
LUAU_UNREACHABLE();
return Relation::Intersects;
}
// Given A & B, what is A & ~B?
Relation invert(Relation r)
{
switch (r)
{
case Relation::Disjoint:
return Relation::Subset;
case Relation::Coincident:
return Relation::Disjoint;
case Relation::Intersects:
return Relation::Intersects;
case Relation::Subset:
return Relation::Disjoint;
case Relation::Superset:
return Relation::Intersects;
}
LUAU_UNREACHABLE();
return Relation::Intersects;
}
static bool isTypeVariable(TypeId ty)
{
return get<FreeType>(ty) || get<GenericType>(ty) || get<BlockedType>(ty) || get<PendingExpansionType>(ty);
}
Relation relate(TypeId left, TypeId right);
Relation relateTables(TypeId left, TypeId right)
{
NotNull<const TableType> leftTable{get<TableType>(left)};
NotNull<const TableType> rightTable{get<TableType>(right)};
LUAU_ASSERT(1 == rightTable->props.size());
// Disjoint props have nothing in common
// t1 with props p1's cannot appear in t2 and t2 with props p2's cannot appear in t1
bool foundPropFromLeftInRight = std::any_of(begin(leftTable->props), end(leftTable->props), [&](auto prop) {
return rightTable->props.find(prop.first) != end(rightTable->props);
});
bool foundPropFromRightInLeft = std::any_of(begin(rightTable->props), end(rightTable->props), [&](auto prop) {
return leftTable->props.find(prop.first) != end(leftTable->props);
});
if (!(foundPropFromLeftInRight || foundPropFromRightInLeft) && leftTable->props.size() >= 1 && rightTable->props.size() >= 1)
return Relation::Disjoint;
const auto [propName, rightProp] = *begin(rightTable->props);
auto it = leftTable->props.find(propName);
if (it == leftTable->props.end())
{
// Every table lacking a property is a supertype of a table having that
// property but the reverse is not true.
return Relation::Superset;
}
const Property leftProp = it->second;
Relation r = relate(leftProp.type(), rightProp.type());
if (r == Relation::Coincident && 1 != leftTable->props.size())
{
// eg {tag: "cat", prop: string} & {tag: "cat"}
return Relation::Subset;
}
else
return r;
}
// A cheap and approximate subtype test
Relation relate(TypeId left, TypeId right)
{
// TODO nice to have: Relate functions of equal argument and return arity
left = follow(left);
right = follow(right);
if (left == right)
return Relation::Coincident;
if (get<UnknownType>(left))
{
if (get<AnyType>(right))
return Relation::Subset;
else if (get<UnknownType>(right))
return Relation::Coincident;
else if (get<ErrorType>(right))
return Relation::Disjoint;
else
return Relation::Superset;
}
if (get<UnknownType>(right))
return flip(relate(right, left));
if (get<AnyType>(left))
{
if (get<AnyType>(right))
return Relation::Coincident;
else
return Relation::Superset;
}
if (get<AnyType>(right))
return flip(relate(right, left));
// Type variables
// * FreeType
// * GenericType
// * BlockedType
// * PendingExpansionType
// Tops and bottoms
// * ErrorType
// * AnyType
// * NeverType
// * UnknownType
// Concrete
// * PrimitiveType
// * SingletonType
// * FunctionType
// * TableType
// * MetatableType
// * ClassType
// * UnionType
// * IntersectionType
// * NegationType
if (isTypeVariable(left) || isTypeVariable(right))
return Relation::Intersects;
if (get<ErrorType>(left))
{
if (get<ErrorType>(right))
return Relation::Coincident;
else if (get<AnyType>(right))
return Relation::Subset;
else
return Relation::Disjoint;
}
if (get<ErrorType>(right))
return flip(relate(right, left));
if (get<NeverType>(left))
{
if (get<NeverType>(right))
return Relation::Coincident;
else
return Relation::Subset;
}
if (get<NeverType>(right))
return flip(relate(right, left));
if (auto ut = get<IntersectionType>(left))
return Relation::Intersects;
else if (auto ut = get<IntersectionType>(right))
return Relation::Intersects;
if (auto ut = get<UnionType>(left))
return Relation::Intersects;
else if (auto ut = get<UnionType>(right))
{
std::vector<Relation> opts;
for (TypeId part : ut)
if (relate(left, part) == Relation::Subset)
return Relation::Subset;
return Relation::Intersects;
}
if (auto rnt = get<NegationType>(right))
{
Relation a = relate(left, rnt->ty);
switch (a)
{
case Relation::Coincident:
// number & ~number
return Relation::Disjoint;
case Relation::Disjoint:
if (get<NegationType>(left))
{
// ~number & ~string
return Relation::Intersects;
}
else
{
// number & ~string
return Relation::Subset;
}
case Relation::Intersects:
// ~(false?) & ~boolean
return Relation::Intersects;
case Relation::Subset:
// "hello" & ~string
return Relation::Disjoint;
case Relation::Superset:
// ~function & ~(false?) -> ~function
// boolean & ~(false?) -> true
// string & ~"hello" -> string & ~"hello"
return Relation::Intersects;
}
}
else if (get<NegationType>(left))
return flip(relate(right, left));
if (auto lp = get<PrimitiveType>(left))
{
if (auto rp = get<PrimitiveType>(right))
{
if (lp->type == rp->type)
return Relation::Coincident;
else
return Relation::Disjoint;
}
if (auto rs = get<SingletonType>(right))
{
if (lp->type == PrimitiveType::String && rs->variant.get_if<StringSingleton>())
return Relation::Superset;
else if (lp->type == PrimitiveType::Boolean && rs->variant.get_if<BooleanSingleton>())
return Relation::Superset;
else
return Relation::Disjoint;
}
if (lp->type == PrimitiveType::Function)
{
if (get<FunctionType>(right))
return Relation::Superset;
else
return Relation::Disjoint;
}
if (lp->type == PrimitiveType::Table)
{
if (get<TableType>(right))
return Relation::Superset;
else
return Relation::Disjoint;
}
if (get<FunctionType>(right) || get<TableType>(right) || get<MetatableType>(right) || get<ClassType>(right))
return Relation::Disjoint;
}
if (auto ls = get<SingletonType>(left))
{
if (get<FunctionType>(right) || get<TableType>(right) || get<MetatableType>(right) || get<ClassType>(right))
return Relation::Disjoint;
if (get<PrimitiveType>(right))
return flip(relate(right, left));
if (auto rs = get<SingletonType>(right))
{
if (ls->variant == rs->variant)
return Relation::Coincident;
else
return Relation::Disjoint;
}
}
if (get<FunctionType>(left))
{
if (auto rp = get<PrimitiveType>(right))
{
if (rp->type == PrimitiveType::Function)
return Relation::Subset;
else
return Relation::Disjoint;
}
else
return Relation::Intersects;
}
if (auto lt = get<TableType>(left))
{
if (auto rp = get<PrimitiveType>(right))
{
if (rp->type == PrimitiveType::Table)
return Relation::Subset;
else
return Relation::Disjoint;
}
else if (auto rt = get<TableType>(right))
{
// TODO PROBABLY indexers and metatables.
if (1 == rt->props.size())
{
Relation r = relateTables(left, right);
/*
* A reduction of these intersections is certainly possible, but
* it would require minting new table types. Also, I don't think
* it's super likely for this to arise from a refinement.
*
* Time will tell!
*
* ex we simplify this
* {tag: string} & {tag: "cat"}
* but not this
* {tag: string, prop: number} & {tag: "cat"}
*/
if (lt->props.size() > 1 && r == Relation::Superset)
return Relation::Intersects;
else
return r;
}
else if (1 == lt->props.size())
return flip(relate(right, left));
else
return Relation::Intersects;
}
// TODO metatables
return Relation::Disjoint;
}
if (auto ct = get<ClassType>(left))
{
if (auto rct = get<ClassType>(right))
{
if (isSubclass(ct, rct))
return Relation::Subset;
else if (isSubclass(rct, ct))
return Relation::Superset;
else
return Relation::Disjoint;
}
return Relation::Disjoint;
}
return Relation::Intersects;
}
TypeId TypeSimplifier::mkNegation(TypeId ty)
{
TypeId result = nullptr;
if (ty == builtinTypes->truthyType)
result = builtinTypes->falsyType;
else if (ty == builtinTypes->falsyType)
result = builtinTypes->truthyType;
else if (auto ntv = get<NegationType>(ty))
result = follow(ntv->ty);
else
result = arena->addType(NegationType{ty});
return result;
}
TypeId TypeSimplifier::intersectFromParts(std::set<TypeId> parts)
{
if (0 == parts.size())
return builtinTypes->neverType;
else if (1 == parts.size())
return *begin(parts);
{
auto it = begin(parts);
while (it != end(parts))
{
TypeId t = follow(*it);
auto copy = it;
++it;
if (auto ut = get<IntersectionType>(t))
{
for (TypeId part : ut)
parts.insert(part);
parts.erase(copy);
}
}
}
std::set<TypeId> newParts;
/*
* It is possible that the parts of the passed intersection are themselves
* reducable.
*
* eg false & boolean
*
* We do a comparison between each pair of types and look for things that we
* can elide.
*/
for (TypeId part : parts)
{
if (newParts.empty())
{
newParts.insert(part);
continue;
}
auto it = begin(newParts);
while (it != end(newParts))
{
TypeId p = *it;
switch (relate(part, p))
{
case Relation::Disjoint:
// eg boolean & string
return builtinTypes->neverType;
case Relation::Subset:
{
/* part is a subset of p. Remove p from the set and replace it
* with part.
*
* eg boolean & true
*/
auto saveIt = it;
++it;
newParts.erase(saveIt);
continue;
}
case Relation::Coincident:
case Relation::Superset:
{
/* part is coincident or a superset of p. We do not need to
* include part in the final intersection.
*
* ex true & boolean
*/
++it;
continue;
}
case Relation::Intersects:
{
/* It's complicated! A simplification may still be possible,
* but we have to pull the types apart to figure it out.
*
* ex boolean & ~false
*/
std::optional<TypeId> simplified = basicIntersect(part, p);
auto saveIt = it;
++it;
if (simplified)
{
newParts.erase(saveIt);
newParts.insert(*simplified);
}
else
newParts.insert(part);
continue;
}
}
}
}
if (0 == newParts.size())
return builtinTypes->neverType;
else if (1 == newParts.size())
return *begin(newParts);
else
return arena->addType(IntersectionType{std::vector<TypeId>{begin(newParts), end(newParts)}});
}
TypeId TypeSimplifier::intersectUnionWithType(TypeId left, TypeId right)
{
const UnionType* leftUnion = get<UnionType>(left);
LUAU_ASSERT(leftUnion);
bool changed = false;
std::set<TypeId> newParts;
for (TypeId part : leftUnion)
{
TypeId simplified = intersect(right, part);
changed |= simplified != part;
if (get<NeverType>(simplified))
{
changed = true;
continue;
}
newParts.insert(simplified);
}
if (!changed)
return left;
else if (newParts.empty())
return builtinTypes->neverType;
else if (newParts.size() == 1)
return *begin(newParts);
else
return arena->addType(UnionType{std::vector<TypeId>(begin(newParts), end(newParts))});
}
TypeId TypeSimplifier::intersectUnions(TypeId left, TypeId right)
{
const UnionType* leftUnion = get<UnionType>(left);
LUAU_ASSERT(leftUnion);
const UnionType* rightUnion = get<UnionType>(right);
LUAU_ASSERT(rightUnion);
std::set<TypeId> newParts;
for (TypeId leftPart : leftUnion)
{
for (TypeId rightPart : rightUnion)
{
TypeId simplified = intersect(leftPart, rightPart);
if (get<NeverType>(simplified))
continue;
newParts.insert(simplified);
}
}
if (newParts.empty())
return builtinTypes->neverType;
else if (newParts.size() == 1)
return *begin(newParts);
else
return arena->addType(UnionType{std::vector<TypeId>(begin(newParts), end(newParts))});
}
TypeId TypeSimplifier::intersectNegatedUnion(TypeId left, TypeId right)
{
// ~(A | B) & C
// (~A & C) & (~B & C)
const NegationType* leftNegation = get<NegationType>(left);
LUAU_ASSERT(leftNegation);
TypeId negatedTy = follow(leftNegation->ty);
const UnionType* negatedUnion = get<UnionType>(negatedTy);
LUAU_ASSERT(negatedUnion);
bool changed = false;
std::set<TypeId> newParts;
for (TypeId part : negatedUnion)
{
Relation r = relate(part, right);
switch (r)
{
case Relation::Disjoint:
// If A is disjoint from B, then ~A & B is just B.
//
// ~(false?) & true
// (~false & true) & (~nil & true)
// true & true
newParts.insert(right);
break;
case Relation::Coincident:
// If A is coincident with or a superset of B, then ~A & B is never.
//
// ~(false?) & false
// (~false & false) & (~nil & false)
// never & false
//
// fallthrough
case Relation::Superset:
// If A is a superset of B, then ~A & B is never.
//
// ~(boolean | nil) & true
// (~boolean & true) & (~boolean & nil)
// never & nil
return builtinTypes->neverType;
case Relation::Subset:
case Relation::Intersects:
// If A is a subset of B, then ~A & B is a bit more complicated. We need to think harder.
//
// ~(false?) & boolean
// (~false & boolean) & (~nil & boolean)
// true & boolean
TypeId simplified = intersectTypeWithNegation(mkNegation(part), right);
changed |= simplified != right;
if (get<NeverType>(simplified))
changed = true;
else
newParts.insert(simplified);
break;
}
}
if (!changed)
return right;
else
return intersectFromParts(std::move(newParts));
}
TypeId TypeSimplifier::intersectTypeWithNegation(TypeId left, TypeId right)
{
const NegationType* leftNegation = get<NegationType>(left);
LUAU_ASSERT(leftNegation);
TypeId negatedTy = follow(leftNegation->ty);
if (negatedTy == right)
return builtinTypes->neverType;
if (auto ut = get<UnionType>(negatedTy))
{
// ~(A | B) & C
// (~A & C) & (~B & C)
bool changed = false;
std::set<TypeId> newParts;
for (TypeId part : ut)
{
Relation r = relate(part, right);
switch (r)
{
case Relation::Coincident:
// ~(false?) & nil
// (~false & nil) & (~nil & nil)
// nil & never
//
// fallthrough
case Relation::Superset:
// ~(boolean | string) & true
// (~boolean & true) & (~boolean & string)
// never & string
return builtinTypes->neverType;
case Relation::Disjoint:
// ~nil & boolean
newParts.insert(right);
break;
case Relation::Subset:
// ~false & boolean
// fallthrough
case Relation::Intersects:
// FIXME: The mkNegation here is pretty unfortunate.
// Memoizing this will probably be important.
changed = true;
newParts.insert(right);
newParts.insert(mkNegation(part));
}
}
if (!changed)
return right;
else
return intersectFromParts(std::move(newParts));
}
if (auto rightUnion = get<UnionType>(right))
{
// ~A & (B | C)
bool changed = false;
std::set<TypeId> newParts;
for (TypeId part : rightUnion)
{
Relation r = relate(negatedTy, part);
switch (r)
{
case Relation::Coincident:
changed = true;
continue;
case Relation::Disjoint:
newParts.insert(part);
break;
case Relation::Superset:
changed = true;
continue;
case Relation::Subset:
// fallthrough
case Relation::Intersects:
changed = true;
newParts.insert(arena->addType(IntersectionType{{left, part}}));
}
}
if (!changed)
return right;
else if (0 == newParts.size())
return builtinTypes->neverType;
else if (1 == newParts.size())
return *begin(newParts);
else
return arena->addType(UnionType{std::vector<TypeId>{begin(newParts), end(newParts)}});
}
if (auto pt = get<PrimitiveType>(right); pt && pt->type == PrimitiveType::Boolean)
{
if (auto st = get<SingletonType>(negatedTy))
{
if (st->variant == BooleanSingleton{true})
return builtinTypes->falseType;
else if (st->variant == BooleanSingleton{false})
return builtinTypes->trueType;
else
// boolean & ~"hello"
return builtinTypes->booleanType;
}
}
Relation r = relate(negatedTy, right);
switch (r)
{
case Relation::Disjoint:
// ~boolean & string
return right;
case Relation::Coincident:
// ~string & string
// fallthrough
case Relation::Superset:
// ~string & "hello"
return builtinTypes->neverType;
case Relation::Subset:
// ~string & unknown
// ~"hello" & string
// fallthrough
case Relation::Intersects:
// ~("hello" | boolean) & string
// fallthrough
default:
return arena->addType(IntersectionType{{left, right}});
}
}
TypeId TypeSimplifier::intersectNegations(TypeId left, TypeId right)
{
const NegationType* leftNegation = get<NegationType>(left);
LUAU_ASSERT(leftNegation);
if (get<UnionType>(follow(leftNegation->ty)))
return intersectNegatedUnion(left, right);
const NegationType* rightNegation = get<NegationType>(right);
LUAU_ASSERT(rightNegation);
if (get<UnionType>(follow(rightNegation->ty)))
return intersectNegatedUnion(right, left);
Relation r = relate(leftNegation->ty, rightNegation->ty);
switch (r)
{
case Relation::Coincident:
// ~true & ~true
return left;
case Relation::Subset:
// ~true & ~boolean
return right;
case Relation::Superset:
// ~boolean & ~true
return left;
case Relation::Intersects:
case Relation::Disjoint:
default:
// ~boolean & ~string
return arena->addType(IntersectionType{{left, right}});
}
}
TypeId TypeSimplifier::intersectIntersectionWithType(TypeId left, TypeId right)
{
const IntersectionType* leftIntersection = get<IntersectionType>(left);
LUAU_ASSERT(leftIntersection);
bool changed = false;
std::set<TypeId> newParts;
for (TypeId part : leftIntersection)
{
Relation r = relate(part, right);
switch (r)
{
case Relation::Disjoint:
return builtinTypes->neverType;
case Relation::Coincident:
newParts.insert(part);
continue;
case Relation::Subset:
newParts.insert(part);
continue;
case Relation::Superset:
newParts.insert(right);
changed = true;
continue;
default:
newParts.insert(part);
newParts.insert(right);
changed = true;
continue;
}
}
// It is sometimes the case that an intersection operation will result in
// clipping a free type from the result.
//
// eg (number & 'a) & string --> never
//
// We want to only report the free types that are part of the result.
for (TypeId part : newParts)
{
if (isTypeVariable(part))
blockedTypes.insert(part);
}
if (!changed)
return left;
return intersectFromParts(std::move(newParts));
}
std::optional<TypeId> TypeSimplifier::basicIntersect(TypeId left, TypeId right)
{
if (get<AnyType>(left))
return right;
if (get<AnyType>(right))
return left;
if (get<NeverType>(left))
return left;
if (get<NeverType>(right))
return right;
if (auto pt = get<PrimitiveType>(left); pt && pt->type == PrimitiveType::Boolean)
{
if (auto st = get<SingletonType>(right); st && st->variant.get_if<BooleanSingleton>())
return right;
if (auto nt = get<NegationType>(right))
{
if (auto st = get<SingletonType>(follow(nt->ty)); st && st->variant.get_if<BooleanSingleton>())
{
if (st->variant == BooleanSingleton{true})
return builtinTypes->falseType;
else
return builtinTypes->trueType;
}
}
}
else if (auto pt = get<PrimitiveType>(right); pt && pt->type == PrimitiveType::Boolean)
{
if (auto st = get<SingletonType>(left); st && st->variant.get_if<BooleanSingleton>())
return left;
if (auto nt = get<NegationType>(left))
{
if (auto st = get<SingletonType>(follow(nt->ty)); st && st->variant.get_if<BooleanSingleton>())
{
if (st->variant == BooleanSingleton{true})
return builtinTypes->falseType;
else
return builtinTypes->trueType;
}
}
}
if (const auto [lt, rt] = get2<TableType, TableType>(left, right); lt && rt)
{
if (1 == lt->props.size())
{
const auto [propName, leftProp] = *begin(lt->props);
auto it = rt->props.find(propName);
if (it != rt->props.end())
{
Relation r = relate(leftProp.type(), it->second.type());
switch (r)
{
case Relation::Disjoint:
return builtinTypes->neverType;
case Relation::Coincident:
return right;
default:
break;
}
}
}
else if (1 == rt->props.size())
return basicIntersect(right, left);
}
Relation relation = relate(left, right);
if (left == right || Relation::Coincident == relation)
return left;
if (relation == Relation::Disjoint)
return builtinTypes->neverType;
else if (relation == Relation::Subset)
return left;
else if (relation == Relation::Superset)
return right;
return std::nullopt;
}
TypeId TypeSimplifier::intersect(TypeId left, TypeId right)
{
RecursionLimiter rl(&recursionDepth, 15);
left = simplify(left);
right = simplify(right);
if (get<AnyType>(left))
return right;
if (get<AnyType>(right))
return left;
if (get<NeverType>(left))
return left;
if (get<NeverType>(right))
return right;
if (auto lf = get<FreeType>(left))
{
Relation r = relate(lf->upperBound, right);
if (r == Relation::Subset || r == Relation::Coincident)
return left;
}
else if (auto rf = get<FreeType>(right))
{
Relation r = relate(left, rf->upperBound);
if (r == Relation::Superset || r == Relation::Coincident)
return right;
}
if (isTypeVariable(left))
{
blockedTypes.insert(left);
return arena->addType(IntersectionType{{left, right}});
}
if (isTypeVariable(right))
{
blockedTypes.insert(right);
return arena->addType(IntersectionType{{left, right}});
}
if (auto ut = get<UnionType>(left))
{
if (get<UnionType>(right))
return intersectUnions(left, right);
else
return intersectUnionWithType(left, right);
}
else if (auto ut = get<UnionType>(right))
return intersectUnionWithType(right, left);
if (auto it = get<IntersectionType>(left))
return intersectIntersectionWithType(left, right);
else if (auto it = get<IntersectionType>(right))
return intersectIntersectionWithType(right, left);
if (get<NegationType>(left))
{
if (get<NegationType>(right))
return intersectNegations(left, right);
else
return intersectTypeWithNegation(left, right);
}
else if (get<NegationType>(right))
return intersectTypeWithNegation(right, left);
std::optional<TypeId> res = basicIntersect(left, right);
if (res)
return *res;
else
return arena->addType(IntersectionType{{left, right}});
}
TypeId TypeSimplifier::union_(TypeId left, TypeId right)
{
RecursionLimiter rl(&recursionDepth, 15);
left = simplify(left);
right = simplify(right);
if (get<NeverType>(left))
return right;
if (get<NeverType>(right))
return left;
if (auto leftUnion = get<UnionType>(left))
{
bool changed = false;
std::set<TypeId> newParts;
for (TypeId part : leftUnion)
{
if (get<NeverType>(part))
{
changed = true;
continue;
}
Relation r = relate(part, right);
switch (r)
{
case Relation::Coincident:
case Relation::Superset:
return left;
default:
newParts.insert(part);
newParts.insert(right);
changed = true;
break;
}
}
if (!changed)
return left;
if (1 == newParts.size())
return *begin(newParts);
return arena->addType(UnionType{std::vector<TypeId>{begin(newParts), end(newParts)}});
}
else if (get<UnionType>(right))
return union_(right, left);
Relation r = relate(left, right);
if (left == right || r == Relation::Coincident || r == Relation::Superset)
return left;
if (r == Relation::Subset)
return right;
if (auto as = get<SingletonType>(left))
{
if (auto abs = as->variant.get_if<BooleanSingleton>())
{
if (auto bs = get<SingletonType>(right))
{
if (auto bbs = bs->variant.get_if<BooleanSingleton>())
{
if (abs->value != bbs->value)
return builtinTypes->booleanType;
}
}
}
}
return arena->addType(UnionType{{left, right}});
}
TypeId TypeSimplifier::simplify(TypeId ty)
{
DenseHashSet<TypeId> seen{nullptr};
return simplify(ty, seen);
}
TypeId TypeSimplifier::simplify(TypeId ty, DenseHashSet<TypeId>& seen)
{
RecursionLimiter limiter(&recursionDepth, 60);
ty = follow(ty);
if (seen.find(ty))
return ty;
seen.insert(ty);
if (auto nt = get<NegationType>(ty))
{
TypeId negatedTy = follow(nt->ty);
if (get<AnyType>(negatedTy))
return builtinTypes->neverType;
else if (get<NeverType>(negatedTy))
return builtinTypes->anyType;
if (auto nnt = get<NegationType>(negatedTy))
return simplify(nnt->ty, seen);
}
// Promote {x: never} to never
if (auto tt = get<TableType>(ty))
{
if (1 == tt->props.size())
{
TypeId propTy = simplify(begin(tt->props)->second.type(), seen);
if (get<NeverType>(propTy))
return builtinTypes->neverType;
}
}
return ty;
}
SimplifyResult simplifyIntersection(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, TypeId left, TypeId right)
{
LUAU_ASSERT(FFlag::DebugLuauDeferredConstraintResolution);
TypeSimplifier s{builtinTypes, arena};
// fprintf(stderr, "Intersect %s and %s ...\n", toString(left).c_str(), toString(right).c_str());
TypeId res = s.intersect(left, right);
// fprintf(stderr, "Intersect %s and %s -> %s\n", toString(left).c_str(), toString(right).c_str(), toString(res).c_str());
return SimplifyResult{res, std::move(s.blockedTypes)};
}
SimplifyResult simplifyUnion(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, TypeId left, TypeId right)
{
LUAU_ASSERT(FFlag::DebugLuauDeferredConstraintResolution);
TypeSimplifier s{builtinTypes, arena};
TypeId res = s.union_(left, right);
// fprintf(stderr, "Union %s and %s -> %s\n", toString(left).c_str(), toString(right).c_str(), toString(res).c_str());
return SimplifyResult{res, std::move(s.blockedTypes)};
}
} // namespace Luau
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