luau/tests/TypeInfer.tryUnify.test.cpp

// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
#include "Luau/Scope.h"
#include "Luau/TypeInfer.h"
#include "Luau/TypeVar.h"

#include "Fixture.h"

#include "doctest.h"

using namespace Luau;

struct TryUnifyFixture : Fixture
{
    TypeArena arena;
    ScopePtr globalScope{new Scope{arena.addTypePack({TypeId{}})}};
    InternalErrorReporter iceHandler;
    UnifierSharedState unifierState{&iceHandler};
    Normalizer normalizer{&arena, singletonTypes, NotNull{&unifierState}};
    Unifier state{NotNull{&normalizer}, Mode::Strict, NotNull{globalScope.get()}, Location{}, Variance::Covariant};
};

TEST_SUITE_BEGIN("TryUnifyTests");

TEST_CASE_FIXTURE(TryUnifyFixture, "primitives_unify")
{
    TypeVar numberOne{TypeVariant{PrimitiveTypeVar{PrimitiveTypeVar::Number}}};
    TypeVar numberTwo = numberOne;

    state.tryUnify(&numberTwo, &numberOne);

    CHECK(state.errors.empty());
}

TEST_CASE_FIXTURE(TryUnifyFixture, "compatible_functions_are_unified")
{
    TypeVar functionOne{
        TypeVariant{FunctionTypeVar(arena.addTypePack({arena.freshType(globalScope->level)}), arena.addTypePack({typeChecker.numberType}))}};

    TypeVar functionTwo{TypeVariant{
        FunctionTypeVar(arena.addTypePack({arena.freshType(globalScope->level)}), arena.addTypePack({arena.freshType(globalScope->level)}))}};

    state.tryUnify(&functionTwo, &functionOne);
    CHECK(state.errors.empty());

    state.log.commit();

    CHECK_EQ(functionOne, functionTwo);
}

TEST_CASE_FIXTURE(TryUnifyFixture, "incompatible_functions_are_preserved")
{
    TypePackVar argPackOne{TypePack{{arena.freshType(globalScope->level)}, std::nullopt}};
    TypeVar functionOne{
        TypeVariant{FunctionTypeVar(arena.addTypePack({arena.freshType(globalScope->level)}), arena.addTypePack({typeChecker.numberType}))}};

    TypeVar functionOneSaved = functionOne;

    TypePackVar argPackTwo{TypePack{{arena.freshType(globalScope->level)}, std::nullopt}};
    TypeVar functionTwo{
        TypeVariant{FunctionTypeVar(arena.addTypePack({arena.freshType(globalScope->level)}), arena.addTypePack({typeChecker.stringType}))}};

    TypeVar functionTwoSaved = functionTwo;

    state.tryUnify(&functionTwo, &functionOne);
    CHECK(!state.errors.empty());

    CHECK_EQ(functionOne, functionOneSaved);
    CHECK_EQ(functionTwo, functionTwoSaved);
}

TEST_CASE_FIXTURE(TryUnifyFixture, "tables_can_be_unified")
{
    TypeVar tableOne{TypeVariant{
        TableTypeVar{{{"foo", {arena.freshType(globalScope->level)}}}, std::nullopt, globalScope->level, TableState::Unsealed},
    }};

    TypeVar tableTwo{TypeVariant{
        TableTypeVar{{{"foo", {arena.freshType(globalScope->level)}}}, std::nullopt, globalScope->level, TableState::Unsealed},
    }};

    CHECK_NE(*getMutable<TableTypeVar>(&tableOne)->props["foo"].type, *getMutable<TableTypeVar>(&tableTwo)->props["foo"].type);

    state.tryUnify(&tableTwo, &tableOne);

    CHECK(state.errors.empty());

    state.log.commit();

    CHECK_EQ(*getMutable<TableTypeVar>(&tableOne)->props["foo"].type, *getMutable<TableTypeVar>(&tableTwo)->props["foo"].type);
}

TEST_CASE_FIXTURE(TryUnifyFixture, "incompatible_tables_are_preserved")
{
    TypeVar tableOne{TypeVariant{
        TableTypeVar{{{"foo", {arena.freshType(globalScope->level)}}, {"bar", {typeChecker.numberType}}}, std::nullopt, globalScope->level,
            TableState::Unsealed},
    }};

    TypeVar tableTwo{TypeVariant{
        TableTypeVar{{{"foo", {arena.freshType(globalScope->level)}}, {"bar", {typeChecker.stringType}}}, std::nullopt, globalScope->level,
            TableState::Unsealed},
    }};

    CHECK_NE(*getMutable<TableTypeVar>(&tableOne)->props["foo"].type, *getMutable<TableTypeVar>(&tableTwo)->props["foo"].type);

    state.tryUnify(&tableTwo, &tableOne);

    CHECK_EQ(1, state.errors.size());

    CHECK_NE(*getMutable<TableTypeVar>(&tableOne)->props["foo"].type, *getMutable<TableTypeVar>(&tableTwo)->props["foo"].type);
}

TEST_CASE_FIXTURE(TryUnifyFixture, "members_of_failed_typepack_unification_are_unified_with_errorType")
{
    CheckResult result = check(R"(
        function f(arg: number) end
        local a
        local b
        f(a, b)
    )");

    LUAU_REQUIRE_ERROR_COUNT(1, result);

    CHECK_EQ("a", toString(requireType("a")));
    CHECK_EQ("*error-type*", toString(requireType("b")));
}

TEST_CASE_FIXTURE(TryUnifyFixture, "result_of_failed_typepack_unification_is_constrained")
{
    CheckResult result = check(R"(
        function f(arg: number) return arg end
        local a
        local b
        local c = f(a, b)
    )");

    LUAU_REQUIRE_ERROR_COUNT(1, result);

    CHECK_EQ("a", toString(requireType("a")));
    CHECK_EQ("*error-type*", toString(requireType("b")));
    CHECK_EQ("number", toString(requireType("c")));
}

TEST_CASE_FIXTURE(TryUnifyFixture, "typepack_unification_should_trim_free_tails")
{
    CheckResult result = check(R"(
        --!strict
        local function f(v: number)
            if v % 2 == 0 then
                return true
            end
        end

        return function()
            return (f(1))
        end
    )");

    LUAU_REQUIRE_ERROR_COUNT(1, result);
    CHECK_EQ("(number) -> boolean", toString(requireType("f")));
}

TEST_CASE_FIXTURE(TryUnifyFixture, "variadic_type_pack_unification")
{
    TypePackVar testPack{TypePack{{typeChecker.numberType, typeChecker.stringType}, std::nullopt}};
    TypePackVar variadicPack{VariadicTypePack{typeChecker.numberType}};

    state.tryUnify(&testPack, &variadicPack);
    CHECK(!state.errors.empty());
}

TEST_CASE_FIXTURE(TryUnifyFixture, "variadic_tails_respect_progress")
{
    TypePackVar variadicPack{VariadicTypePack{typeChecker.booleanType}};
    TypePackVar a{TypePack{{typeChecker.numberType, typeChecker.stringType, typeChecker.booleanType, typeChecker.booleanType}}};
    TypePackVar b{TypePack{{typeChecker.numberType, typeChecker.stringType}, &variadicPack}};

    state.tryUnify(&b, &a);
    CHECK(state.errors.empty());
}

TEST_CASE_FIXTURE(TryUnifyFixture, "variadics_should_use_reversed_properly")
{
    CheckResult result = check(R"(
        --!strict
        local function f<T>(...: T): ...T
            return ...
        end

        local x: string = f(1)
    )");

    LUAU_REQUIRE_ERROR_COUNT(1, result);
    TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
    REQUIRE(tm);
    CHECK_EQ(toString(tm->givenType), "number");
    CHECK_EQ(toString(tm->wantedType), "string");
}

TEST_CASE_FIXTURE(BuiltinsFixture, "cli_41095_concat_log_in_sealed_table_unification")
{
    CheckResult result = check(R"(
        --!strict
        table.insert()
    )");

    LUAU_REQUIRE_ERROR_COUNT(2, result);
    CHECK_EQ(toString(result.errors[0]), "No overload for function accepts 0 arguments.");
    CHECK_EQ(toString(result.errors[1]), "Available overloads: ({a}, a) -> (); and ({a}, number, a) -> ()");
}

TEST_CASE_FIXTURE(TryUnifyFixture, "free_tail_is_grown_properly")
{
    TypePackId threeNumbers = arena.addTypePack(TypePack{{typeChecker.numberType, typeChecker.numberType, typeChecker.numberType}, std::nullopt});
    TypePackId numberAndFreeTail = arena.addTypePack(TypePack{{typeChecker.numberType}, arena.addTypePack(TypePackVar{FreeTypePack{TypeLevel{}}})});

    ErrorVec unifyErrors = state.canUnify(numberAndFreeTail, threeNumbers);
    CHECK(unifyErrors.size() == 0);
}

TEST_CASE_FIXTURE(TryUnifyFixture, "recursive_metatable_getmatchtag")
{
    TypeVar redirect{FreeTypeVar{TypeLevel{}}};
    TypeVar table{TableTypeVar{}};
    TypeVar metatable{MetatableTypeVar{&redirect, &table}};
    redirect = BoundTypeVar{&metatable}; // Now we have a metatable that is recursive on the table type
    TypeVar variant{UnionTypeVar{{&metatable, typeChecker.numberType}}};

    state.tryUnify(&metatable, &variant);
}

TEST_CASE_FIXTURE(TryUnifyFixture, "cli_50320_follow_in_any_unification")
{
    TypePackVar free{FreeTypePack{TypeLevel{}}};
    TypePackVar target{TypePack{}};

    TypeVar func{FunctionTypeVar{&free, &free}};

    state.tryUnify(&free, &target);
    // Shouldn't assert or error.
    state.tryUnify(&func, typeChecker.anyType);
}

TEST_CASE_FIXTURE(TryUnifyFixture, "txnlog_preserves_type_owner")
{
    TypeId a = arena.addType(TypeVar{FreeTypeVar{TypeLevel{}}});
    TypeId b = typeChecker.numberType;

    state.tryUnify(a, b);
    state.log.commit();

    CHECK_EQ(a->owningArena, &arena);
}

TEST_CASE_FIXTURE(TryUnifyFixture, "txnlog_preserves_pack_owner")
{
    TypePackId a = arena.addTypePack(TypePackVar{FreeTypePack{TypeLevel{}}});
    TypePackId b = typeChecker.anyTypePack;

    state.tryUnify(a, b);
    state.log.commit();

    CHECK_EQ(a->owningArena, &arena);
}

TEST_CASE_FIXTURE(TryUnifyFixture, "metatables_unify_against_shape_of_free_table")
{
    ScopedFastFlag sff("DebugLuauDeferredConstraintResolution", true);

    TableTypeVar::Props freeProps{
        {"foo", {typeChecker.numberType}},
    };

    TypeId free = arena.addType(TableTypeVar{freeProps, std::nullopt, TypeLevel{}, TableState::Free});

    TableTypeVar::Props indexProps{
        {"foo", {typeChecker.stringType}},
    };

    TypeId index = arena.addType(TableTypeVar{indexProps, std::nullopt, TypeLevel{}, TableState::Sealed});

    TableTypeVar::Props mtProps{
        {"__index", {index}},
    };

    TypeId mt = arena.addType(TableTypeVar{mtProps, std::nullopt, TypeLevel{}, TableState::Sealed});

    TypeId target = arena.addType(TableTypeVar{TableState::Unsealed, TypeLevel{}});
    TypeId metatable = arena.addType(MetatableTypeVar{target, mt});

    state.tryUnify(metatable, free);
    state.log.commit();

    REQUIRE_EQ(state.errors.size(), 1);

    std::string expected = "Type '{ @metatable {| __index: {| foo: string |} |}, {  } }' could not be converted into '{- foo: number -}'\n"
                           "caused by:\n"
                           "  Type 'number' could not be converted into 'string'";
    CHECK_EQ(toString(state.errors[0]), expected);
}

TEST_SUITE_END();