luau/tests/TypeInfer.aliases.test.cpp

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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 "Fixture.h"
#include "doctest.h"
#include "Luau/BuiltinDefinitions.h"
using namespace Luau;
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LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
LUAU_FASTFLAG(LuauNoMoreGlobalSingletonTypes)
LUAU_FASTFLAG(LuauTypeMismatchInvarianceInError)
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TEST_SUITE_BEGIN("TypeAliases");
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TEST_CASE_FIXTURE(Fixture, "basic_alias")
{
CheckResult result = check(R"(
type T = number
local x: T = 1
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK_EQ("number", toString(requireType("x")));
}
TEST_CASE_FIXTURE(Fixture, "cyclic_function_type_in_type_alias")
{
CheckResult result = check(R"(
type F = () -> F?
local function f()
return f
end
local g: F = f
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK_EQ("t1 where t1 = () -> t1?", toString(requireType("g")));
}
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TEST_CASE_FIXTURE(Fixture, "names_are_ascribed")
{
CheckResult result = check(R"(
type T = { x: number }
local x: T
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK_EQ("T", toString(requireType("x")));
}
TEST_CASE_FIXTURE(Fixture, "cannot_steal_hoisted_type_alias")
{
// This is a tricky case. In order to support recursive type aliases,
// we first walk the block and generate free types as placeholders.
// We then walk the AST as normal. If we declare a type alias as below,
// we generate a free type. We then begin our normal walk, examining
// local x: T = "foo", which establishes two constraints:
// a <: b
// string <: a
// We then visit the type alias, and establish that
// b <: number
// Then, when solving these constraints, we dispatch them in the order
// they appear above. This means that a ~ b, and a ~ string, thus
// b ~ string. This means the b <: number constraint has no effect.
// Essentially we've "stolen" the alias's type out from under it.
// This test ensures that we don't actually do this.
CheckResult result = check(R"(
local x: T = "foo"
type T = number
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
if (FFlag::DebugLuauDeferredConstraintResolution)
{
CHECK(result.errors[0] == TypeError{
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Location{{1, 21}, {1, 26}},
getMainSourceModule()->name,
TypeMismatch{
singletonTypes->numberType,
singletonTypes->stringType,
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},
});
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}
else
{
CHECK(result.errors[0] == TypeError{
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Location{{1, 8}, {1, 26}},
getMainSourceModule()->name,
TypeMismatch{
singletonTypes->numberType,
singletonTypes->stringType,
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},
});
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}
}
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TEST_CASE_FIXTURE(Fixture, "mismatched_generic_type_param")
{
CheckResult result = check(R"(
type T<A> = (A...) -> ()
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
CHECK(toString(result.errors[0]) ==
"Generic type 'A' is used as a variadic type parameter; consider changing 'A' to 'A...' in the generic argument list");
CHECK(result.errors[0].location == Location{{1, 21}, {1, 25}});
}
TEST_CASE_FIXTURE(Fixture, "mismatched_generic_pack_type_param")
{
CheckResult result = check(R"(
type T<A...> = (A) -> ()
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
CHECK(toString(result.errors[0]) ==
"Variadic type parameter 'A...' is used as a regular generic type; consider changing 'A...' to 'A' in the generic argument list");
CHECK(result.errors[0].location == Location{{1, 24}, {1, 25}});
}
TEST_CASE_FIXTURE(Fixture, "default_type_parameter")
{
CheckResult result = check(R"(
type T<A = number, B = string> = { a: A, b: B }
local x: T<string> = { a = "foo", b = "bar" }
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK(toString(requireType("x")) == "T<string, string>");
}
TEST_CASE_FIXTURE(Fixture, "default_pack_parameter")
{
CheckResult result = check(R"(
type T<A... = (number, string)> = { fn: (A...) -> () }
local x: T
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK(toString(requireType("x")) == "T<number, string>");
}
TEST_CASE_FIXTURE(Fixture, "saturate_to_first_type_pack")
{
CheckResult result = check(R"(
type T<A, B, C...> = { fn: (A, B) -> C... }
local x: T<string, number, string, boolean>
local f = x.fn
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK(toString(requireType("x")) == "T<string, number, string, boolean>");
CHECK(toString(requireType("f")) == "(string, number) -> (string, boolean)");
}
TEST_CASE_FIXTURE(Fixture, "cyclic_types_of_named_table_fields_do_not_expand_when_stringified")
{
CheckResult result = check(R"(
--!strict
type Node = { Parent: Node?; }
local node: Node;
node.Parent = 1
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
REQUIRE(tm);
CHECK_EQ("Node?", toString(tm->wantedType));
CHECK_EQ(typeChecker.numberType, tm->givenType);
}
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TEST_CASE_FIXTURE(Fixture, "mutually_recursive_aliases")
{
CheckResult result = check(R"(
--!strict
type T = { f: number, g: U }
type U = { h: number, i: T? }
local x: T = { f = 37, g = { h = 5, i = nil } }
x.g.i = x
local y: T = { f = 3, g = { h = 5, i = nil } }
y.g.i = y
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
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TEST_CASE_FIXTURE(Fixture, "generic_aliases")
{
ScopedFastFlag sff_DebugLuauDeferredConstraintResolution{"DebugLuauDeferredConstraintResolution", true};
CheckResult result = check(R"(
type T<a> = { v: a }
local x: T<number> = { v = 123 }
local y: T<string> = { v = "foo" }
local bad: T<number> = { v = "foo" }
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
const char* expectedError;
if (FFlag::LuauTypeMismatchInvarianceInError)
expectedError = "Type '{ v: string }' could not be converted into 'T<number>'\n"
"caused by:\n"
" Property 'v' is not compatible. Type 'string' could not be converted into 'number' in an invariant context";
else
expectedError = "Type '{ v: string }' could not be converted into 'T<number>'\n"
"caused by:\n"
" Property 'v' is not compatible. Type 'string' could not be converted into 'number'";
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CHECK(result.errors[0].location == Location{{4, 31}, {4, 44}});
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CHECK(toString(result.errors[0]) == expectedError);
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}
TEST_CASE_FIXTURE(Fixture, "dependent_generic_aliases")
{
ScopedFastFlag sff_DebugLuauDeferredConstraintResolution{"DebugLuauDeferredConstraintResolution", true};
CheckResult result = check(R"(
type T<a> = { v: a }
type U<a> = { t: T<a> }
local x: U<number> = { t = { v = 123 } }
local bad: U<number> = { t = { v = "foo" } }
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
const char* expectedError;
if (FFlag::LuauTypeMismatchInvarianceInError)
expectedError = "Type '{ t: { v: string } }' could not be converted into 'U<number>'\n"
"caused by:\n"
" Property 't' is not compatible. Type '{ v: string }' could not be converted into 'T<number>'\n"
"caused by:\n"
" Property 'v' is not compatible. Type 'string' could not be converted into 'number' in an invariant context";
else
expectedError = "Type '{ t: { v: string } }' could not be converted into 'U<number>'\n"
"caused by:\n"
" Property 't' is not compatible. Type '{ v: string }' could not be converted into 'T<number>'\n"
"caused by:\n"
" Property 'v' is not compatible. Type 'string' could not be converted into 'number'";
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CHECK(result.errors[0].location == Location{{4, 31}, {4, 52}});
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CHECK(toString(result.errors[0]) == expectedError);
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}
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TEST_CASE_FIXTURE(Fixture, "mutually_recursive_generic_aliases")
{
CheckResult result = check(R"(
--!strict
type T<a> = { f: a, g: U<a> }
type U<a> = { h: a, i: T<a>? }
local x: T<number> = { f = 37, g = { h = 5, i = nil } }
x.g.i = x
local y: T<string> = { f = "hi", g = { h = "lo", i = nil } }
y.g.i = y
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "mutually_recursive_types_errors")
{
CheckResult result = check(R"(
--!strict
type T<a> = { f: a, g: U<a> }
type U<b> = { h: b, i: T<b>? }
local x: T<number> = { f = 37, g = { h = 5, i = nil } }
x.g.i = x
local y: T<string> = { f = "hi", g = { h = 5, i = nil } }
y.g.i = y
)");
LUAU_REQUIRE_ERRORS(result);
// We had a UAF in this example caused by not cloning type function arguments
ModulePtr module = frontend.moduleResolver.getModule("MainModule");
unfreeze(module->interfaceTypes);
copyErrors(module->errors, module->interfaceTypes);
freeze(module->interfaceTypes);
module->internalTypes.clear();
module->astTypes.clear();
// Make sure the error strings don't include "VALUELESS"
for (auto error : module->errors)
CHECK_MESSAGE(toString(error).find("VALUELESS") == std::string::npos, toString(error));
}
TEST_CASE_FIXTURE(Fixture, "use_table_name_and_generic_params_in_errors")
{
CheckResult result = check(R"(
type Pair<T, U> = {first: T, second: U}
local a: Pair<string, number>
local b: Pair<string, string>
a = b
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
REQUIRE(tm);
CHECK_EQ("Pair<string, number>", toString(tm->wantedType));
CHECK_EQ("Pair<string, string>", toString(tm->givenType));
}
TEST_CASE_FIXTURE(Fixture, "dont_stop_typechecking_after_reporting_duplicate_type_definition")
{
CheckResult result = check(R"(
type A = number
type A = string -- Redefinition of type 'A', previously defined at line 1
local foo: string = 1 -- "Type 'number' could not be converted into 'string'"
)");
LUAU_REQUIRE_ERROR_COUNT(2, result);
}
TEST_CASE_FIXTURE(Fixture, "stringify_type_alias_of_recursive_template_table_type")
{
CheckResult result = check(R"(
type Table<T> = { a: T }
type Wrapped = Table<Wrapped>
local l: Wrapped = 2
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
REQUIRE(tm);
CHECK_EQ("Wrapped", toString(tm->wantedType));
CHECK_EQ(typeChecker.numberType, tm->givenType);
}
TEST_CASE_FIXTURE(Fixture, "stringify_type_alias_of_recursive_template_table_type2")
{
CheckResult result = check(R"(
type Table<T> = { a: T }
type Wrapped = (Table<Wrapped>) -> string
local l: Wrapped = 2
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
REQUIRE(tm);
CHECK_EQ("t1 where t1 = ({| a: t1 |}) -> string", toString(tm->wantedType));
CHECK_EQ(typeChecker.numberType, tm->givenType);
}
// Check that recursive intersection type doesn't generate an OOM
TEST_CASE_FIXTURE(Fixture, "cli_38393_recursive_intersection_oom")
{
CheckResult result = check(R"(
function _(l0:(t0)&((t0)&(((t0)&((t0)->()))->(typeof(_),typeof(# _)))),l39,...):any
end
type t0<t0> = ((typeof(_))&((t0)&(((typeof(_))&(t0))->typeof(_))),{n163:any,})->(any,typeof(_))
_(_)
)");
LUAU_REQUIRE_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "type_alias_fwd_declaration_is_precise")
{
CheckResult result = check(R"(
local foo: Id<number> = 1
type Id<T> = T
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "corecursive_types_generic")
{
const std::string code = R"(
type A<T> = {v:T, b:B<T>}
type B<T> = {v:T, a:A<T>}
local aa:A<number>
local bb = aa
)";
const std::string expected = R"(
type A<T> = {v:T, b:B<T>}
type B<T> = {v:T, a:A<T>}
local aa:A<number>
local bb:A<number>=aa
)";
CHECK_EQ(expected, decorateWithTypes(code));
CheckResult result = check(code);
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "corecursive_function_types")
{
CheckResult result = check(R"(
type A = () -> (number, B)
type B = () -> (string, A)
local a: A
local b: B
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK_EQ("t1 where t1 = () -> (number, () -> (string, t1))", toString(requireType("a")));
CHECK_EQ("t1 where t1 = () -> (string, () -> (number, t1))", toString(requireType("b")));
}
TEST_CASE_FIXTURE(Fixture, "generic_param_remap")
{
const std::string code = R"(
-- An example of a forwarded use of a type that has different type arguments than parameters
type A<T,U> = {t:T, u:U, next:A<U,T>?}
local aa:A<number,string> = { t = 5, u = 'hi', next = { t = 'lo', u = 8 } }
local bb = aa
)";
const std::string expected = R"(
type A<T,U> = {t:T, u:U, next:A<U,T>?}
local aa:A<number,string> = { t = 5, u = 'hi', next = { t = 'lo', u = 8 } }
local bb:A<number,string>=aa
)";
CHECK_EQ(expected, decorateWithTypes(code));
CheckResult result = check(code);
LUAU_REQUIRE_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "export_type_and_type_alias_are_duplicates")
{
CheckResult result = check(R"(
export type Foo = number
type Foo = number
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
auto dtd = get<DuplicateTypeDefinition>(result.errors[0]);
REQUIRE(dtd);
CHECK_EQ(dtd->name, "Foo");
}
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TEST_CASE_FIXTURE(Fixture, "reported_location_is_correct_when_type_alias_are_duplicates")
{
CheckResult result = check(R"(
type A = string
type B = number
type C = string
type B = number
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
auto dtd = get<DuplicateTypeDefinition>(result.errors[0]);
REQUIRE(dtd);
CHECK_EQ(dtd->name, "B");
REQUIRE(dtd->previousLocation);
CHECK_EQ(dtd->previousLocation->begin.line + 1, 3);
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}
TEST_CASE_FIXTURE(Fixture, "stringify_optional_parameterized_alias")
{
CheckResult result = check(R"(
type Node<T> = { value: T, child: Node<T>? }
local function visitor<T>(node: Node<T>?)
local a: Node<T>
if node then
a = node.child -- Observe the output of the error message.
end
end
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
auto e = get<TypeMismatch>(result.errors[0]);
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REQUIRE(e != nullptr);
CHECK_EQ("Node<T>?", toString(e->givenType));
CHECK_EQ("Node<T>", toString(e->wantedType));
}
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TEST_CASE_FIXTURE(BuiltinsFixture, "general_require_multi_assign")
{
fileResolver.source["workspace/A"] = R"(
export type myvec2 = {x: number, y: number}
return {}
)";
fileResolver.source["workspace/B"] = R"(
export type myvec3 = {x: number, y: number, z: number}
return {}
)";
fileResolver.source["workspace/C"] = R"(
local Foo, Bar = require(workspace.A), require(workspace.B)
local a: Foo.myvec2
local b: Bar.myvec3
)";
CheckResult result = frontend.check("workspace/C");
LUAU_REQUIRE_NO_ERRORS(result);
ModulePtr m = frontend.moduleResolver.modules["workspace/C"];
REQUIRE(m != nullptr);
std::optional<TypeId> aTypeId = lookupName(m->getModuleScope(), "a");
REQUIRE(aTypeId);
const Luau::TableTypeVar* aType = get<TableTypeVar>(follow(*aTypeId));
REQUIRE(aType);
REQUIRE(aType->props.size() == 2);
std::optional<TypeId> bTypeId = lookupName(m->getModuleScope(), "b");
REQUIRE(bTypeId);
const Luau::TableTypeVar* bType = get<TableTypeVar>(follow(*bTypeId));
REQUIRE(bType);
REQUIRE(bType->props.size() == 3);
}
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TEST_CASE_FIXTURE(BuiltinsFixture, "type_alias_import_mutation")
{
ScopedFastFlag luauNewLibraryTypeNames{"LuauNewLibraryTypeNames", true};
CheckResult result = check("type t10<x> = typeof(table)");
LUAU_REQUIRE_NO_ERRORS(result);
TypeId ty = getGlobalBinding(frontend, "table");
if (FFlag::LuauNoMoreGlobalSingletonTypes)
{
CHECK_EQ(toString(ty), "typeof(table)");
}
else
{
CHECK_EQ(toString(ty), "table");
}
const TableTypeVar* ttv = get<TableTypeVar>(ty);
REQUIRE(ttv);
CHECK(ttv->instantiatedTypeParams.empty());
}
TEST_CASE_FIXTURE(Fixture, "type_alias_local_mutation")
{
CheckResult result = check(R"(
type Cool = { a: number, b: string }
local c: Cool = { a = 1, b = "s" }
type NotCool<x> = Cool
)");
LUAU_REQUIRE_NO_ERRORS(result);
std::optional<TypeId> ty = requireType("c");
REQUIRE(ty);
CHECK_EQ(toString(*ty), "Cool");
const TableTypeVar* ttv = get<TableTypeVar>(*ty);
REQUIRE(ttv);
CHECK(ttv->instantiatedTypeParams.empty());
}
TEST_CASE_FIXTURE(Fixture, "type_alias_local_rename")
{
CheckResult result = check(R"(
type Cool = { a: number, b: string }
type NotCool = Cool
local c: Cool = { a = 1, b = "s" }
local d: NotCool = { a = 1, b = "s" }
)");
LUAU_REQUIRE_NO_ERRORS(result);
std::optional<TypeId> ty = requireType("c");
REQUIRE(ty);
CHECK_EQ(toString(*ty), "Cool");
ty = requireType("d");
REQUIRE(ty);
CHECK_EQ(toString(*ty), "NotCool");
}
TEST_CASE_FIXTURE(Fixture, "type_alias_local_synthetic_mutation")
{
CheckResult result = check(R"(
local c = { a = 1, b = "s" }
type Cool = typeof(c)
)");
LUAU_REQUIRE_NO_ERRORS(result);
std::optional<TypeId> ty = requireType("c");
REQUIRE(ty);
const TableTypeVar* ttv = get<TableTypeVar>(*ty);
REQUIRE(ttv);
CHECK_EQ(ttv->name, "Cool");
}
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TEST_CASE_FIXTURE(BuiltinsFixture, "type_alias_of_an_imported_recursive_type")
{
fileResolver.source["game/A"] = R"(
export type X = { a: number, b: X? }
return {}
)";
CheckResult aResult = frontend.check("game/A");
LUAU_REQUIRE_NO_ERRORS(aResult);
CheckResult bResult = check(R"(
local Import = require(game.A)
type X = Import.X
)");
LUAU_REQUIRE_NO_ERRORS(bResult);
std::optional<TypeId> ty1 = lookupImportedType("Import", "X");
REQUIRE(ty1);
std::optional<TypeId> ty2 = lookupType("X");
REQUIRE(ty2);
CHECK_EQ(follow(*ty1), follow(*ty2));
}
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TEST_CASE_FIXTURE(BuiltinsFixture, "type_alias_of_an_imported_recursive_generic_type")
{
fileResolver.source["game/A"] = R"(
export type X<T, U> = { a: T, b: U, C: X<T, U>? }
return {}
)";
CheckResult aResult = frontend.check("game/A");
LUAU_REQUIRE_NO_ERRORS(aResult);
CheckResult bResult = check(R"(
local Import = require(game.A)
type X<T, U> = Import.X<T, U>
)");
LUAU_REQUIRE_NO_ERRORS(bResult);
std::optional<TypeId> ty1 = lookupImportedType("Import", "X");
REQUIRE(ty1);
std::optional<TypeId> ty2 = lookupType("X");
REQUIRE(ty2);
CHECK_EQ(toString(*ty1, {true}), toString(*ty2, {true}));
bResult = check(R"(
local Import = require(game.A)
type X<T, U> = Import.X<U, T>
)");
LUAU_REQUIRE_NO_ERRORS(bResult);
ty1 = lookupImportedType("Import", "X");
REQUIRE(ty1);
ty2 = lookupType("X");
REQUIRE(ty2);
CHECK_EQ(toString(*ty1, {true}), "t1 where t1 = {| C: t1?, a: T, b: U |}");
CHECK_EQ(toString(*ty2, {true}), "{| C: t1, a: U, b: T |} where t1 = {| C: t1, a: U, b: T |}?");
}
TEST_CASE_FIXTURE(Fixture, "module_export_free_type_leak")
{
CheckResult result = check(R"(
function get()
return function(obj) return true end
end
export type f = typeof(get())
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "module_export_wrapped_free_type_leak")
{
CheckResult result = check(R"(
function get()
return {a = 1, b = function(obj) return true end}
end
export type f = typeof(get())
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "mutually_recursive_types_restriction_ok")
{
CheckResult result = check(R"(
type Tree<T> = { data: T, children: Forest<T> }
type Forest<T> = {Tree<T>}
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "mutually_recursive_types_restriction_not_ok_1")
{
CheckResult result = check(R"(
-- OK because forwarded types are used with their parameters.
type Tree<T> = { data: T, children: Forest<T> }
type Forest<T> = {Tree<{T}>}
)");
LUAU_REQUIRE_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "mutually_recursive_types_restriction_not_ok_2")
{
CheckResult result = check(R"(
-- Not OK because forwarded types are used with different types than their parameters.
type Forest<T> = {Tree<{T}>}
type Tree<T> = { data: T, children: Forest<T> }
)");
LUAU_REQUIRE_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "mutually_recursive_types_swapsies_ok")
{
CheckResult result = check(R"(
type Tree1<T,U> = { data: T, children: {Tree2<U,T>} }
type Tree2<U,T> = { data: U, children: {Tree1<T,U>} }
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "mutually_recursive_types_swapsies_not_ok")
{
CheckResult result = check(R"(
type Tree1<T,U> = { data: T, children: {Tree2<U,T>} }
type Tree2<T,U> = { data: U, children: {Tree1<T,U>} }
)");
LUAU_REQUIRE_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "free_variables_from_typeof_in_aliases")
{
CheckResult result = check(R"(
function f(x) return x[1] end
-- x has type X? for a free type variable X
local x = f ({})
type ContainsFree<a> = { this: a, that: typeof(x) }
type ContainsContainsFree = { that: ContainsFree<number> }
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "non_recursive_aliases_that_reuse_a_generic_name")
{
CheckResult result = check(R"(
type Array<T> = { [number]: T }
type Tuple<T, V> = Array<T | V>
local p: Tuple<number, string>
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK_EQ("{number | string}", toString(requireType("p"), {true}));
}
/*
* We had a problem where all type aliases would be prototyped into a child scope that happened
* to have the same level. This caused a problem where, if a sibling function referred to that
* type alias in its type signature, it would erroneously be quantified away, even though it doesn't
* actually belong to the function.
*
* We solved this by ascribing a unique subLevel to each prototyped alias.
*/
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TEST_CASE_FIXTURE(BuiltinsFixture, "do_not_quantify_unresolved_aliases")
{
CheckResult result = check(R"(
--!strict
local KeyPool = {}
local function newkey(pool: KeyPool, index)
return {}
end
function newKeyPool()
local pool = {
available = {} :: {Key},
}
return setmetatable(pool, KeyPool)
end
export type KeyPool = typeof(newKeyPool())
export type Key = typeof(newkey(newKeyPool(), 1))
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
/*
* We keep a cache of type alias onto TypeVar to prevent infinite types from
* being constructed via recursive or corecursive aliases. We have to adjust
* the TypeLevels of those generic TypeVars so that the unifier doesn't think
* they have improperly leaked out of their scope.
*/
TEST_CASE_FIXTURE(Fixture, "generic_typevars_are_not_considered_to_escape_their_scope_if_they_are_reused_in_multiple_aliases")
{
CheckResult result = check(R"(
type Array<T> = {T}
type Exclude<T, V> = T
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
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/*
* The two-pass alias definition system starts by ascribing a free TypeVar to each alias. It then
* circles back to fill in the actual type later on.
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*
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* If this free type is unified with something degenerate like `any`, we need to take extra care
* to ensure that the alias actually binds to the type that the user expected.
*/
TEST_CASE_FIXTURE(Fixture, "forward_declared_alias_is_not_clobbered_by_prior_unification_with_any")
{
CheckResult result = check(R"(
local function x()
local y: FutureType = {}::any
return 1
end
type FutureType = { foo: typeof(x()) }
local d: FutureType = { smth = true } -- missing error, 'd' is resolved to 'any'
)");
CHECK_EQ("{| foo: number |}", toString(requireType("d"), {true}));
LUAU_REQUIRE_ERROR_COUNT(1, result);
}
TEST_CASE_FIXTURE(Fixture, "forward_declared_alias_is_not_clobbered_by_prior_unification_with_any_2")
{
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ScopedFastFlag sff[] = {
{"DebugLuauSharedSelf", true},
};
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CheckResult result = check(R"(
local B = {}
B.bar = 4
function B:smth1()
local self: FutureIntersection = self
self.foo = 4
return 4
end
function B:smth2()
local self: FutureIntersection = self
self.bar = 5 -- error, even though we should have B part with bar
end
type A = { foo: typeof(B.smth1({foo=3})) } -- trick toposort into sorting functions before types
type B = typeof(B)
type FutureIntersection = A & B
)");
if (FFlag::DebugLuauDeferredConstraintResolution)
{
// To be quite honest, I don't know exactly why DCR fixes this.
LUAU_REQUIRE_NO_ERRORS(result);
}
else
{
// TODO: shared self causes this test to break in bizarre ways.
LUAU_REQUIRE_ERRORS(result);
}
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}
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TEST_CASE_FIXTURE(Fixture, "recursive_types_restriction_ok")
{
CheckResult result = check(R"(
type Tree<T> = { data: T, children: {Tree<T>} }
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "recursive_types_restriction_not_ok")
{
CheckResult result = check(R"(
-- this would be an infinite type if we allowed it
type Tree<T> = { data: T, children: {Tree<{T}>} }
)");
LUAU_REQUIRE_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "report_shadowed_aliases")
{
ScopedFastFlag sff{"LuauReportShadowedTypeAlias", true};
// We allow a previous type alias to depend on a future type alias. That exact feature enables a confusing example, like the following snippet,
// which has the type alias FakeString point to the type alias `string` that which points to `number`.
CheckResult result = check(R"(
type MyString = string
type string = number
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
CHECK(toString(result.errors[0]) == "Redefinition of type 'string'");
std::optional<TypeId> t1 = lookupType("MyString");
REQUIRE(t1);
CHECK(isPrim(*t1, PrimitiveTypeVar::String));
std::optional<TypeId> t2 = lookupType("string");
REQUIRE(t2);
CHECK(isPrim(*t2, PrimitiveTypeVar::String));
}
TEST_CASE_FIXTURE(Fixture, "it_is_ok_to_shadow_user_defined_alias")
{
CheckResult result = check(R"(
type T = number
do
type T = string
end
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "cannot_create_cyclic_type_with_unknown_module")
{
CheckResult result = check(R"(
type AAA = B.AAA
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
CHECK(toString(result.errors[0]) == "Unknown type 'B.AAA'");
}
TEST_SUITE_END();