luau/tests/TypeInfer.generics.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 "Luau/Parser.h"
#include "Luau/TypeInfer.h"
#include "Luau/TypeVar.h"
#include "Fixture.h"
#include "doctest.h"
using namespace Luau;
LUAU_FASTFLAG(LuauExtendedFunctionMismatchError)
TEST_SUITE_BEGIN("GenericsTests");
TEST_CASE_FIXTURE(Fixture, "check_generic_function")
{
CheckResult result = check(R"(
function id<a>(x:a): a
return x
end
local x: string = id("hi")
local y: number = id(37)
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "check_generic_local_function")
{
CheckResult result = check(R"(
local function id<a>(x:a): a
return x
end
local x: string = id("hi")
local y: number = id(37)
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "check_generic_typepack_function")
{
CheckResult result = check(R"(
function id<a...>(...: a...): (a...) return ... end
local x: string, y: boolean = id("hi", true)
local z: number = id(37)
id()
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "types_before_typepacks")
{
CheckResult result = check(R"(
function f<a,b...>() end
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "local_vars_can_be_polytypes")
{
CheckResult result = check(R"(
local function id<a>(x:a):a return x end
local f: <a>(a)->a = id
local x: string = f("hi")
local y: number = f(37)
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "inferred_local_vars_can_be_polytypes")
{
CheckResult result = check(R"(
local function id(x) return x end
print("This is bogus") -- TODO: CLI-39916
local f = id
local x: string = f("hi")
local y: number = f(37)
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "local_vars_can_be_instantiated_polytypes")
{
CheckResult result = check(R"(
local function id(x) return x end
print("This is bogus") -- TODO: CLI-39916
local f: (number)->number = id
local g: (string)->string = id
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "properties_can_be_polytypes")
{
CheckResult result = check(R"(
local t = {}
t.m = function<a>(x: a):a return x end
local x: string = t.m("hi")
local y: number = t.m(37)
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "properties_can_be_instantiated_polytypes")
{
CheckResult result = check(R"(
local t: { m: (number)->number } = { m = function(x:number) return x+1 end }
local function id<a>(x:a):a return x end
t.m = id
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "check_nested_generic_function")
{
CheckResult result = check(R"(
local function f()
local function id<a>(x:a): a
return x
end
local x: string = id("hi")
local y: number = id(37)
end
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "check_recursive_generic_function")
{
CheckResult result = check(R"(
local function id<a>(x:a):a
local y: string = id("hi")
local z: number = id(37)
return x
end
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "check_mutual_generic_functions")
{
CheckResult result = check(R"(
local id2
local function id1<a>(x:a):a
local y: string = id2("hi")
local z: number = id2(37)
return x
end
function id2<a>(x:a):a
local y: string = id1("hi")
local z: number = id1(37)
return x
end
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "generic_functions_in_types")
{
CheckResult result = check(R"(
type T = { id: <a>(a) -> a }
local x: T = { id = function<a>(x:a):a return x end }
local y: string = x.id("hi")
local z: number = x.id(37)
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "generic_factories")
{
CheckResult result = check(R"(
type T<a> = { id: (a) -> a }
type Factory = { build: <a>() -> T<a> }
local f: Factory = {
build = function<a>(): T<a>
return {
id = function(x:a):a
return x
end
}
end
}
local y: string = f.build().id("hi")
local z: number = f.build().id(37)
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "factories_of_generics")
{
CheckResult result = check(R"(
type T = { id: <a>(a) -> a }
type Factory = { build: () -> T }
local f: Factory = {
build = function(): T
return {
id = function<a>(x:a):a
return x
end
}
end
}
local x: T = f.build()
local y: string = x.id("hi")
local z: number = x.id(37)
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "infer_generic_function")
{
CheckResult result = check(R"(
function id(x)
return x
end
local x: string = id("hi")
local y: number = id(37)
)");
LUAU_REQUIRE_NO_ERRORS(result);
TypeId idType = requireType("id");
const FunctionTypeVar* idFun = get<FunctionTypeVar>(idType);
REQUIRE(idFun);
auto [args, varargs] = flatten(idFun->argTypes);
auto [rets, varrets] = flatten(idFun->retType);
CHECK_EQ(idFun->generics.size(), 1);
CHECK_EQ(idFun->genericPacks.size(), 0);
CHECK_EQ(args[0], idFun->generics[0]);
CHECK_EQ(rets[0], idFun->generics[0]);
}
TEST_CASE_FIXTURE(Fixture, "infer_generic_local_function")
{
CheckResult result = check(R"(
local function id(x)
return x
end
local x: string = id("hi")
local y: number = id(37)
)");
LUAU_REQUIRE_NO_ERRORS(result);
TypeId idType = requireType("id");
const FunctionTypeVar* idFun = get<FunctionTypeVar>(idType);
REQUIRE(idFun);
auto [args, varargs] = flatten(idFun->argTypes);
auto [rets, varrets] = flatten(idFun->retType);
CHECK_EQ(idFun->generics.size(), 1);
CHECK_EQ(idFun->genericPacks.size(), 0);
CHECK_EQ(args[0], idFun->generics[0]);
CHECK_EQ(rets[0], idFun->generics[0]);
}
TEST_CASE_FIXTURE(Fixture, "infer_nested_generic_function")
{
CheckResult result = check(R"(
local function f()
local function id(x)
return x
end
local x: string = id("hi")
local y: number = id(37)
end
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "infer_generic_methods")
{
CheckResult result = check(R"(
local x = {}
function x:id(x) return x end
function x:f(): string return self:id("hello") end
function x:g(): number return self:id(37) end
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "calling_self_generic_methods")
{
CheckResult result = check(R"(
local x = {}
function x:id(x) return x end
function x:f()
local x: string = self:id("hi")
local y: number = self:id(37)
end
)");
// TODO: Should typecheck but currently errors CLI-39916
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LUAU_REQUIRE_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "infer_generic_property")
{
CheckResult result = check(R"(
local t = {}
t.m = function(x) return x end
local x: string = t.m("hi")
local y: number = t.m(37)
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "function_arguments_can_be_polytypes")
{
CheckResult result = check(R"(
local function f(g: <a>(a)->a)
local x: number = g(37)
local y: string = g("hi")
end
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "function_results_can_be_polytypes")
{
CheckResult result = check(R"(
local function f() : <a>(a)->a
local function id<a>(x:a):a return x end
return id
end
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "type_parameters_can_be_polytypes")
{
CheckResult result = check(R"(
local function id<a>(x:a):a return x end
local f: <a>(a)->a = id(id)
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "dont_leak_generic_types")
{
CheckResult result = check(R"(
local function f(y)
-- this will only typecheck if we infer z: any
-- so f: (any)->(any)
local z = y
local function id(x)
z = x -- this assignment is what forces z: any
return x
end
local x: string = id("hi")
local y: number = id(37)
return z
end
-- so this assignment should fail
local b: boolean = f(true)
)");
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LUAU_REQUIRE_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "dont_leak_inferred_generic_types")
{
CheckResult result = check(R"(
local function f(y)
local z = y
local function id(x)
z = x
return x
end
local x: string = id("hi")
local y: number = id(37)
end
)");
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LUAU_REQUIRE_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "dont_substitute_bound_types")
{
CheckResult result = check(R"(
type T = { m: <a>(a) -> T }
function f(t : T)
local x: T = t.m(37)
end
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "dont_unify_bound_types")
{
CheckResult result = check(R"(
type F = <a>() -> <b>(a, b) -> a
type G = <b>(b, b) -> b
local f: F = function<a>()
local x
return function<b>(y: a, z: b): a
if not(x) then x = y end
return x
end
end
-- This assignment shouldn't typecheck
-- If it does, it means we instantiated
-- f as () -> <b>(X, b) -> X, then unified X to be b
local g: G = f()
-- Oh dear, if that works then the type system is unsound
local a : string = g("not a number", "hi")
local b : number = g(5, 37)
)");
LUAU_REQUIRE_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "mutable_state_polymorphism")
{
// Replaying the classic problem with polymorphism and mutable state in Luau
// See, e.g. Tofte (1990)
// https://www.sciencedirect.com/science/article/pii/089054019090018D.
CheckResult result = check(R"(
--!strict
-- Our old friend the polymorphic identity function
local function id(x) return x end
local a: string = id("hi")
local b: number = id(37)
-- This allows <a>(a)->a to be expressed without generic function syntax
type Id = typeof(id)
-- This function should have type
-- <a>() -> (a) -> a
-- not type
-- () -> <a>(a) -> a
local function ohDear(): Id
local y
function oh(x)
-- Returns the same x every time it's called
if not(y) then y = x end
return y
end
return oh
end
-- oh dear, f claims to polymorphic which it shouldn't be
local f: Id = ohDear()
-- the first call sets y
local a: string = f("not a number")
-- so b has value "not a number" at run time
local b: number = f(37)
)");
LUAU_REQUIRE_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "rank_N_types_via_typeof")
{
CheckResult result = check(R"(
--!strict
local function id(x) return x end
local x: string = id("hi")
local y: number = id(37)
-- This allows <a>(a)->a to be expressed without generic function syntax
type Id = typeof(id)
-- The rank 1 restriction causes this not to typecheck, since it's
-- declared as returning a polytype.
local function returnsId(): Id
return id
end
-- So this won't typecheck
local f: Id = returnsId()
local a: string = f("hi")
local b: number = f(37)
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "duplicate_generic_types")
{
CheckResult result = check(R"(
function f<a,a>(x:a):a return x end
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
}
TEST_CASE_FIXTURE(Fixture, "duplicate_generic_type_packs")
{
CheckResult result = check(R"(
function f<a...,a...>() end
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
}
TEST_CASE_FIXTURE(Fixture, "typepacks_before_types")
{
CheckResult result = check(R"(
function f<a...,b>() end
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
}
TEST_CASE_FIXTURE(Fixture, "variadic_generics")
{
CheckResult result = check(R"(
function f<a>(...: a) end
type F<a> = (...a) -> ...a
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "generic_type_pack_syntax")
{
CheckResult result = check(R"(
function f<a...>(...: a...): (a...) return ... end
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK_EQ(toString(requireType("f")), "<a...>(a...) -> (a...)");
}
TEST_CASE_FIXTURE(Fixture, "generic_type_pack_parentheses")
{
CheckResult result = check(R"(
function f<a...>(...: a...): any return (...) end
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
}
TEST_CASE_FIXTURE(Fixture, "better_mismatch_error_messages")
{
CheckResult result = check(R"(
function f<T>(...: T...)
return ...
end
function g<T...>(a: T)
return a
end
)");
LUAU_REQUIRE_ERROR_COUNT(2, result);
SwappedGenericTypeParameter* fErr = get<SwappedGenericTypeParameter>(result.errors[0]);
REQUIRE(fErr);
CHECK_EQ(fErr->name, "T");
CHECK_EQ(fErr->kind, SwappedGenericTypeParameter::Pack);
SwappedGenericTypeParameter* gErr = get<SwappedGenericTypeParameter>(result.errors[1]);
REQUIRE(gErr);
CHECK_EQ(gErr->name, "T");
CHECK_EQ(gErr->kind, SwappedGenericTypeParameter::Type);
}
TEST_CASE_FIXTURE(Fixture, "reject_clashing_generic_and_pack_names")
{
CheckResult result = check(R"(
function f<a, a...>() end
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
DuplicateGenericParameter* err = get<DuplicateGenericParameter>(result.errors[0]);
REQUIRE(err != nullptr);
CHECK_EQ(err->parameterName, "a");
}
TEST_CASE_FIXTURE(Fixture, "instantiation_sharing_types")
{
CheckResult result = check(R"(
function f(z)
local o = {}
o.x = o
o.y = {5}
o.z = z
return o
end
local o1 = f(true)
local x1, y1, z1 = o1.x, o1.y, o1.z
local o2 = f("hi")
local x2, y2, z2 = o2.x, o2.y, o2.z
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK(requireType("x1") != requireType("x2"));
CHECK(requireType("y1") == requireType("y2"));
CHECK(requireType("z1") != requireType("z2"));
}
TEST_CASE_FIXTURE(Fixture, "quantification_sharing_types")
{
CheckResult result = check(R"(
function f(x) return {5} end
function g(x, y) return f(x) end
local z1 = f(5)
local z2 = g(true, "hi")
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK(requireType("z1") == requireType("z2"));
}
TEST_CASE_FIXTURE(Fixture, "typefuns_sharing_types")
{
CheckResult result = check(R"(
type T<a> = { x: {a}, y: {number} }
local o1: T<boolean> = { x = {true}, y = {5} }
local x1, y1 = o1.x, o1.y
local o2: T<string> = { x = {"hi"}, y = {37} }
local x2, y2 = o2.x, o2.y
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK(requireType("x1") != requireType("x2"));
CHECK(requireType("y1") == requireType("y2"));
}
TEST_CASE_FIXTURE(Fixture, "bound_tables_do_not_clone_original_fields")
{
CheckResult result = check(R"(
local exports = {}
local nested = {}
nested.name = function(t, k)
local a = t.x.y
return rawget(t, k)
end
exports.nested = nested
return exports
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
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TEST_CASE_FIXTURE(Fixture, "instantiated_function_argument_names")
{
ScopedFastFlag luauFunctionArgumentNameSize{"LuauFunctionArgumentNameSize", true};
CheckResult result = check(R"(
local function f<T, U...>(a: T, ...: U...) end
f(1, 2, 3)
)");
LUAU_REQUIRE_NO_ERRORS(result);
auto ty = findTypeAtPosition(Position(3, 0));
REQUIRE(ty);
ToStringOptions opts;
opts.functionTypeArguments = true;
CHECK_EQ(toString(*ty, opts), "(a: number, number, number) -> ()");
}
TEST_CASE_FIXTURE(Fixture, "error_detailed_function_mismatch_generic_types")
{
CheckResult result = check(R"(
type C = () -> ()
type D = <T>() -> ()
local c: C
local d: D = c
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
if (FFlag::LuauExtendedFunctionMismatchError)
CHECK_EQ(
toString(result.errors[0]), R"(Type '() -> ()' could not be converted into '<T>() -> ()'; different number of generic type parameters)");
else
CHECK_EQ(toString(result.errors[0]), R"(Type '() -> ()' could not be converted into '<T>() -> ()')");
}
TEST_CASE_FIXTURE(Fixture, "error_detailed_function_mismatch_generic_pack")
{
CheckResult result = check(R"(
type C = () -> ()
type D = <T...>() -> ()
local c: C
local d: D = c
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
if (FFlag::LuauExtendedFunctionMismatchError)
CHECK_EQ(toString(result.errors[0]),
R"(Type '() -> ()' could not be converted into '<T...>() -> ()'; different number of generic type pack parameters)");
else
CHECK_EQ(toString(result.errors[0]), R"(Type '() -> ()' could not be converted into '<T...>() -> ()')");
}
TEST_SUITE_END();