luau/tests/TypeInfer.provisional.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 "Fixture.h"
#include "doctest.h"
#include <algorithm>
LUAU_FASTFLAG(LuauEqConstraint)
using namespace Luau;
TEST_SUITE_BEGIN("ProvisionalTests");
// These tests check for behavior that differs from the final behavior we'd
// like to have. They serve to document the current state of the typechecker.
// When making future improvements, its very likely these tests will break and
// will need to be replaced.
/*
* This test falls into a sort of "do as I say" pit of consequences:
* Technically, the type of the type() function is <T>(T) -> string
*
* We thus infer that the argument to f is a free type.
* While we can still learn something about this argument, we can't seem to infer a union for it.
*
* Is this good? Maybe not, but I'm not sure what else we should do.
*/
TEST_CASE_FIXTURE(Fixture, "typeguard_inference_incomplete")
{
ScopedFastFlag luauTypeAliasPacks("LuauTypeAliasPacks", true);
const std::string code = R"(
function f(a)
if type(a) == "boolean" then
local a1 = a
elseif a.fn() then
local a2 = a
end
end
)";
const std::string expected = R"(
function f(a:{fn:()->(free,free...)}): ()
if type(a) == 'boolean'then
local a1:boolean=a
elseif a.fn()then
local a2:{fn:()->(free,free...)}=a
end
end
)";
CHECK_EQ(expected, decorateWithTypes(code));
}
TEST_CASE_FIXTURE(Fixture, "xpcall_returns_what_f_returns")
{
const std::string code = R"(
local a, b, c = xpcall(function() return 1, "foo" end, function() return "foo", 1 end)
)";
const std::string expected = R"(
local a:boolean,b:number,c:string=xpcall(function(): (number,string)return 1,'foo'end,function(): (string,number)return'foo',1 end)
)";
CHECK_EQ(expected, decorateWithTypes(code));
}
// We had a bug where if you have two type packs that looks like:
// { x, y }, ...
// { x }, ...
// It would infinitely grow the type pack because one WeirdIter is trying to catch up, but can't.
// However, the following snippet is supposed to generate an OccursCheckFailed, but it doesn't.
TEST_CASE_FIXTURE(Fixture, "weirditer_should_not_loop_forever")
{
// this flag is intentionally here doing nothing to demonstrate that we exit early via case detection
ScopedFastInt sfis{"LuauTypeInferTypePackLoopLimit", 50};
CheckResult result = check(R"(
local function toVertexList(vertices, x, y, ...)
if not (x and y) then return vertices end -- no more arguments
vertices[#vertices + 1] = {x = x, y = y} -- set vertex
return toVertexList(vertices, ...) -- recurse
end
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
// This should also generate an OccursCheckFailed error too, like the above toVertexList snippet.
// at least up until we can get Luau to recognize this code as a valid function that iterates over a list of values in the pack.
TEST_CASE_FIXTURE(Fixture, "it_should_be_agnostic_of_actual_size")
{
CheckResult result = check(R"(
local function f(x, y, ...)
if not y then return x end
return f(x, ...)
end
f(3, 2, 1, 0)
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
// Ideally setmetatable's second argument would be an optional free table.
// For now, infer it as just a free table.
TEST_CASE_FIXTURE(Fixture, "setmetatable_constrains_free_type_into_free_table")
{
CheckResult result = check(R"(
local a = {}
local b
setmetatable(a, b)
b = 1
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
TypeMismatch* tm = get<TypeMismatch>(result.errors[0]);
REQUIRE(tm);
CHECK_EQ("{- -}", toString(tm->wantedType));
CHECK_EQ("number", toString(tm->givenType));
}
TEST_CASE_FIXTURE(Fixture, "pass_a_union_of_tables_to_a_function_that_requires_a_table")
{
CheckResult result = check(R"(
local a: {x: number, y: number, [any]: any} | {y: number}
function f(t)
t.y = 1
return t
end
local b = f(a)
)");
LUAU_REQUIRE_NO_ERRORS(result);
// :(
// Should be the same as the type of a
REQUIRE_EQ("{| y: number |}", toString(requireType("b")));
}
TEST_CASE_FIXTURE(Fixture, "pass_a_union_of_tables_to_a_function_that_requires_a_table_2")
{
CheckResult result = check(R"(
local a: {y: number} | {x: number, y: number, [any]: any}
function f(t)
t.y = 1
return t
end
local b = f(a)
)");
LUAU_REQUIRE_NO_ERRORS(result);
// :(
// Should be the same as the type of a
REQUIRE_EQ("{| [any]: any, x: number, y: number |}", toString(requireType("b")));
}
TEST_CASE_FIXTURE(Fixture, "normal_conditional_expression_has_refinements")
{
CheckResult result = check(R"(
local foo: {x: number}? = nil
local bar = foo and foo.x -- TODO: Geez. We are inferring the wrong types here. Should be 'number?'.
)");
LUAU_REQUIRE_NO_ERRORS(result);
// Binary and/or return types are straight up wrong. JIRA: CLI-40300
CHECK_EQ("boolean | number", toString(requireType("bar")));
}
// Luau currently doesn't yet know how to allow assignments when the binding was refined.
TEST_CASE_FIXTURE(Fixture, "while_body_are_also_refined")
{
ScopedFastFlag sffs2{"LuauGenericFunctions", true};
ScopedFastFlag sffs5{"LuauParseGenericFunctions", true};
CheckResult result = check(R"(
type Node<T> = { value: T, child: Node<T>? }
local function visitor<T>(node: Node<T>, f: (T) -> ())
local current = node
while current do
f(current.value)
current = current.child -- TODO: Can't work just yet. It thinks 'current' can never be nil. :(
end
end
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
CHECK_EQ("Type 'Node<T>?' could not be converted into 'Node<T>'", toString(result.errors[0]));
}
// Originally from TypeInfer.test.cpp.
// I dont think type checking the metamethod at every site of == is the correct thing to do.
// We should be type checking the metamethod at the call site of setmetatable.
TEST_CASE_FIXTURE(Fixture, "error_on_eq_metamethod_returning_a_type_other_than_boolean")
{
CheckResult result = check(R"(
local tab = {a = 1}
setmetatable(tab, {__eq = function(a, b): number
return 1
end})
local tab2 = tab
local a = tab2 == tab
)");
LUAU_REQUIRE_ERROR_COUNT(1, result);
GenericError* ge = get<GenericError>(result.errors[0]);
REQUIRE(ge);
CHECK_EQ("Metamethod '__eq' must return type 'boolean'", ge->message);
}
// Requires success typing to confidently determine that this expression has no overlap.
TEST_CASE_FIXTURE(Fixture, "operator_eq_completely_incompatible")
{
CheckResult result = check(R"(
local a: string | number = "hi"
local b: {x: string}? = {x = "bye"}
local r1 = a == b
local r2 = b == a
)");
LUAU_REQUIRE_NO_ERRORS(result);
}
// Belongs in TypeInfer.refinements.test.cpp.
// We'll need to not only report an error on `a == b`, but also to refine both operands as `never` in the `==` branch.
TEST_CASE_FIXTURE(Fixture, "lvalue_equals_another_lvalue_with_no_overlap")
{
ScopedFastFlag sff1{"LuauEqConstraint", true};
CheckResult result = check(R"(
local function f(a: string, b: boolean?)
if a == b then
local foo, bar = a, b
else
local foo, bar = a, b
end
end
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK_EQ(toString(requireTypeAtPosition({3, 33})), "string"); // a == b
CHECK_EQ(toString(requireTypeAtPosition({3, 36})), "boolean?"); // a == b
CHECK_EQ(toString(requireTypeAtPosition({5, 33})), "string"); // a ~= b
CHECK_EQ(toString(requireTypeAtPosition({5, 36})), "boolean?"); // a ~= b
}
TEST_CASE_FIXTURE(Fixture, "bail_early_if_unification_is_too_complicated" * doctest::timeout(0.5))
{
ScopedFastInt sffi{"LuauTarjanChildLimit", 50};
ScopedFastInt sffi2{"LuauTypeInferIterationLimit", 50};
CheckResult result = check(R"LUA(
local Result
Result = setmetatable({}, {})
Result.__index = Result
function Result.new(okValue)
local self = setmetatable({}, Result)
self:constructor(okValue)
return self
end
function Result:constructor(okValue)
self.okValue = okValue
end
function Result:ok(val) return Result.new(val) end
function Result:a(p0, p1, p2, p3, p4) return Result.new((self.okValue)) or p0 or p1 or p2 or p3 or p4 end
function Result:b(p0, p1, p2, p3, p4) return Result:ok((self.okValue)) or p0 or p1 or p2 or p3 or p4 end
function Result:c(p0, p1, p2, p3, p4) return Result:ok((self.okValue)) or p0 or p1 or p2 or p3 or p4 end
function Result:transpose(a)
return a and self.okValue:z(function(some)
return Result:ok(some)
end) or Result:ok(self.okValue)
end
)LUA");
auto it = std::find_if(result.errors.begin(), result.errors.end(), [](TypeError& a) {
return nullptr != get<UnificationTooComplex>(a);
});
if (it == result.errors.end())
{
dumpErrors(result);
FAIL("Expected a UnificationTooComplex error");
}
}
TEST_CASE_FIXTURE(Fixture, "bail_early_on_typescript_port_of_Result_type" * doctest::timeout(1.0))
{
ScopedFastInt sffi{"LuauTarjanChildLimit", 400};
CheckResult result = check(R"LUA(
--!strict
local TS = _G[script]
local lazyGet = TS.import(script, script.Parent.Parent, "util", "lazyLoad").lazyGet
local unit = TS.import(script, script.Parent.Parent, "util", "Unit").unit
local Iterator
lazyGet("Iterator", function(c)
Iterator = c
end)
local Option
lazyGet("Option", function(c)
Option = c
end)
local Vec
lazyGet("Vec", function(c)
Vec = c
end)
local Result
do
Result = setmetatable({}, {
__tostring = function()
return "Result"
end,
})
Result.__index = Result
function Result.new(...)
local self = setmetatable({}, Result)
self:constructor(...)
return self
end
function Result:constructor(okValue, errValue)
self.okValue = okValue
self.errValue = errValue
end
function Result:ok(val)
return Result.new(val, nil)
end
function Result:err(val)
return Result.new(nil, val)
end
function Result:fromCallback(c)
local _0 = c
local _1, _2 = pcall(_0)
local result = _1 and {
success = true,
value = _2,
} or {
success = false,
error = _2,
}
return result.success and Result:ok(result.value) or Result:err(Option:wrap(result.error))
end
function Result:fromVoidCallback(c)
local _0 = c
local _1, _2 = pcall(_0)
local result = _1 and {
success = true,
value = _2,
} or {
success = false,
error = _2,
}
return result.success and Result:ok(unit()) or Result:err(Option:wrap(result.error))
end
Result.fromPromise = TS.async(function(self, p)
local _0, _1 = TS.try(function()
return TS.TRY_RETURN, { Result:ok(TS.await(p)) }
end, function(e)
return TS.TRY_RETURN, { Result:err(Option:wrap(e)) }
end)
if _0 then
return unpack(_1)
end
end)
Result.fromVoidPromise = TS.async(function(self, p)
local _0, _1 = TS.try(function()
TS.await(p)
return TS.TRY_RETURN, { Result:ok(unit()) }
end, function(e)
return TS.TRY_RETURN, { Result:err(Option:wrap(e)) }
end)
if _0 then
return unpack(_1)
end
end)
function Result:isOk()
return self.okValue ~= nil
end
function Result:isErr()
return self.errValue ~= nil
end
function Result:contains(x)
return self.okValue == x
end
function Result:containsErr(x)
return self.errValue == x
end
function Result:okOption()
return Option:wrap(self.okValue)
end
function Result:errOption()
return Option:wrap(self.errValue)
end
function Result:map(func)
return self:isOk() and Result:ok(func(self.okValue)) or Result:err(self.errValue)
end
function Result:mapOr(def, func)
local _0
if self:isOk() then
_0 = func(self.okValue)
else
_0 = def
end
return _0
end
function Result:mapOrElse(def, func)
local _0
if self:isOk() then
_0 = func(self.okValue)
else
_0 = def(self.errValue)
end
return _0
end
function Result:mapErr(func)
return self:isErr() and Result:err(func(self.errValue)) or Result:ok(self.okValue)
end
Result["and"] = function(self, other)
return self:isErr() and Result:err(self.errValue) or other
end
function Result:andThen(func)
return self:isErr() and Result:err(self.errValue) or func(self.okValue)
end
Result["or"] = function(self, other)
return self:isOk() and Result:ok(self.okValue) or other
end
function Result:orElse(other)
return self:isOk() and Result:ok(self.okValue) or other(self.errValue)
end
function Result:expect(msg)
if self:isOk() then
return self.okValue
else
error(msg)
end
end
function Result:unwrap()
return self:expect("called `Result.unwrap()` on an `Err` value: " .. tostring(self.errValue))
end
function Result:unwrapOr(def)
local _0
if self:isOk() then
_0 = self.okValue
else
_0 = def
end
return _0
end
function Result:unwrapOrElse(gen)
local _0
if self:isOk() then
_0 = self.okValue
else
_0 = gen(self.errValue)
end
return _0
end
function Result:expectErr(msg)
if self:isErr() then
return self.errValue
else
error(msg)
end
end
function Result:unwrapErr()
return self:expectErr("called `Result.unwrapErr()` on an `Ok` value: " .. tostring(self.okValue))
end
function Result:transpose()
return self:isOk() and self.okValue:map(function(some)
return Result:ok(some)
end) or Option:some(Result:err(self.errValue))
end
function Result:flatten()
return self:isOk() and Result.new(self.okValue.okValue, self.okValue.errValue) or Result:err(self.errValue)
end
function Result:match(ifOk, ifErr)
local _0
if self:isOk() then
_0 = ifOk(self.okValue)
else
_0 = ifErr(self.errValue)
end
return _0
end
function Result:asPtr()
local _0 = (self.okValue)
if _0 == nil then
_0 = (self.errValue)
end
return _0
end
end
local resultMeta = Result
resultMeta.__eq = function(a, b)
return b:match(function(ok)
return a:contains(ok)
end, function(err)
return a:containsErr(err)
end)
end
resultMeta.__tostring = function(result)
return result:match(function(ok)
return "Result.ok(" .. tostring(ok) .. ")"
end, function(err)
return "Result.err(" .. tostring(err) .. ")"
end)
end
return {
Result = Result,
}
)LUA");
auto it = std::find_if(result.errors.begin(), result.errors.end(), [](TypeError& a) {
return nullptr != get<UnificationTooComplex>(a);
});
if (it == result.errors.end())
{
dumpErrors(result);
FAIL("Expected a UnificationTooComplex error");
}
}
TEST_CASE_FIXTURE(Fixture, "table_subtyping_shouldn't_add_optional_properties_to_sealed_tables")
{
CheckResult result = check(R"(
--!strict
local function setNumber(t: { p: number? }, x:number) t.p = x end
local function getString(t: { p: string? }):string return t.p or "" end
-- This shouldn't type-check!
local function oh(x:number): string
local t: {} = {}
setNumber(t, x)
return getString(t)
end
local s: string = oh(37)
)");
// Really this should return an error, but it doesn't
LUAU_REQUIRE_NO_ERRORS(result);
}
// Should be in TypeInfer.tables.test.cpp
// It's unsound to instantiate tables containing generic methods,
// since mutating properties means table properties should be invariant.
// We currently allow this but we shouldn't!
TEST_CASE_FIXTURE(Fixture, "invariant_table_properties_means_instantiating_tables_in_call_is_unsound")
{
CheckResult result = check(R"(
--!strict
local t = {}
function t.m(x) return x end
local a : string = t.m("hi")
local b : number = t.m(5)
function f(x : { m : (number)->number })
x.m = function(x) return 1+x end
end
f(t) -- This shouldn't typecheck
local c : string = t.m("hi")
)");
// TODO: this should error!
// This should be fixed by replacing generic tables by generics with type bounds.
LUAU_REQUIRE_NO_ERRORS(result);
}
TEST_CASE_FIXTURE(Fixture, "self_recursive_instantiated_param")
{
ScopedFastFlag luauCloneCorrectlyBeforeMutatingTableType{"LuauCloneCorrectlyBeforeMutatingTableType", true};
ScopedFastFlag luauFollowInTypeFunApply{"LuauFollowInTypeFunApply", true};
ScopedFastFlag luauInstantiatedTypeParamRecursion{"LuauInstantiatedTypeParamRecursion", true};
// Mutability in type function application right now can create strange recursive types
// TODO: instantiation right now is problematic, it this example should either leave the Table type alone
// or it should rename the type to 'Self' so that the result will be 'Self<Table>'
CheckResult result = check(R"(
type Table = { a: number }
type Self<T> = T
local a: Self<Table>
)");
LUAU_REQUIRE_NO_ERRORS(result);
CHECK_EQ(toString(requireType("a")), "Table<Table>");
}
TEST_SUITE_END();