Lute check uses the new solver by default

lute/cli/src/tc.cpp

@@ -22,8 +22,6 @@ declare fs: {
     close: (file) -> (),
     read: (file) -> string,
     write: (file, string) -> (),
-    readfiletostring : (string) -> string,
-    writestringtofile : (string, string) -> (),
  -- is this right? I feel like we want a promise type here
     readasync : (string) -> string,
 }
@@ -186,6 +184,7 @@ int typecheck(const std::vector<std::string>& sourceFilesInput, LuteReporter& re
     LuteFileResolver fileResolver;
     Luau::LuteConfigResolver configResolver(mode);
     Luau::Frontend frontend(&fileResolver, &configResolver, frontendOptions);
+    frontend.setLuauSolverMode(Luau::SolverMode::New);
 
     Luau::registerBuiltinGlobals(frontend, frontend.globals);
     Luau::LoadDefinitionFileResult loadResult =

tests/cli/check.test.luau

@@ -0,0 +1,35 @@
+local fs = require("@std/fs")
+local path = require("@std/path")
+local process = require("@std/process")
+local system = require("@std/system")
+local test = require("@std/test")
+
+local lutePath = path.format(process.execpath())
+local tmpDir = system.tmpdir()
+
+test.suite("lute check", function(suite)
+	suite:case("uses new solver", function(assert)
+		local testFilePath = path.format(path.join(tmpDir, "check_new_solver.luau"))
+		fs.writestringtofile(
+			testFilePath,
+			[[
+function add(a,b)
+    return a + b
+end
+
+local vec2 = {}
+
+function vec2.new(x, y)
+    return setmetatable({x = x or 0, y = y or 0}, {__add = function(v1, v2) return {x = v1.x + v2.x, y = v1.y + v2.y} end})
+end
+
+add(1,1)
+add(vec2.new(0, 0), vec2.new(1,1))
+]]
+		)
+
+		local result = process.run({ lutePath, "check", testFilePath })
+		assert.eq(result.exitcode, 0)
+		fs.remove(testFilePath)
+	end)
+end)