test/std/utilities/format/format.functions/format.verify.cpp

//===----------------------------------------------------------------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: c++03, c++11, c++14, c++17

// TODO FMT This test should not require std::to_chars(floating-point)
// XFAIL: availability-fp_to_chars-missing

// Basic test to validate ill-formed code is properly detected.

// <format>

// template<class... Args>
//   string format(format-string<Args...> fmt, const Args&... args);
// template<class... Args>
//   wstring format(wformat-string<Args...> fmt, const Args&... args);

#include <format>

#include "test_macros.h"

// clang-format off

void f() {
  TEST_IGNORE_NODISCARD std::format("{"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format("}"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format("{}"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format("{0}"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format("{:-}", "Forty-two"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format("{:#}", "Forty-two"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format("{:L}", "Forty-two"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format("{0:{0}}", "Forty-two"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format("{:.42d}", "Forty-two"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format("{:d}", "Forty-two"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

#ifndef TEST_HAS_NO_WIDE_CHARACTERS
  TEST_IGNORE_NODISCARD std::format(L"{"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format(L"}"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format(L"{}"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format(L"{0}"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format(L"{:-}", L"Forty-two"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format(L"{:#}", L"Forty-two"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format(L"{:L}", L"Forty-two"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format(L"{0:{0}}", L"Forty-two"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format(L"{:.42d}", L"Forty-two"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}

  TEST_IGNORE_NODISCARD std::format(L"{:d}", L"Forty-two"); // expected-error-re{{call to consteval function '{{.*}}' is not a constant expression}}
  // expected-note@*:* {{non-constexpr function '__throw_format_error' cannot be used in a constant expression}}
#endif
}

struct tiny {
  int bit : 1;
};

void P2418()
{
  auto t = tiny{};
  TEST_IGNORE_NODISCARD std::format("{}", t.bit); // expected-error{{non-const reference cannot bind to bit-field 'bit'}}

#ifndef TEST_HAS_NO_WIDE_CHARACTERS
  TEST_IGNORE_NODISCARD std::format(L"{}", t.bit); // expected-error{{non-const reference cannot bind to bit-field 'bit'}}
#endif
}