[libc++] Implement format_error.

This is the first step at implementing <format>. It adds the <format> header
and implements the `format_error`. class.

Implemnts parts of:
-P0645 Text Formatting

Reviewed By: ldionne, #libc, miscco, curdeius

Differential Revision: https://reviews.llvm.org/D92214

libcxx/docs/Cxx2aStatusPaperStatus.csv

@@ -103,7 +103,7 @@
 "`P0466 <https://wg21.link/P0466>`__","LWG","Layout-compatibility and Pointer-interconvertibility Traits","Cologne","",""
 "`P0553 <https://wg21.link/P0553>`__","LWG","Bit operations","Cologne","|Complete|","9.0"
 "`P0631 <https://wg21.link/P0631>`__","LWG","Math Constants","Cologne","|Complete|","11.0"
-"`P0645 <https://wg21.link/P0645>`__","LWG","Text Formatting","Cologne","",""
+"`P0645 <https://wg21.link/P0645>`__","LWG","Text Formatting","Cologne","|In Progress|",""
 "`P0660 <https://wg21.link/P0660>`__","LWG","Stop Token and Joining Thread, Rev 10","Cologne","",""
 "`P0784 <https://wg21.link/P0784>`__","CWG","More constexpr containers","Cologne","|Complete|","12.0"
 "`P0980 <https://wg21.link/P0980>`__","LWG","Making std::string constexpr","Cologne","",""

libcxx/docs/FeatureTestMacroTable.rst

@@ -234,6 +234,8 @@ Status
     ------------------------------------------------- -----------------
     ``__cpp_lib_execution``                           *unimplemented*
     ------------------------------------------------- -----------------
+    ``__cpp_lib_format``                              *unimplemented*
+    ------------------------------------------------- -----------------
     ``__cpp_lib_generic_unordered_lookup``            ``201811L``
     ------------------------------------------------- -----------------
     ``__cpp_lib_int_pow2``                            ``202002L``

libcxx/include/CMakeLists.txt

@@ -99,6 +99,7 @@ set(files
   fenv.h
   filesystem
   float.h
+  format
   forward_list
   fstream
   functional

libcxx/include/format

@@ -0,0 +1,56 @@
+// -*- C++ -*-
+//===--------------------------- format -----------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_FORMAT
+#define _LIBCPP_FORMAT
+
+/*
+
+namespace std {
+  // [format.error], class format_error
+  class format_error : public runtime_error {
+  public:
+    explicit format_error(const string& what_arg);
+    explicit format_error(const char* what_arg);
+  };
+}
+
+*/
+
+#include <__config>
+#include <stdexcept>
+#include <version>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 17
+
+class _LIBCPP_EXCEPTION_ABI format_error : public runtime_error {
+public:
+  _LIBCPP_INLINE_VISIBILITY explicit format_error(const string& __s)
+      : runtime_error(__s) {}
+  _LIBCPP_INLINE_VISIBILITY explicit format_error(const char* __s)
+      : runtime_error(__s) {}
+  virtual ~format_error() noexcept;
+};
+
+#endif //_LIBCPP_STD_VER > 17
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP_FORMAT

libcxx/include/module.modulemap

@@ -292,6 +292,10 @@ module std [system] {
     header "filesystem"
     export *
   }
+  module format {
+    header "format"
+    export *
+  }
   module forward_list {
     header "forward_list"
     export initializer_list

libcxx/include/version

@@ -72,6 +72,7 @@ __cpp_lib_exchange_function                             201304L <utility>
 __cpp_lib_execution                                     201902L <execution>
                                                         201603L // C++17
 __cpp_lib_filesystem                                    201703L <filesystem>
+__cpp_lib_format                                        201907L <format>
 __cpp_lib_gcd_lcm                                       201606L <numeric>
 __cpp_lib_generic_associative_lookup                    201304L <map> <set>
 __cpp_lib_generic_unordered_lookup                      201811L <unordered_map> <unordered_set>
@@ -313,6 +314,7 @@ __cpp_lib_void_t                                        201411L <type_traits>
 # define __cpp_lib_erase_if                             202002L
 # undef  __cpp_lib_execution
 // # define __cpp_lib_execution                            201902L
+// # define __cpp_lib_format                               201907L
 # define __cpp_lib_generic_unordered_lookup             201811L
 # define __cpp_lib_int_pow2                             202002L
 // # define __cpp_lib_integer_comparison_functions         202002L

libcxx/lib/abi/x86_64-apple-darwin.libcxxabi.v1.stable.exceptions.no_new_in_libcxx.abilist

@@ -1039,6 +1039,9 @@
 {'is_defined': True, 'name': '__ZNSt3__112ctype_bynameIwED0Ev', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__112ctype_bynameIwED1Ev', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__112ctype_bynameIwED2Ev', 'type': 'FUNC'}
+{'is_defined': True, 'name': '__ZNSt3__112format_errorD0Ev', 'type': 'FUNC'}
+{'is_defined': True, 'name': '__ZNSt3__112format_errorD1Ev', 'type': 'FUNC'}
+{'is_defined': True, 'name': '__ZNSt3__112format_errorD2Ev', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__112future_errorC1ENS_10error_codeE', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__112future_errorC2ENS_10error_codeE', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__112future_errorD0Ev', 'type': 'FUNC'}
@@ -1985,6 +1988,7 @@
 {'is_defined': True, 'name': '__ZTINSt3__112codecvt_baseE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTINSt3__112ctype_bynameIcEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTINSt3__112ctype_bynameIwEE', 'size': 0, 'type': 'OBJECT'}
+{'is_defined': True, 'name': '__ZTINSt3__112format_errorE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTINSt3__112future_errorE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTINSt3__112strstreambufE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTINSt3__112system_errorE', 'size': 0, 'type': 'OBJECT'}
@@ -2193,6 +2197,7 @@
 {'is_defined': True, 'name': '__ZTSNSt3__112codecvt_baseE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTSNSt3__112ctype_bynameIcEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTSNSt3__112ctype_bynameIwEE', 'size': 0, 'type': 'OBJECT'}
+{'is_defined': True, 'name': '__ZTSNSt3__112format_errorE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTSNSt3__112future_errorE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTSNSt3__112strstreambufE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTSNSt3__112system_errorE', 'size': 0, 'type': 'OBJECT'}
@@ -2377,6 +2382,7 @@
 {'is_defined': True, 'name': '__ZTVNSt3__112bad_weak_ptrE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTVNSt3__112ctype_bynameIcEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTVNSt3__112ctype_bynameIwEE', 'size': 0, 'type': 'OBJECT'}
+{'is_defined': True, 'name': '__ZTVNSt3__112format_errorE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTVNSt3__112future_errorE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTVNSt3__112strstreambufE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTVNSt3__112system_errorE', 'size': 0, 'type': 'OBJECT'}

libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.exceptions.no_new_in_libcxx.abilist

@@ -726,6 +726,9 @@
 {'is_defined': True, 'name': '_ZNSt3__112ctype_bynameIwED0Ev', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__112ctype_bynameIwED1Ev', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__112ctype_bynameIwED2Ev', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt3__112format_errorD0Ev', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt3__112format_errorD1Ev', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt3__112format_errorD2Ev', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__112future_errorC1ENS_10error_codeE', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__112future_errorC2ENS_10error_codeE', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__112future_errorD0Ev', 'type': 'FUNC'}
@@ -1648,6 +1651,7 @@
 {'is_defined': True, 'name': '_ZTINSt3__112codecvt_baseE', 'size': 16, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTINSt3__112ctype_bynameIcEE', 'size': 24, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTINSt3__112ctype_bynameIwEE', 'size': 24, 'type': 'OBJECT'}
+{'is_defined': True, 'name': '_ZTINSt3__112format_errorE', 'size': 24, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTINSt3__112future_errorE', 'size': 24, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTINSt3__112strstreambufE', 'size': 24, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTINSt3__112system_errorE', 'size': 24, 'type': 'OBJECT'}
@@ -1776,6 +1780,7 @@
 {'is_defined': True, 'name': '_ZTSNSt3__112codecvt_baseE', 'size': 23, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTSNSt3__112ctype_bynameIcEE', 'size': 26, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTSNSt3__112ctype_bynameIwEE', 'size': 26, 'type': 'OBJECT'}
+{'is_defined': True, 'name': '_ZTSNSt3__112format_errorE', 'size': 23, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTSNSt3__112future_errorE', 'size': 23, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTSNSt3__112strstreambufE', 'size': 23, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTSNSt3__112system_errorE', 'size': 23, 'type': 'OBJECT'}
@@ -1908,6 +1913,7 @@
 {'is_defined': True, 'name': '_ZTVNSt3__112bad_weak_ptrE', 'size': 40, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTVNSt3__112ctype_bynameIcEE', 'size': 104, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTVNSt3__112ctype_bynameIwEE', 'size': 136, 'type': 'OBJECT'}
+{'is_defined': True, 'name': '_ZTVNSt3__112format_errorE', 'size': 40, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTVNSt3__112future_errorE', 'size': 40, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTVNSt3__112strstreambufE', 'size': 128, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTVNSt3__112system_errorE', 'size': 40, 'type': 'OBJECT'}

libcxx/src/CMakeLists.txt

@@ -12,6 +12,7 @@ set(LIBCXX_SOURCES
   condition_variable.cpp
   condition_variable_destructor.cpp
   exception.cpp
+  format.cpp
   functional.cpp
   future.cpp
   hash.cpp

libcxx/src/format.cpp

@@ -0,0 +1,15 @@
+//===------------------------- format.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
+//
+//===----------------------------------------------------------------------===//
+
+#include "format"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+format_error::~format_error() noexcept = default;
+
+_LIBCPP_END_NAMESPACE_STD

libcxx/test/libcxx/double_include.sh.cpp

@@ -91,6 +91,7 @@
 #    include <filesystem>
 #endif
 #include <float.h>
+#include <format>
 #include <forward_list>
 #ifndef _LIBCPP_HAS_NO_LOCALIZATION
 #    include <fstream>

libcxx/test/libcxx/min_max_macros.compile.pass.cpp

@@ -136,6 +136,8 @@ TEST_MACROS();
 #endif
 #include <float.h>
 TEST_MACROS();
+#include <format>
+TEST_MACROS();
 #include <forward_list>
 TEST_MACROS();
 #ifndef _LIBCPP_HAS_NO_LOCALIZATION

libcxx/test/libcxx/no_assert_include.compile.pass.cpp

@@ -84,6 +84,7 @@
 #    include <filesystem>
 #endif
 #include <float.h>
+#include <format>
 #include <forward_list>
 #ifndef _LIBCPP_HAS_NO_LOCALIZATION
 #    include <fstream>

libcxx/test/std/language.support/support.limits/support.limits.general/format.version.pass.cpp

@@ -0,0 +1,75 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// WARNING: This test was generated by generate_feature_test_macro_components.py
+// and should not be edited manually.
+//
+// clang-format off
+
+// <format>
+
+// Test the feature test macros defined by <format>
+
+/*  Constant            Value
+    __cpp_lib_format    201907L [C++20]
+*/
+
+#include <format>
+#include "test_macros.h"
+
+#if TEST_STD_VER < 14
+
+# ifdef __cpp_lib_format
+#   error "__cpp_lib_format should not be defined before c++20"
+# endif
+
+#elif TEST_STD_VER == 14
+
+# ifdef __cpp_lib_format
+#   error "__cpp_lib_format should not be defined before c++20"
+# endif
+
+#elif TEST_STD_VER == 17
+
+# ifdef __cpp_lib_format
+#   error "__cpp_lib_format should not be defined before c++20"
+# endif
+
+#elif TEST_STD_VER == 20
+
+# if !defined(_LIBCPP_VERSION)
+#   ifndef __cpp_lib_format
+#     error "__cpp_lib_format should be defined in c++20"
+#   endif
+#   if __cpp_lib_format != 201907L
+#     error "__cpp_lib_format should have the value 201907L in c++20"
+#   endif
+# else // _LIBCPP_VERSION
+#   ifdef __cpp_lib_format
+#     error "__cpp_lib_format should not be defined because it is unimplemented in libc++!"
+#   endif
+# endif
+
+#elif TEST_STD_VER > 20
+
+# if !defined(_LIBCPP_VERSION)
+#   ifndef __cpp_lib_format
+#     error "__cpp_lib_format should be defined in c++2b"
+#   endif
+#   if __cpp_lib_format != 201907L
+#     error "__cpp_lib_format should have the value 201907L in c++2b"
+#   endif
+# else // _LIBCPP_VERSION
+#   ifdef __cpp_lib_format
+#     error "__cpp_lib_format should not be defined because it is unimplemented in libc++!"
+#   endif
+# endif
+
+#endif // TEST_STD_VER > 20
+
+int main(int, char**) { return 0; }

libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp

@@ -67,6 +67,7 @@
     __cpp_lib_execution                            201603L [C++17]
                                                    201902L [C++20]
     __cpp_lib_filesystem                           201703L [C++17]
+    __cpp_lib_format                               201907L [C++20]
     __cpp_lib_gcd_lcm                              201606L [C++17]
     __cpp_lib_generic_associative_lookup           201304L [C++14]
     __cpp_lib_generic_unordered_lookup             201811L [C++20]
@@ -353,6 +354,10 @@
 #   error "__cpp_lib_filesystem should not be defined before c++17"
 # endif
 
+# ifdef __cpp_lib_format
+#   error "__cpp_lib_format should not be defined before c++20"
+# endif
+
 # ifdef __cpp_lib_gcd_lcm
 #   error "__cpp_lib_gcd_lcm should not be defined before c++17"
 # endif
@@ -884,6 +889,10 @@
 #   error "__cpp_lib_filesystem should not be defined before c++17"
 # endif
 
+# ifdef __cpp_lib_format
+#   error "__cpp_lib_format should not be defined before c++20"
+# endif
+
 # ifdef __cpp_lib_gcd_lcm
 #   error "__cpp_lib_gcd_lcm should not be defined before c++17"
 # endif
@@ -1541,6 +1550,10 @@
 #   error "__cpp_lib_filesystem should have the value 201703L in c++17"
 # endif
 
+# ifdef __cpp_lib_format
+#   error "__cpp_lib_format should not be defined before c++20"
+# endif
+
 # ifndef __cpp_lib_gcd_lcm
 #   error "__cpp_lib_gcd_lcm should be defined in c++17"
 # endif
@@ -2582,6 +2595,19 @@
 #   error "__cpp_lib_filesystem should have the value 201703L in c++20"
 # endif
 
+# if !defined(_LIBCPP_VERSION)
+#   ifndef __cpp_lib_format
+#     error "__cpp_lib_format should be defined in c++20"
+#   endif
+#   if __cpp_lib_format != 201907L
+#     error "__cpp_lib_format should have the value 201907L in c++20"
+#   endif
+# else // _LIBCPP_VERSION
+#   ifdef __cpp_lib_format
+#     error "__cpp_lib_format should not be defined because it is unimplemented in libc++!"
+#   endif
+# endif
+
 # ifndef __cpp_lib_gcd_lcm
 #   error "__cpp_lib_gcd_lcm should be defined in c++20"
 # endif
@@ -3788,6 +3814,19 @@
 #   error "__cpp_lib_filesystem should have the value 201703L in c++2b"
 # endif
 
+# if !defined(_LIBCPP_VERSION)
+#   ifndef __cpp_lib_format
+#     error "__cpp_lib_format should be defined in c++2b"
+#   endif
+#   if __cpp_lib_format != 201907L
+#     error "__cpp_lib_format should have the value 201907L in c++2b"
+#   endif
+# else // _LIBCPP_VERSION
+#   ifdef __cpp_lib_format
+#     error "__cpp_lib_format should not be defined because it is unimplemented in libc++!"
+#   endif
+# endif
+
 # ifndef __cpp_lib_gcd_lcm
 #   error "__cpp_lib_gcd_lcm should be defined in c++2b"
 # endif

libcxx/test/std/utilities/format/format.error/format.error.pass.cpp

@@ -0,0 +1,56 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// This test requires the dylib support introduced in D92214.
+// XFAIL: with_system_cxx_lib=macosx10.15
+// XFAIL: with_system_cxx_lib=macosx10.14
+// XFAIL: with_system_cxx_lib=macosx10.13
+// XFAIL: with_system_cxx_lib=macosx10.12
+// XFAIL: with_system_cxx_lib=macosx10.11
+// XFAIL: with_system_cxx_lib=macosx10.10
+// XFAIL: with_system_cxx_lib=macosx10.9
+
+// <format>
+
+// class format_error;
+
+#include <format>
+#include <type_traits>
+#include <cstring>
+#include <string>
+#include <cassert>
+
+#include "test_macros.h"
+
+int main(int, char**) {
+  static_assert(std::is_base_of_v<std::runtime_error, std::format_error>);
+  static_assert(std::is_polymorphic_v<std::format_error>);
+
+  {
+    const char* msg = "format_error message c-string";
+    std::format_error e(msg);
+    assert(std::strcmp(e.what(), msg) == 0);
+    std::format_error e2(e);
+    assert(std::strcmp(e2.what(), msg) == 0);
+    e2 = e;
+    assert(std::strcmp(e2.what(), msg) == 0);
+  }
+  {
+    std::string msg("format_error message std::string");
+    std::format_error e(msg);
+    assert(e.what() == msg);
+    std::format_error e2(e);
+    assert(e2.what() == msg);
+    e2 = e;
+    assert(e2.what() == msg);
+  }
+
+  return 0;
+}

libcxx/test/std/utilities/format/version.compile.pass.cpp

@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// <format>
+
+#include <format>
+
+#include "test_macros.h"
+
+#ifndef _LIBCPP_VERSION
+#  error _LIBCPP_VERSION not defined
+#endif
+
+// Required for MSVC internal test runner compatibility.
+int main(int, char**) { return 0; }

libcxx/utils/generate_feature_test_macro_components.py

@@ -270,6 +270,11 @@ feature_test_macros = [ add_version_header(x) for x in [
     "name": "__cpp_lib_filesystem",
     "values": { "c++17": 201703 },
     "headers": ["filesystem"],
+  }, {
+    "name": "__cpp_lib_format",
+    "values": { "c++20": 201907 },
+    "headers": ["format"],
+    "unimplemented": True,
   }, {
     "name": "__cpp_lib_gcd_lcm",
     "values": { "c++17": 201606 },