[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
GitOrigin-RevId: 081c1db02dd2b48cf736d44862f7d7e8c2869577
diff --git a/include/format b/include/format
new file mode 100644
index 0000000..833423a
--- /dev/null
+++ b/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