gnulib: import regex module from gnulib.

commit f3553bdefc9202e81996c73686e3ca53cd827417 (HEAD -> master, origin/master, origin/HEAD)
Date:   Fri Jun 4 22:27:10 2021 +0200

$ gnulib-tool --source-base=gnulib --no-vc-files --import regex
gnulib-tool: *** minimum supported autoconf version is 2.64. Try adding AC_PREREQ([2.64]) to your configure.ac.
gnulib-tool: *** Stop.

edit AC_PREREQ version in configure.ac

$ gnulib-tool --source-base=gnulib --no-vc-files --import regex

gnulib/_Noreturn.h

@@ -0,0 +1,45 @@
+/* A C macro for declaring that a function does not return.
+   Copyright (C) 2011-2021 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify it
+   under the terms of the GNU Lesser General Public License as published
+   by the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#ifndef _Noreturn
+# if (defined __cplusplus \
+      && ((201103 <= __cplusplus && !(__GNUC__ == 4 && __GNUC_MINOR__ == 7)) \
+          || (defined _MSC_VER && 1900 <= _MSC_VER)) \
+      && 0)
+    /* [[noreturn]] is not practically usable, because with it the syntax
+         extern _Noreturn void func (...);
+       would not be valid; such a declaration would only be valid with 'extern'
+       and '_Noreturn' swapped, or without the 'extern' keyword.  However, some
+       AIX system header files and several gnulib header files use precisely
+       this syntax with 'extern'.  */
+#  define _Noreturn [[noreturn]]
+# elif ((!defined __cplusplus || defined __clang__) \
+        && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) \
+            || (!defined __STRICT_ANSI__ \
+                && (__4 < __GNUC__ + (7 <= __GNUC_MINOR__) \
+                    || (defined __apple_build_version__ \
+                        ? 6000000 <= __apple_build_version__ \
+                        : 3 < __clang_major__ + (5 <= __clang_minor__))))))
+   /* _Noreturn works as-is.  */
+# elif (2 < __GNUC__ + (8 <= __GNUC_MINOR__) || defined __clang__ \
+        || 0x5110 <= __SUNPRO_C)
+#  define _Noreturn __attribute__ ((__noreturn__))
+# elif 1200 <= (defined _MSC_VER ? _MSC_VER : 0)
+#  define _Noreturn __declspec (noreturn)
+# else
+#  define _Noreturn
+# endif
+#endif

gnulib/arg-nonnull.h

@@ -0,0 +1,26 @@
+/* A C macro for declaring that specific arguments must not be NULL.
+   Copyright (C) 2009-2021 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify it
+   under the terms of the GNU Lesser General Public License as published
+   by the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* _GL_ARG_NONNULL((n,...,m)) tells the compiler and static analyzer tools
+   that the values passed as arguments n, ..., m must be non-NULL pointers.
+   n = 1 stands for the first argument, n = 2 for the second argument etc.  */
+#ifndef _GL_ARG_NONNULL
+# if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 3) || defined __clang__
+#  define _GL_ARG_NONNULL(params) __attribute__ ((__nonnull__ params))
+# else
+#  define _GL_ARG_NONNULL(params)
+# endif
+#endif

gnulib/attribute.h

@@ -0,0 +1,218 @@
+/* ATTRIBUTE_* macros for using attributes in GCC and similar compilers
+
+   Copyright 2020-2021 Free Software Foundation, Inc.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Paul Eggert.  */
+
+/* Provide public ATTRIBUTE_* names for the private _GL_ATTRIBUTE_*
+   macros used within Gnulib.  */
+
+/* These attributes can be placed in two ways:
+     - At the start of a declaration (i.e. even before storage-class
+       specifiers!); then they apply to all entities that are declared
+       by the declaration.
+     - Immediately after the name of an entity being declared by the
+       declaration; then they apply to that entity only.  */
+
+#ifndef _GL_ATTRIBUTE_H
+#define _GL_ATTRIBUTE_H
+
+
+/* This file defines two types of attributes:
+   * C2X standard attributes.  These have macro names that do not begin with
+     'ATTRIBUTE_'.
+   * Selected GCC attributes; see:
+     https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html
+     https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html
+     https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html
+     These names begin with 'ATTRIBUTE_' to avoid name clashes.  */
+
+
+/* =============== Attributes for specific kinds of functions =============== */
+
+/* Attributes for functions that should not be used.  */
+
+/* Warn if the entity is used.  */
+/* Applies to:
+     - function, variable,
+     - struct, union, struct/union member,
+     - enumeration, enumeration item,
+     - typedef,
+   in C++ also: namespace, class, template specialization.  */
+#define DEPRECATED _GL_ATTRIBUTE_DEPRECATED
+
+/* If a function call is not optimized way, warn with MSG.  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_WARNING(msg) _GL_ATTRIBUTE_WARNING (msg)
+
+/* If a function call is not optimized way, report an error with MSG.  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_ERROR(msg) _GL_ATTRIBUTE_ERROR (msg)
+
+
+/* Attributes for memory-allocating functions.  */
+
+/* The function returns a pointer to freshly allocated memory.  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_MALLOC _GL_ATTRIBUTE_MALLOC
+
+/* ATTRIBUTE_ALLOC_SIZE ((N)) - The Nth argument of the function
+   is the size of the returned memory block.
+   ATTRIBUTE_ALLOC_SIZE ((M, N)) - Multiply the Mth and Nth arguments
+   to determine the size of the returned memory block.  */
+/* Applies to: function, pointer to function, function types.  */
+#define ATTRIBUTE_ALLOC_SIZE(args) _GL_ATTRIBUTE_ALLOC_SIZE (args)
+
+
+/* Attributes for variadic functions.  */
+
+/* The variadic function expects a trailing NULL argument.
+   ATTRIBUTE_SENTINEL () - The last argument is NULL (requires C99).
+   ATTRIBUTE_SENTINEL ((N)) - The (N+1)st argument from the end is NULL.  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_SENTINEL(pos) _GL_ATTRIBUTE_SENTINEL (pos)
+
+
+/* ================== Attributes for compiler diagnostics ================== */
+
+/* Attributes that help the compiler diagnose programmer mistakes.
+   Some of them may also help for some compiler optimizations.  */
+
+/* ATTRIBUTE_FORMAT ((ARCHETYPE, STRING-INDEX, FIRST-TO-CHECK)) -
+   The STRING-INDEXth function argument is a format string of style
+   ARCHETYPE, which is one of:
+     printf, gnu_printf
+     scanf, gnu_scanf,
+     strftime, gnu_strftime,
+     strfmon,
+   or the same thing prefixed and suffixed with '__'.
+   If FIRST-TO-CHECK is not 0, arguments starting at FIRST-TO_CHECK
+   are suitable for the format string.  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_FORMAT(spec) _GL_ATTRIBUTE_FORMAT (spec)
+
+/* ATTRIBUTE_NONNULL ((N1, N2,...)) - Arguments N1, N2,... must not be NULL.
+   ATTRIBUTE_NONNULL () - All pointer arguments must not be null.  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_NONNULL(args) _GL_ATTRIBUTE_NONNULL (args)
+
+/* The function's return value is a non-NULL pointer.  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_RETURNS_NONNULL _GL_ATTRIBUTE_RETURNS_NONNULL
+
+/* Warn if the caller does not use the return value,
+   unless the caller uses something like ignore_value.  */
+/* Applies to: function, enumeration, class.  */
+#define NODISCARD _GL_ATTRIBUTE_NODISCARD
+
+
+/* Attributes that disable false alarms when the compiler diagnoses
+   programmer "mistakes".  */
+
+/* Do not warn if the entity is not used.  */
+/* Applies to:
+     - function, variable,
+     - struct, union, struct/union member,
+     - enumeration, enumeration item,
+     - typedef,
+   in C++ also: class.  */
+#define MAYBE_UNUSED _GL_ATTRIBUTE_MAYBE_UNUSED
+
+/* The contents of a character array is not meant to be NUL-terminated.  */
+/* Applies to: struct/union members and variables that are arrays of element
+   type '[[un]signed] char'.  */
+#define ATTRIBUTE_NONSTRING _GL_ATTRIBUTE_NONSTRING
+
+/* Do not warn if control flow falls through to the immediately
+   following 'case' or 'default' label.  */
+/* Applies to: Empty statement (;), inside a 'switch' statement.  */
+#define FALLTHROUGH _GL_ATTRIBUTE_FALLTHROUGH
+
+
+/* ================== Attributes for debugging information ================== */
+
+/* Attributes regarding debugging information emitted by the compiler.  */
+
+/* Omit the function from stack traces when debugging.  */
+/* Applies to: function.  */
+#define ATTRIBUTE_ARTIFICIAL _GL_ATTRIBUTE_ARTIFICIAL
+
+/* Make the entity visible to debuggers etc., even with '-fwhole-program'.  */
+/* Applies to: functions, variables.  */
+#define ATTRIBUTE_EXTERNALLY_VISIBLE _GL_ATTRIBUTE_EXTERNALLY_VISIBLE
+
+
+/* ========== Attributes that mainly direct compiler optimizations ========== */
+
+/* The function does not throw exceptions.  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_NOTHROW _GL_ATTRIBUTE_NOTHROW
+
+/* Do not inline the function.  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_NOINLINE _GL_ATTRIBUTE_NOINLINE
+
+/* Always inline the function, and report an error if the compiler
+   cannot inline.  */
+/* Applies to: function.  */
+#define ATTRIBUTE_ALWAYS_INLINE _GL_ATTRIBUTE_ALWAYS_INLINE
+
+/* It is OK for a compiler to omit duplicate calls with the same arguments.
+   This attribute is safe for a function that neither depends on
+   nor affects observable state, and always returns exactly once -
+   e.g., does not loop forever, and does not call longjmp.
+   (This attribute is stricter than ATTRIBUTE_PURE.)  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_CONST _GL_ATTRIBUTE_CONST
+
+/* It is OK for a compiler to omit duplicate calls with the same
+   arguments if observable state is not changed between calls.
+   This attribute is safe for a function that does not affect
+   observable state, and always returns exactly once.
+   (This attribute is looser than ATTRIBUTE_CONST.)  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_PURE _GL_ATTRIBUTE_PURE
+
+/* The function is rarely executed.  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_COLD _GL_ATTRIBUTE_COLD
+
+/* If called from some other compilation unit, the function executes
+   code from that unit only by return or by exception handling,
+   letting the compiler optimize that unit more aggressively.  */
+/* Applies to: functions.  */
+#define ATTRIBUTE_LEAF _GL_ATTRIBUTE_LEAF
+
+/* For struct members: The member has the smallest possible alignment.
+   For struct, union, class: All members have the smallest possible alignment,
+   minimizing the memory required.  */
+/* Applies to: struct members, struct, union,
+   in C++ also: class.  */
+#define ATTRIBUTE_PACKED _GL_ATTRIBUTE_PACKED
+
+
+/* ================ Attributes that make invalid code valid ================ */
+
+/* Attributes that prevent fatal compiler optimizations for code that is not
+   fully ISO C compliant.  */
+
+/* Pointers to the type may point to the same storage as pointers to
+   other types, thus disabling strict aliasing optimization.  */
+/* Applies to: types.  */
+#define ATTRIBUTE_MAY_ALIAS _GL_ATTRIBUTE_MAY_ALIAS
+
+
+#endif /* _GL_ATTRIBUTE_H */

gnulib/btowc.c

@@ -0,0 +1,39 @@
+/* Convert unibyte character to wide character.
+   Copyright (C) 2008, 2010-2021 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2008.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <wchar.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+wint_t
+btowc (int c)
+{
+  if (c != EOF)
+    {
+      char buf[1];
+      wchar_t wc;
+
+      buf[0] = c;
+      if (mbtowc (&wc, buf, 1) >= 0)
+        return wc;
+    }
+  return WEOF;
+}