gul-cpp · alt-graph · Feb 18, 2026 · Feb 18, 2026 · Feb 18, 2026 · Feb 18, 2026
diff --git a/README.md b/README.md
@@ -1,6 +1,6 @@
-# General Utility Library for C++17
+# General Utility Library for C++20
 
-The General Utility Library for C++17 (GUL17) contains often-used utility functions and
+The General Utility Library for C++20 (GUL20) contains often-used utility functions and
 types that form the foundation for other libraries and programs. The main fields covered
 by the library are:
 
@@ -15,7 +15,7 @@ by the library are:
   * Backports from new standard library extensions
 
 To get started, have a look at the
-[documentation website](https://gul-cpp.github.io/gul17/).
+[documentation website](https://gul-cpp.github.io/gul20/).
 
 Here you find more detailed information on:
 
@@ -29,20 +29,13 @@ Here you find more detailed information on:
 * [Versioning](#Versioning)
   * [Version number examples](#Version-number-examples)
 
-## Installing with vcpkg
-
-GUL17 is available from the [vcpkg](https://vcpkg.io/) package manager. Once you have
-vcpkg installed, just run:
-
-vcpkg install gul17
-
 ## Building <a name="Building"></a>
 
-Needless to say, GUL17 needs a C++17 compliant compiler. To get started, clone this
+Needless to say, GUL20 needs a C++20 compliant compiler. To get started, clone this
 repository:
 
-        git clone https://github.com/gul-cpp/gul17.git
-        cd gul17
+        git clone https://github.com/gul-cpp/gul20.git
+        cd gul20
 
 Use meson to configure the build you want to have. A list of the
 [build options](#Build-configuration-switches) is given below. Build directory name can be
@@ -181,9 +174,9 @@ generate the HTML pages.
 
 ## Versioning <a name="Versioning"></a>
 
-The version number for GUL17 resides in the LIBNO file.
+The version number for GUL20 resides in the LIBNO file.
 
-GUL17 follows a calendar-oriented versioning scheme with a version number of the
+GUL20 follows a calendar-oriented versioning scheme with a version number of the
 form YY.M.minor where YY stands for the last two digits of the year, M is the
 number of the month, and minor is a minor version number that starts from zero
 for each release in that month.

diff --git a/data/Doxyfile.in b/data/Doxyfile.in
@@ -32,7 +32,7 @@ DOXYFILE_ENCODING      = UTF-8
 # title of most generated pages and in a few other places.
 # The default value is: My Project.
 
-PROJECT_NAME           = "General Utility Library for C++17"
+PROJECT_NAME           = "General Utility Library for C++20"
 
 # The PROJECT_NUMBER tag can be used to enter a project or revision number. This
 # could be handy for archiving the generated documentation or if some version
@@ -811,7 +811,7 @@ RECURSIVE              = YES
 # Note that relative paths are relative to the directory from which doxygen is
 # run.
 
-EXCLUDE                = include/gul17/catch.h
+EXCLUDE                =
 
 # The EXCLUDE_SYMLINKS tag can be used to select whether or not files or
 # directories that are symbolic links (a Unix file system feature) are excluded

diff --git a/data/doxygen.h b/data/doxygen.h
@@ -4,7 +4,7 @@
  * \date    Created on August 24, 2018
  * \brief   Doxygen input file for the General Utility Library.
  *
- * \copyright Copyright 2018-2025 Deutsches Elektronen-Synchrotron (DESY), Hamburg
+ * \copyright Copyright 2018-2026 Deutsches Elektronen-Synchrotron (DESY), Hamburg
  *
  * 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
@@ -23,7 +23,7 @@
 /**
  * Namespace gul17 contains all functions and classes of the General Utility Library.
  */
-namespace gul17 {
+namespace GULNS {
 
 /**
  * \mainpage
@@ -32,7 +32,7 @@ namespace gul17 {
  *
  * \section introduction Introduction
  *
- * The General Utility Library for C++17 (GUL17) contains often-used utility functions and
+ * The General Utility Library for C++20 (GUL20) contains often-used utility functions and
  * types that form the foundation for other libraries and programs. The main fields
  * covered by the library are:
  *
@@ -58,9 +58,9 @@ namespace gul17 {
  * We strive for a very high quality level. To ensure this, we follow a list of
  * \ref quality_standards.
  *
- * \section who_is_using_the_library Who Is Using GUL17?
+ * \section who_is_using_the_library Who Is Using GUL20?
  *
- * GUL17 was developed at the German national particle accelerator laboratory
+ * GUL20 was developed at the German national particle accelerator laboratory
  * <a href="https://www.desy.de">DESY</a>. It was originally meant to provide a modern and
  * well-tested foundation for the <a href="https://doocs.desy.de/">DOOCS</a> control
  * system which drives most of the lab's accelerators. It is still used mainly in this
@@ -71,27 +71,31 @@ namespace gul17 {
  *
  * To use the library:
  *
- *  - Include the main header file \ref gul17/gul.h (or read more under
+ *  - Include the main header file \ref gul20/gul.h (or read more under
  *    \ref how_to_include_gul_headers).
- *  - Link your code against the library (-lgul17).
+ *  - Link your code against the library (-lgul20).
  *  - If you are on Windows, see \ref using_gul_on_windows.
  *
- * All functions and classes are enclosed in the namespace \ref gul17.
+ * All functions and classes are enclosed in the namespace \ref gul20.
  *
- * GUL17 requires at least C++17. It works fine with newer versions of the standard, but
- * might use its own backport types (e.g. gul17::expected) in function interfaces.
+ * GUL20 requires at least C++20. It works fine with newer versions of the standard, but
+ * might use its own backport types (e.g. gul20::expected) in function interfaces.
  *
  * \section installation Installation
  *
+ * \if GUL20_VCPKG_READY
  * If you are using the [vcpkg](https://vcpkg.io/) package manager, you can install the
  * library simply by running:
- * \verbatim vcpkg install gul17\endverbatim
- * Otherwise, you may have to build and install it manually. Have a look at the
- * [readme file on GitHub](https://github.com/gul-cpp/gul17/blob/main/README.md).
+ * \verbatim vcpkg install gul20\endverbatim
+ * Otherwise, you may have to build and install it manually.
+ * \endif
+ *
+ * Have a look at the
+ * [readme file on GitHub](https://github.com/gul-cpp/gul20/blob/main/README.md).
  *
  * \section source_code Obtaining the Source Code
  *
- * You can browse or clone the source code at https://github.com/gul-cpp/gul17.git.
+ * You can browse or clone the source code at https://github.com/gul-cpp/gul20.git.
  *
  * \section contributing Contributing
  *
@@ -112,38 +116,44 @@ namespace gul17 {
  */
 
 /**
- * \page how_to_include_gul_headers How to Include GUL17 Headers
+ * \page how_to_include_gul_headers How to Include GUL20 Headers
  *
- * All header files of the library reside under `gul17/` with no further subdirectories.
- * To get access to almost all of GUL17's functionality, it is sufficient to include the
+ * All header files of the library reside under `gul20/` with no further subdirectories.
+ * To get access to almost all of GUL20's functionality, it is sufficient to include the
  * all-in-one header:
  * \code
- * #include <gul17/gul.h>
+ * #include <gul20/gul.h>
  * \endcode
  *
- * Howard Hinnant's `gul17/date.h` header for calendar date functionality is not included
+ * Howard Hinnant's `gul20/date.h` header for calendar date functionality is not included
  * in this header file, chiefly because of its negative impact on compile times. Just
  * include it directly where needed.
  *
  * If you prefer to shave the last seconds off your build times, you are of course free to
- * include also the other GUL17 headers individually without going through `gul.h`. Just
+ * include also the other GUL20 headers individually without going through `gul.h`. Just
  * follow the documentation of the classes and functions you use to find the associated
  * header files.
  *
  * We do not guarantee that individual header file names will never change (except for
- * `gul17/gul.h`), but we can assure you that this will happen rarely, if ever.
+ * `gul20/gul.h`), but we can assure you that this will happen rarely, if ever.
  */
 
 /**
  * \page release_notes Release Notes
  *
- * GUL17 releases follow a calendar-oriented versioning scheme with a version number of
+ * GUL20 releases follow a calendar-oriented versioning scheme with a version number of
  * the form `YY.M.minor` where `YY` stands for the last two digits of the year, `M` is the
  * number of the month, and `minor` is a minor version number that starts from zero for
- * each release in that month. For instance, the first release in March 2025 was called
- * 25.3.0, the second could have been called 24.3.1. This is <em>not</em> semantic
+ * each release in that month. For instance, the first release in February 2026 was called
+ * 26.2.0, the second could have been called 26.2.1. This is <em>not</em> semantic
  * versioning.
  *
+ * \section changelog_gul20 GUL20 Versions
+ *
+ * - Initial release of GUL20. Compared to GUL17, backports of C++20 standard library
+ *   features (e.g. span, remove_cvref) are removed.
+ *
+ *
  * \section changelog_gul17 GUL17 Versions
  *
  * \subsection V26_2_0 Version 26.2.0
@@ -176,6 +186,7 @@ namespace gul17 {
  *   features (e.g. string_view, optional) are removed, and the build system is
  *   simplified.
  *
+ *
  * \section changelog_2_x GUL14: 2.x Versions
  *
  * \subsection V2_13_0 Version 2.13.0
@@ -354,14 +365,14 @@ namespace gul17 {
  *
  * The following individuals contributed to the General Utility Library:
  *
- * > Lars Fröhlich, Sören Grunewald, Olaf Hensler, Fini Jastrow, Josef Wilgen
+ * > Jan Behrens, Lars Fröhlich, Sören Grunewald, Olaf Hensler, Fini Jastrow
  *
  * Additional code distributed with this library was written by authors listed under
  * \ref additional_copyright_notices below.
  *
  * \section copyright_notice Copyright Notice
  *
- * Copyright 2018-2025 Deutsches Elektronen-Synchrotron (DESY), Hamburg
+ * Copyright 2018-2026 Deutsches Elektronen-Synchrotron (DESY), Hamburg
  *
  * 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
@@ -393,11 +404,6 @@ namespace gul17 {
  *     dedicated all copyright and related and neighboring rights to this software to the
  *     public domain worldwide. This software is distributed without any warranty.
  *     \ref license_cc0_public_domain and \ref expected.h for details).</dd>
- *
- * <dt>\ref span.h</dt>
- * <dd>Copyright 2018 Tristan Brindle.
- *     Distributed under the Boost Software License, Version 1.0 (see
- *     \ref license_boost_1_0 and \ref span.h for details).</dd>
  * </dl>
  */
 
@@ -536,7 +542,7 @@ namespace gul17 {
  * Furthermore, the library includes Howard Hinnant's date.h header, which extends C++17's
  * `<chrono>` library with types and functionality for handling calendar dates. Most of
  * this functionality has been standardized in C++20. Documentation is available on
- * [GitHub](https://howardhinnant.github.io/date/date.html); just note that the GUL17
+ * [GitHub](https://howardhinnant.github.io/date/date.html); just note that the GUL20
  * version lives in the namespace `gul17::date`.
  */
 
@@ -667,12 +673,6 @@ namespace gul17 {
  * \ref gul17::OverloadSet "OverloadSet":
  *     A class template that works like an overload set of functions, mainly for use with
  *     std::visit().
- *
- * \ref gul17::remove_cvref "remove_cvref":
- *     A metafunction to remove const, volatile, and reference qualifiers from a type.
- *     This is a backport of
- *     [std::remove_cvref](https://en.cppreference.com/w/cpp/types/remove_cvref) from
- *     C++20.
  */
 
 /**
@@ -691,17 +691,6 @@ namespace gul17 {
  *     error value. It should behave like
  *     [std::expected](https://en.cppreference.com/w/cpp/utility/expected)
  *     from C++23 for almost all use cases.
- *
- * \ref gul17::remove_cvref "remove_cvref":
- *     A metafunction to remove const, volatile, and reference qualifiers from a type.
- *     This is a backport of
- *     [std::remove_cvref](https://en.cppreference.com/w/cpp/types/remove_cvref) from
- *     C++20.
- *
- * \ref gul17::span "span":
- *     A view to a contiguous sequence of objects. It should behave like
- *     [std::span](https://en.cppreference.com/w/cpp/container/span) from C++20 for almost
- *     all use cases.
  */
 
 /**
@@ -711,10 +700,6 @@ namespace gul17 {
  * version 3 for its unit tests. Please refer to
  * https://github.com/catchorg/Catch2/blob/master/docs/tutorial.md for an introduction to
  * Catch2.
- *
- * \note
- * The predecessor library GUL14 included a header-only version of Catch2. This header is
- * no longer available in GUL17. Catch2 must be installed separately.
  */
 
 /**
@@ -980,9 +965,9 @@ namespace gul17 {
  */
 
 /**
- * \defgroup date_h gul17/date.h
+ * \defgroup date_h gul20/date.h
  * \brief Calendar date library by Howard Hinnant.
  * \see https://github.com/HowardHinnant/date
  */
 
-} // namespace gul17
+} // namespace GULNS
diff --git a/data/how_to_create_a_vcpkg_port.txt b/data/how_to_create_a_vcpkg_port.txt
@@ -1,17 +1,17 @@
-These are some notes on how to create a new vcpkg port for GUL17, e.g. after the
+These are some notes on how to create a new vcpkg port for GUL20, e.g. after the
 release of an update. This assumes that a fork of https://github.com/microsoft/vcpkg.git
 is checked out.
 
-1.  Edit ports/gul17/portfile.cmake
+1.  Edit ports/gul20/portfile.cmake
     Change REF to new version tag or git hash
     Change SHA512 to 0
-2.  Edit ports/gul17/vcpkg.json
+2.  Edit ports/gul20/vcpkg.json
     Change version number
 3.  Run vcpkg remove --outdated
-    This should remove the outdated GUL17 version (if any)
+    This should remove the outdated GUL20 version (if any)
 4.  Run vcpkg install gul17
     It should fail and show you the new SHA512 hash
-5.  Edit ports/gul17/portfile.cmake
+5.  Edit ports/gul20/portfile.cmake
     Change SHA512 to new hash
 6.  Add port to vcpkg repository
     git add ports/gul17

diff --git a/debian/copyright b/debian/copyright
@@ -1,15 +1,10 @@
 Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
 
 Files: *
-Copyright: 2018-2024 libgul contributors
-           2018-2024 DESY
+Copyright: 2018-2026 Deutsches Elektronen-Synchrotron (DESY)
 License: LGPL-2.1+
 
-Files: include/gul17/catch.h
-Copyright: 2019 Two Blue Cubes Ltd.
-License: BSL-1.0
-
-Files: include/gul17/date.h
+Files: include/gul20/date.h
 Copyright: 2015-2017 Howard Hinnant
            2016 Adrian Colomitchi
            2017 Florian Dang
@@ -19,16 +14,11 @@ Copyright: 2015-2017 Howard Hinnant
            2022 libgul contributors (L. Fröhlich)
 License: Expat
 
-Files: include/gul17/expected.h
+Files: include/gul20/expected.h
 Copyright: 2017 Sy Brand
            2023-2024 libgul contributors (L. Fröhlich)
 License: CC0
 
-Files: include/gul17/span.h
-Copyright: 2018 Tristan Brindle
-           2019 libgul contributors (L. Fröhlich)
-License: BSL-1.0
-
 License: LGPL-2.1+
  This package is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
@@ -44,31 +34,6 @@ License: LGPL-2.1+
  License along with this package; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 
-License: BSL-1.0
- Boost Software License - Version 1.0 - August 17th, 2003
- .
- Permission is hereby granted, free of charge, to any person or organization
- obtaining a copy of the software and accompanying documentation covered by
- this license (the "Software") to use, reproduce, display, distribute,
- execute, and transmit the Software, and to prepare derivative works of the
- Software, and to permit third-parties to whom the Software is furnished to
- do so, all subject to the following:
- .
- The copyright notices in the Software and this entire statement, including
- the above license grant, this restriction and the following disclaimer,
- must be included in all copies of the Software, in whole or in part, and
- all derivative works of the Software, unless such copies or derivative
- works are solely in the form of machine-executable object code generated by
- a source language processor.
- .
- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
- SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
- FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
- ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
- DEALINGS IN THE SOFTWARE.
-
 License: Expat
  Permission is hereby granted, free of charge, to any person obtaining
  a copy of this software and associated documentation files (the