v2.6.1

Patch fixing some compile issues in specific situations in the recent release,
and a potential segmentation fault from specially crafted config files

Added

• Added CI tests for install and package management on macos-arm64 #1238

Fixed

• Fixed incorrect links to validator examples. #1239
• Fixed incorrect inclusion of definition for extra validators #1238
• Fixed fuzz generated failure from crafted files introduced in recent release
  #1238
• Removed some usage of static const std::string in inline function that had
  potential memory issues when CLI11 is used with shared libraries, this likely
  isn't a bug but the fix did result in smaller code size so was kept. #1244

v2.6.0

Version 2.6.0

This version adds finer grained control of when option callbacks are executed,
and further refinements in the help formatting. It also fixes a number of bugs
in type support and the ordering of options. The other major change is moving
Extra Validators to a new file which can be disabled for slightly faster
compilation if not used, and allowing additional future Validators to be easily
added.

Added

• Added option to align long options with a ratio via
  long_option_alignment_ratio in the formatter. This allows more control over
  help output formatting. #1185
• Added support for std::string_view in the as<T> method on options.
  #1187
• Added flags on the formatter to disable formatting for the description and
  footer, allowing custom formatting such as word art. #1150
• Added subcommand prefix matching as a modifier to CLI::App. Also included an
  example of close matching logic. #1152
• Added additional fuzzing mechanics, including fuzzing subcommands, and
  improved handling of edge cases. #1170
• Added new tests for array options and fixed ambiguity between tuple and
  container conversions. #1136
• Added ability to use rvalue references in add_flag descriptions. #1173
• Added CMake presets for default and tidy builds. #1181
• Added several validator examples and documentation #1192
• Added permission validators for files and directories #1203
• Added fine grained control for option callback priority, and in what order
  options including help execute in the processing sequence. #1226
• Added github action to link with future testing is oss-fuzz #1225

Changed

• Moved several of the validators to ExtraValidators.hpp and
  ExtraValidators_inl.hpp files, The compilation of these nonessential
  validators can be disabled by setting CLI11_DISABLE_EXTRA_VALIDATORS to
  OFF. Future additional validators will be behind a compile flag
  CLI11_ENABLE_EXTRA_VALIDATORS. All non-essential validators will be under
  this option with version 3.0. #1192
• Updated processing order: requirements are now checked before callbacks,
  avoiding unexpected side effects. #1186
• Updated minimum required CMake version to 3.14+. #1182
• Improved Meson build: support for building shared precompiled libraries,
  pkgconfig, and header installation. #1167
• Improved fuzzing tests with new failure cases and extended coverage. #1164
• Updated CI to remove deprecated images and add new ones (Windows-2022/2025,
  arm64, FreeBSD). #1172, #1178
• Updated license file to include the correct version number for packagers.
  #1180

Fixed

• Fixed issue with IPV4 validator where it would allow a trailing .. #1192
• Fixed edge case where a missing config file and no default caused a segfault.
  #1199
• Fixed issue with TOML multiline arrays when the first line contained only a
  single character. #1196
• Fixed default value conversion errors when locales added thousands separators.
  #1160
• Fixed multiple footer printing in help output for option groups. #1161
• Fixed incorrect argument order in extras error messages. #1162
• Fixed reversed argument order in unexpected argument error messages. #1158
• Fixed ambiguity with vector<array> options. #1147
• Fixed bug parsing negative floating point values without a leading zero.
  #1140
• Fixed spelling mistake in Error.hpp. #1129
• Fixed compilation issue with MSVC 2017. #1143
• Fixed issue with default strings of arrays in config output. #1155
• Fixed fuzzing issues with NaNs and certain error pathways. #1138
• Fixed fuzzer misinterpreting --sub1.- as a short option. #1148
• Fixed issue where parse_order was not cleared on reset. #1218
• modify code to make compatible with /GR- option in MSVC #1206
• Fixed issue where the version flag would not take precedence over option
  requirements #1226
• Fixed extra newlines being printed if a footer was in use #1229

Version 2.5.0: Formatter

This version add a new formatter with improved control capabilities and output aligned with standards for help output. It also add a modifier to enable use of non-standard option names. Along with several bug fixes for edge cases in string and config file parsing.

• Better help formatter #866, this better aligns the help generation with UNIX standard and allows use in help2man. #1093
• Add mechanism to allow option groups to be hidden and all options be considered part of the parent for help display #1039
• Add a modifier to allow non-standard single flag option names such as -option. #1078
• Add modifier for subcommands to disable fallthrough which can resolve some issues with positional arguments #1073
• Add some polish to config file output removing some unnecessary output and add modifier to control output of default values #1075
• Add the ability to specify pair/tuple defaults and improved parsing #1081
• Bugfix: Take the configurability of an option name into account when determining naming conflicts #1049
• Bugfix: Fix an issue where an extra subcommand header was being printed in the output #1058
• Bugfix: Add additional fuzzing tests and fixes for a bug in escape string processing, and resolve inconsistencies in the handing of {} between command line parsing and config file parsing. #1060
• Bugfix: Improve handling of some ambiguities in vector input processing for config files, specifically in the case of vector of vector inputs. #1069
• Bugfix: Fix an issue in the handling of uint8_t enums, and some issues related to single element tuples #1087
• Bugfix: Fix an issue with binary strings containing a \x #1097
• Bugfix: Move the help generation priority so it triggers before config file processing #1106
• Bugfix: Fixed an issue where max/min on positionals was not being respected and optional positionals were being ignored #1108
• Bugfix: Fix an issue with strings which started and ended with brackets being misinterpreted as vectors. The parsing now has special handling of strings which start with [[ #1110
• Bugfix: Fix some macros for support in C++26 related to wide string parsing #1113
• Bugfix: Allow trailing spaces on numeric string conversions #1115
• Docs: Update pymod.find_installation to find python in meson.build #1076
• Docs: Add example for transform validators #689
• Docs: Fix several spelling mistakes #1101
• Backend: Update copyright dates to 2025 #1112
• Backend: Update CMake minimum version to 3.10 #1084

New Contributors

• @uilianries made their first contribution in #1061
• @LostInCompilation made their first contribution in #866
• @tansy made their first contribution in #975
• @JonathanGzzBen made their first contribution in #689
• @nshaheed made their first contribution in #1076
• @jmarrec made their first contribution in #1113

Full Changelog: v2.4.2...v2.5.0

Version 2.4.2: Build systems

This version improves support for alternative build systems, like Meson and Bazel. The single-include file now is in its own subdirectory. Several smaller fixes as well.

What's Changed

• Meson: fixes, cleanups, and modernizations #1024 & #1025
• Support building with Bazel #1033
• Restore non-arch dependent path for the pkgconfig file #1012
• Add get_subcommand_no_throw #1016
• Move single file to single-include folder #1030 & #1036
• Fixed app.set_failure_message(...) -> app.failure_message(...) #1018
• Add IWYU pragmas #1008
• Fix internal header include paths #1011
• Improved clarity in RequiredError #1029
• Added ability to use lexical_cast overloads constrained with enable_if #1021
• Bug fixes in latest release related to environmental variable parsing from option groups and unrecognized fields in a config file #1005

New Contributors

• @krico made their first contribution in #1018
• @dcbaker made their first contribution in #1024
• @gostefan made their first contribution in #1008
• @sifferman made their first contribution in #1029
• @calebzulawski made their first contribution in #1033

Full Changelog: v2.4.1...v2.4.2

Version 2.4.1

A transitive include that might be present in some standard libraries is now included directly. Also fixes a test on architectures that need libatomic linked and fixes an inadvertent breaking change regarding unused defaults for config files.

• Bugfix: Include cstdint #996
• Bugfix: Fix change in operation of config_ptr with unused default in the count method #1003
• Tests: Include libatomic if required for fuzzing test #1000

Full Changelog: v2.4.0...v2.4.1

Version 2.4.0

This version adds Unicode support, support for TOML standard including multiline strings, digit separators, string escape sequences,and dot notation. An initial round of a fuzzer was added to testing which has caught several bugs related to config file processing, and a few other edge cases not previously observed.

• Add Unicode support and bug fixes #804, #923, #876, #848, #832, #987
• Match TOML standard for string and numerical entries, multiline strings #968, #967,#964, #935
• Add validation for environmental variables #926
• Add an escape string transform #970
• Add A REVERSE multi-option policy to support multiple config files and other applications #918
• Add usage message replacement #768
• Allow using dot notation for subcommand arguments such as --sub1.field #789
• Bugfix: Fuzzing tests and fixes #930, #905, #874, #846
• Bugfix: Missing coverage tests #928
• Bugfix: CMake package and package config tests and fixes #916
• Bugfix: Support for Windows ARM compilation and tests #913, #914
• Bugfix: Environmental variable checks in non-triggered subcommands #904
• Bugfix: Environmental variables were not being correctly process by config pointer #891
• Bugfix: Undefined behavior in sum_string_vector #893
• Bugfix: Warnings and updates for CUDA 11 support #851
• Backend: Add tests for newer compilers (lost with Travis CI) #972
• Backend: Increase minimum CMake to 3.5 #898
• Backend: Remove integrated Conan support (provided now by Conan center) #853
• Tests: Support Catch2 Version 3 #896, #980

New Contributors

• @andreasxp made their first contribution in #804
• @Krzmbrzl made their first contribution in #844
• @ptheywood made their first contribution in #851
• @trokhymchuk made their first contribution in #893
• @peterh made their first contribution in #913
• @looopTools made their first contribution in #969

Full Changelog: v2.3.2...v2.4.0

Version 2.3.2: Minor maintenance

This version provides a few fixes collected over the last three months before adding features for 2.4.

• Bugfix: Consistently use ADL for lexical_cast, making it easier to extend for custom template types #820
• Bugfix: Tweak the parsing of files for flags with disable_flag_override #800]
• Bugfix: Handle out of bounds long long #807
• Bugfix: Spacing of make_description min option output #808
• Bugfix: Print last parsed subcommand's help message #822
• Bugfix: Avoid floating point warning in GCC 12 #803
• Bugfix: Fix a few gcc warnings #813
• Backend: Max CMake tested 3.22 -> 3.24 #823

New Contributors

• @DarkWingMcQuack made their first contribution in #803
• @SherlockInSpace made their first contribution in #808
• @captainurist made their first contribution in #820
• @VolkerChristian made their first contribution in #822

Full Changelog: v2.3.1...v2.3.2

Version 2.3.1: Missing function implementation

A function implementation was missing after the pre-compile move, missed due to the fact we lost 100% after losing coverage checking. We are working on filling out 100% coverage again to ensure this doesn't happen again!

• Bugfix: App::get_option_group implementation missing #793
• Bugfix: Fix spacing when setting an empty footer #796
• Bugfix: Address Klocwork static analysis checking issues #785

Version 2.3: Precompilation Support

This version adds a pre-compiled mode to CLI11, which allows you to precompile the library, saving time on incremental rebuilds, making CLI11 more competitive on compile time with classic compiled CLI libraries. The header-only mode is still default, and is not yet distributed via binaries.

• Add CLI11_PRECOMPILED as an option. #762
• Bugfix: Include <functional> in FormatterFwd #727
• Bugfix: Add missing Macros.hpp to Error.hpp #755
• Bugfix: Fix subcommand callback trigger #733
• Bugfix: Variable rename to avoid warning #734
• Bugfix: split_program_name single file name error #740
• Bugfix: Better support for min/max overrides on MSVC #741
• Bugfix: Support MSVC 2022 #748
• Bugfix: Support negated flag in config file #775
• Bugfix: Better errors for some confusing config file situations #781
• Backend: Restore coverage testing (lost with Travis CI) #747

New Contributors

• @shameekganguly made their first contribution in #727
• @PeteAudinate made their first contribution in #734
• @dherrera-fb made their first contribution in #762

Full Changelog: v2.2.0...v2.3.0

Version 2.2: Option and Configuration Flexibility

New features include support for output of an empty vector, a summing option policy that can be applied more broadly, and an option to validate optional arguments to discriminate from positional arguments. A new validator to check for files on a default path is included to allow one or more default paths for configuration files or other file arguments. A number of bug fixes and code cleanup for various build configurations. Clean up of some error outputs and extension of existing capability to new types or situations.

There is a possible minor breaking change in behavior of certain types which wrapped an integer, such as std::atomic<int> or std::optional<int> when used in a flag. The default behavior is now as a single argument value vs. summing all the arguments. The default summing behavior is now restricted to pure integral types, int64_t, int, uint32_t, etc. Use the new sum multi option policy to revert to the older behavior. The summing behavior on wrapper types was not originally intended.

• Add MultiOptionPolicy::Sum and refactor the add_flag to fix a bug when using std::optional<bool> as type. #709
• Add support for an empty vector result in TOML and as a default string. #660
• Add .validate_optional_arguments() to support discriminating positional arguments from vector option arguments. #668
• Add CLI::FileOnDefaultPath to check for files on a specified default path. #698
• Change default value display in help messages from =XXXX to [XXXXX] to make it clearer. #666
• Modify the Range Validator to support additional types and clean up the error output. #690
• Bugfix: The trigger on parse modifier did not work on positional arguments. #713
• Bugfix: The single header file generation was missing custom namespace generation. #707
• Bugfix: Clean up File Error handling in the argument processing. #678
• Bugfix: Fix a stack overflow error if nameless commands had fallthrough. #665
• Bugfix: A subcommand callback could be executed multiple times if it was a member of an option group. #666
• Bugfix: Fix an issue with vectors of multi argument types where partial argument sets did not result in an error. #661
• Bugfix: Fix an issue with type the template matching on C++20 and add some CI builds for C++20. #663
• Bugfix: Fix typo in C++20 detection on MSVC. #706
• Bugfix: An issue where the detection of RTTI being disabled on certain MSVC platforms did not disable the use of dynamic cast calls. #666
• Bugfix: Resolve strict-overflow warning on some GCC compilers. #666
• Backend: Add additional tests concerning the use of aliases for option groups in config files. #666
• Build: Add support for testing in meson and cleanup symbolic link generation. #701, #697
• Build: Support building in WebAssembly. #679