Gecode is an open source C++ toolkit for developing constraint-based systems and applications. Gecode provides a constraint solver with state-of-the-art performance while being modular and extensible.

You can find lots of information on Gecode's webpages, including how to download, compile, install, and use it.

In particular, Gecode comes with extensive tutorial and reference documentation.

CMake exposes options aligned with the Autoconf build switches. The minimum required CMake version is 3.21. configure.ac is the canonical autoconf source, and configure is generated from it. Version metadata shared by autoconf and CMake lives in gecode-version.m4. build/ is reserved for generated build outputs.

By default, CMake uses checked-in gecode/kernel/var-type.hpp and gecode/kernel/var-imp.hpp; regeneration is opt-in via -DGECODE_REGENERATE_VARIMP=ON. A nonempty GECODE_WITH_VIS list enables regeneration automatically and validates every specification during configuration; relative paths are resolved from the source directory. Build-time script execution uses uv run --script ... and requires Python 3.11 or newer. Autoconf builds require uv on PATH; CMake requires it only for generated-script paths such as -DGECODE_REGENERATE_VARIMP=ON and the doc target. Documentation generation requires Doxygen 1.17.0 or newer.

Autoconf make check deliberately does not build or run the CMake-only failpoint sources. Its ordinary test executable therefore never mixes process-global fault cases into the multi-threaded check run.

When changing generated-source inputs, run make regenerate after configuring the project. This uses the same version-checked workflow as CI and caches the Autoconf 2.72 bootstrap locally; Bison 3.8.2, Flex 2.6.4, and uv must be available. Ordinary C++ changes do not require regeneration.

GECODE_ENABLE_QT and GECODE_ENABLE_GIST accept AUTO, ON, and OFF. Use ON to require the dependency and fail configuration if it is missing or too old, OFF to disable it, and AUTO to use it when the local toolchain provides a supported Qt.

Deprecated compatibility aliases are accepted for the Gecode 6.x line: ENABLE_THREADS, ENABLE_GIST, BUILD_EXAMPLES, ENABLE_CPPROFILER.

For a Visual Studio + vcpkg workflow (including preset-based commands for MPFR), see docs/cmake-build.md.

Qt 6 is the preferred Qt line for Gecode builds. Qt 5.15 or newer remains supported for legacy environments, but older Qt releases are ignored unless GECODE_ENABLE_QT=ON, in which case configuration fails. On macOS, use a Qt build that supports the active macOS SDK; recent Qt 6 releases are the safest choice. Gist is opt-in for CMake builds on macOS. Use -DGECODE_ENABLE_GIST=ON when Qt is installed and its framework link interface is usable.

For CMake build/install workflows and downstream find_package(Gecode) usage, see docs/cmake-build.md.

Minimal downstream example:

find_package(Gecode CONFIG REQUIRED)
target_link_libraries(my_target PRIVATE Gecode::gecode)

Use Gecode_VERSION from package config for version checks.

Gecode 6.4.0 is distributed as source code. Source archives can be downloaded from GitHub or Gecode's webpages.

We happily accept smaller contributions and fixes, please provide them as pull requests against the main branch. For larger contributions, please get in touch.

Gecode is licensed under the MIT license.