# Building

## Requirements

- CMake 3.14+
- A C++17 compiler (GCC or Clang) with a working C compiler alongside it
- Git — [CLI11](https://github.com/CLIUtils/CLI11) and
  [CaDiCaL](https://github.com/arminbiere/cadical) are fetched and built
  from source automatically
- Linux. The runtime plugin loader (see {doc}`architecture`) uses
  `/proc/self/exe` and `dlopen`, so this build is currently Linux-only.

## Build

```bash
mkdir build && cd build
cmake ..
make
```

This produces two binaries in `build/`:

- `just_count` — the CLI tool
- `test_counter` — the test suite (run via `ctest` or directly)

as well as a `build/cadical-plugins/` directory containing one shared
library per bundled CaDiCaL version (see {doc}`architecture`).

## What happens during the build

`CMakeLists.txt`:

1. Runs `git describe --always --dirty --tags` at configure time and bakes
   the result into a generated `version.h`, alongside the default bundled
   CaDiCaL version — this is what `just_count --version` and the startup
   banner report.
2. Fetches CLI11 via `FetchContent` for command-line parsing.
3. For each entry in `CADICAL_VERSIONS` / `CADICAL_TAGS` (currently
   `3.0.0`, `2.2.1`, `1.9.5` — the first entry is the default; see
   {doc}`investigation` for why), builds that CaDiCaL release from source with
   `CFLAGS=-fPIC CXXFLAGS=-fPIC ./configure && make`, then links it into
   its own small shared-library plugin.
4. Builds `just_count` and `test_counter` against `counter_lib`, which
   contains no CaDiCaL code at all — only the runtime plugin loader.

Building three full CaDiCaL source trees takes a few minutes the first
time; incremental rebuilds after touching only `just_count`'s own sources
are fast.

## Adding another bundled CaDiCaL version

Add its version number and git tag to the parallel `CADICAL_VERSIONS` /
`CADICAL_TAGS` lists near the top of `CMakeLists.txt` and reconfigure —
`add_cadical_plugin()` handles building and wiring up the new plugin. If
the new version changes the `freeze`/`add`/`solve`/`val`/`set` signatures
used by `src/cadical_plugin_impl.cpp`, that file needs a matching update.

## Running the tests

```bash
cd build
ctest --output-on-failure
# or directly:
./test_counter
```