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# The C+ Manual

C+ compiles to native code through LLVM. It has no garbage collector, no exceptions, no closures, no overloading, no implicit conversions, and no `null`. Memory is managed manually and checked through ownership and borrowing rules, with C ABI compatibility in both directions.

This manual documents **C+ 0.0.30**. The source of truth for behavior is the tagged compiler and package tree at [`v0.0.30`](https://github.com/netdur/cplus/tree/v0.0.30).

## Start here

- [Getting started](/docs/getting-started) installs the toolchain and builds the first program.
- [A tour of C+](/docs/tour) walks through a complete project in one sitting.
- [The C+ guide](/docs/guide) covers the judgment calls that syntax alone does not answer.
- [Language reference](/docs/reference) lists the complete surface compactly.
- [Language specification](/docs/spec) records the normative rules.
- [C+ 0.0.30 release notes](/docs/release-notes) record every shipped change and migration item.
- [Reproducible proofs](/prove) link claims to programs and commands that exercise them.

## Platforms in 0.0.30

C+ programs run across seven supported platform families:

```text
macos  linux  windows  ios  android  esp32  wasm
```

The native `cpc` toolchain runs on macOS, Linux, and Windows. It self-links executables on those hosts and cross-compiles static libraries and headers for iOS, Android, and ESP32. The `wasm` platform is used through `cpc-wasm`; it is not a native `cpc --target` value. See [Platforms and targets](/docs/targets) for target names and artifact behavior.

Facet has native backends for the supported application platforms:

| Platform | Facet backend | Status in 0.0.30 |
|---|---|---|
| macOS | [facet_appkit](/docs/packages/facet_appkit) | Supported |
| iOS | [facet_uikit](/docs/packages/facet_uikit) | Supported; simulator exercised, device build available |
| Android | [facet_android](/docs/packages/facet_android) | Supported |
| Linux | [facet_gtk](/docs/packages/facet_gtk) | Supported |
| Windows | [facet_winui](/docs/packages/facet_winui) | Supported (default; [facet_win32](/docs/packages/facet_win32) is deprecated as an explicit opt-out) |

Facet applications use [facet_runtime](/docs/packages/facet_runtime): register windows with `app.window(name, factory, chrome:)`, register routes on each window, and start the application with `App::run`.

## What changed in 0.0.30 (and 0.0.29)

- **WinUI 3 on Windows:** [facet_winui](/docs/packages/facet_winui), [agent_winui](/docs/packages/agent_winui), and [winui](/docs/packages/winui) are now the default Windows UI and agent backends for `facet_runtime` and `facet_agent`. `facet_win32` is deprecated and remains reachable as an explicit opt-out (`facet_runtime/win32::select()`).
- **App environment and assets ([appenv](/docs/packages/appenv)):** `appenv` provides `app_data_dir`, `cache_dir`, `no_backup_dir`, `resource_dir`, `asset_path`, `read_asset`, `read_asset_text`, and `app_id` from the first line of `main` on macOS, Linux, Windows, iOS, and Android. `cpc build` stages `<root>/assets/*` into `target/assets/<target>/<mode>/` and mirrors them beside self-linked binaries (`cpc build --print-asset-dir` prints the staged tree for external builders).
- **One `[package] app_id` across platforms:** `cpc init --app-id` writes `app_id` into `Cplus.toml` and each platform manifest; `cpc build` checks validity (**E0415**) and warns on drift (**W0008**).
- **Unified `hybrid_web` page bridge (`facet/hybrid_page`):** JavaScript calls `window.facet.postMessage(str)` up, native dispatches `HybridWebViewMessageReceived` (`e.detail.message`) down, and C+ reads payloads via `hybrid_page::message(sender)` across AppKit, UIKit, Android, GTK, and WinUI.
- **Liquid Glass & Material 3 UI parity:** iOS 26 Liquid Glass tab bars, blur effects, and push navigation in `facet_uikit`; Material 3 dynamic palette tokens, tab bars, bottom sheets, and dialogs in `facet_android`; bundled Material Symbols icon font (`facet/icon_font`), `named_size` typography roles, and file drop/save-panel support.
- **Language intrinsics & target features:** `#bitcast::[T](v)` reinterprets bits between same-width floats and integers (replacing `fN::from_bits` / `.to_bits()`, introduced in 0.0.29); `#target_feature("avx2")` queries enabled ISA extensions alongside `--target-cpu` and `--target-feature`; `stdlib/template` (`Template`) receives unjoined string literal parts and arguments; `stdlib/path` adds path manipulation helpers.
- **Compiler soundness, diagnostics, and doctests:** Generic `impl` templates are checked at definition time and treat unbounded `T` as move-only with potential drop; type aliases are resolved before borrow/move/drop checks; **W0009** warns on discarded `Status` returns; **E1010** rejects `@view` blocks on leaf controls (`scroll { ... }` now takes a `@view` block); `cpc test` extracts both bare ```` ``` ```` and ```` ```cplus ```` doctest fences and fails on unclosed fences.

## C plus packages

The language core supplies types, ownership, control flow, compilation, and the C ABI. The standard library, UI stack, platform bindings, services, data libraries, and numerical libraries live in packages. See the [package index](/docs/packages) and [modules and packages](/docs/modules-and-packages).

## Versioned manual

The clean `/docs` URLs always serve `Doc::CURRENT`. Frozen releases remain available under `/docs/{version}`. Every page also has a raw Markdown representation by appending `.md`; `/llms.txt` indexes the current manual and `/llms-full.txt` concatenates it.