mcpp:plugins 0.1.0: the official rule collection, selected by features

.github/workflows/ci.yml

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+name: ci
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+env:
+  # The mcpp release the consumers build with. Raising it is what admits a
+  # member that relies on a newer engine; the README states each member's floor.
+  MCPP_VERSION: 2026.9.5.3
+
+jobs:
+  consumers:
+    name: consumers (linux x86_64)
+    runs-on: ubuntu-24.04
+    timeout-minutes: 60
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Cache the mcpp sandbox
+        uses: actions/cache@v4
+        with:
+          path: ~/.mcpp
+          key: mcpp-sandbox-${{ runner.os }}-${{ runner.arch }}-${{ env.MCPP_VERSION }}-${{ hashFiles('tests/*/mcpp.toml') }}
+          restore-keys: |
+            mcpp-sandbox-${{ runner.os }}-${{ runner.arch }}-${{ env.MCPP_VERSION }}-
+
+      - name: Fetch the released mcpp
+        run: |
+          curl -L -fsS --retry 3 --retry-all-errors -o mcpp.tar.gz \
+            "https://github.com/mcpp-community/mcpp/releases/download/v${MCPP_VERSION}/mcpp-${MCPP_VERSION}-linux-x86_64.tar.gz"
+          tar -xzf mcpp.tar.gz
+          MCPP="$PWD/mcpp-${MCPP_VERSION}-linux-x86_64/bin/mcpp"
+          "$MCPP" --version
+          "$MCPP" self config --mirror GLOBAL
+          echo "MCPP=$MCPP" >> "$GITHUB_ENV"
+
+      # The rule's output is a header holding the SPIR-V module; the program
+      # checks the magic number in its first word, so no Vulkan runtime is
+      # needed and what is tested is the rule and the engine path feeding it.
+      - name: rules-spirv through a consumer
+        working-directory: tests/spirv-consumer
+        run: |
+          "$MCPP" build
+          "$MCPP" run | tee run.log
+          grep -q '^magic=07230203' run.log
+
+      # Compiles the device unit on a machine with no GPU: the clang route
+      # produces sm_89 code from the payload toolkit. Running it needs a
+      # device, so the run is of the CPU variant, which the same seam serves.
+      - name: rules-cuda through a consumer
+        working-directory: tests/cuda-consumer
+        run: |
+          "$MCPP" build
+          "$MCPP" build --no-accel
+          "$MCPP" run --no-accel | tee run.log
+          grep -q '^12 24 36 48' run.log

README.md

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+# mcpp-plugins
+
+The build plugins the mcpp project maintains, published as one package,
+`mcpp:plugins`. A consumer selects the members it needs through features and
+imports each one from `build.mcpp` under the module name the member declares.
+
+```toml
+[dependencies.mcpp]
+plugins = { version = "0.1.0", features = ["rules-spirv"], host-module = true }
+```
+
+```cpp
+// build.mcpp
+import std;
+import mcpp;
+import mcpp.rules.spirv;
+
+int main() {
+    mcpp::rules::spirv::options opt;
+    opt.includes = { "shaders" };
+    return mcpp::rules::spirv::compile(opt) ? 0 : 1;
+}
+```
+
+## Naming
+
+| family | module name | purpose |
+|---|---|---|
+| rules | `mcpp.rules.<x>` | how one kind of translation unit is compiled by a compiler mcpp does not drive: the spelling of its flags, the probe of its toolkit, the actions it submits |
+| tools | `mcpp.tools.<x>` | a build-time utility independent of any compiler; see `tools/README.md` |
+| identity | `mcpp.plugins` | the lib root, compiled before every member; it states the collection's version |
+
+The `mcpp.` prefix is reserved for this package: mcpp warns when a module under
+it is declared by a package outside the `mcpp` namespace. `mcpp.build.*` is the
+engine's own module family and is not used here.
+
+## Members
+
+| feature | module | since mcpp | what it needs |
+|---|---|---|---|
+| `rules-cuda` | `mcpp.rules.cuda` | 2026.9.5.2 | the toolkit named in `[xlings.workspace]` (`xim:cuda-nvcc`, `xim:cuda-cudart`, and `xim:libcurand` for the clang route, whose wrapper includes a cuRAND header unconditionally), `[build] accel = "cuda…"`, a constrained glob for `*.cu`; the clang route with an LLVM toolchain, the nvcc route with a GCC one |
+| `rules-spirv` | `mcpp.rules.spirv` | 2026.9.5.3 | `xim:glslang` in `[xlings.workspace]`, `[build] accel = "vulkan1.2"`, a constrained glob for the shader stages; emits one header per shader through a `role = "source"` action |
+
+The floor is the mcpp release whose engine carries what the member relies on:
+`rules-spirv` needs the device-source table that classifies shader extensions,
+which 2026.9.5.3 introduced. The index descriptor states the floor; a project
+on an older mcpp is refused at resolution rather than at the first shader.
+
+## How the engine sees this package
+
+mcpp compiles every module interface unit among a host-module package's
+resolved sources as a host module of its own, the lib root first (2026.9.5.3+).
+`[features.<f>] sources` is what puts a member into that set, so the module set
+a consumer can import is exactly its feature set. A member is compiled alone,
+in the same command as the consumer's `build.mcpp`, and may import `std`,
+`mcpp` and `mcpp.plugins`.
+
+## Layout
+
+```
+mcpp.toml          the package: one feature per member
+src/plugins.cppm   export module mcpp.plugins;
+rules/<x>.cppm     export module mcpp.rules.<x>;
+tools/<x>.cppm     export module mcpp.tools.<x>;
+tests/<consumer>/  one project per member, built by CI with the pinned mcpp
+```
+
+## Adding a member
+
+1. One file, `rules/<x>.cppm` or `tools/<x>.cppm`, declaring its module name.
+   The engine owns the graph — the accelerator axis, the constrained globs,
+   the action edges, the fingerprint — and the member owns the spelling: which
+   tool, which flags, what is generated. A member does not read `/usr`; a tool
+   comes from `mcpp::toolchain_dir()`, `mcpp::xpkg_dir()` or an explicit option,
+   and a missing one is refused naming the `[xlings.workspace]` entry to add.
+2. A feature in `mcpp.toml` adding that one source.
+3. A consumer under `tests/` that builds through it and asserts on the
+   artefact, and a row in the table above with the mcpp floor.
+4. A version bump: mcpp identifies an installed package by `(name, version)`,
+   so a changed payload under an unchanged version is not reinstalled.
+
+## Releases
+
+A tag `v<version>` publishes the source archive; the index descriptor
+(`mcpp-index/pkgs/m/mcpp.plugins.lua`) names the GitHub archive and its GitCode
+mirror with one sha256.

mcpp.toml

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+[package]
+name        = "plugins"
+namespace   = "mcpp"
+version     = "0.1.0"
+description = "Official mcpp build plugins: rule packages under mcpp.rules.*, build-time utilities under mcpp.tools.*, each member selected by a feature"
+license     = "Apache-2.0"
+authors     = ["mcpp-community"]
+repo        = "https://github.com/mcpp-community/mcpp-plugins"
+
+[language]
+standard   = "c++23"
+modules    = true
+import_std = true
+
+# The lib root alone is compiled for a consumer that activates no feature. Each
+# member of the collection is a module interface unit that one feature adds to
+# the source set; mcpp compiles every interface unit among the resolved
+# sources as a host module under the name the unit declares (2026.9.5.3+).
+[build]
+sources = ["src/plugins.cppm"]
+
+[features]
+default     = []
+rules-cuda  = { sources = ["rules/cuda.cppm"] }
+rules-spirv = { sources = ["rules/spirv.cppm"] }
+
+[targets.plugins]
+kind = "lib"