compat.yaml-cpp 0.8.0/0.9.0 on openkal; openkal-ecosystem/openkal-compat labels; openkal measurement selects by change on x86_64-windows-musl; maintainer-hosted CN mirrors; a shorter README

.agents/docs/2026-09-23-add-yaml-cpp-plan.md

@@ -0,0 +1,59 @@
+# compat.yaml-cpp 0.8.0 / 0.9.0
+
+## Shape
+
+C++ source compat (Form B). Upstream's CMake target is `src/*.cpp` plus, with
+`YAML_CPP_BUILD_CONTRIB` at its default ON, `src/contrib/*.cpp`. No configure
+step, no generated header, no platform code in the library. 0.9.0 adds one TU
+(`src/fptostring.cpp`, over the vendored `src/contrib/dragonbox.h`) and one
+public header (`yaml-cpp/fptostring.h`); one glob covers both versions.
+
+Tags are spelled differently upstream (`0.8.0`, `yaml-cpp-0.9.0`), so the wrap
+dirs differ (`yaml-cpp-0.8.0/`, `yaml-cpp-yaml-cpp-0.9.0/`); `*` absorbs both.
+
+## Mirror
+
+gitcode `mcpp-res/yaml-cpp`, releases `0.8.0` and `0.9.0`, assets byte-identical
+to the GitHub tag archives (sha256 checked after download from both sides; each
+GitHub archive downloaded twice, digest stable).
+
+| version | sha256 |
+| --- | --- |
+| 0.8.0 | `fbe74bbdcee21d656715688706da3c8becfd946d92cd44705cc6098bb23b3a16` |
+| 0.9.0 | `25cb043240f828a8c51beb830569634bc7ac603978e0f69d6b63558dadefd49a` |
+
+## YAML_CPP_STATIC_DEFINE
+
+Upstream makes it a PUBLIC definition of a static build and reads it only in
+`include/yaml-cpp/dll.h`, which every public header reaches. A descriptor's
+`defines` are package-private, so `mcpp_generated/yaml-cpp/dll.h` defines it
+and `#include_next`s upstream's; `mcpp_generated` is first in `include_dirs`.
+The compile database confirms the consumer TU carries no `-D` for it, and the
+test's `#error` guard passes: the shim delivered it.
+
+## Upstream defect found by the test
+
+`GraphBuilderInterface` declares its destructor pure virtual and defines it
+nowhere, in both versions. Any derived class (upstream's own `GraphBuilder<Impl>`
+included) fails to link with `undefined symbol: ~GraphBuilderInterface()`
+unless its user defines it. The descriptor does not supply the definition: a
+consumer that already writes it would then get a duplicate symbol. The test
+writes it, as any consumer of the contrib API must.
+
+## Features
+
+None. Contrib is on by default upstream and is two small TUs; there is no
+optional component worth a gate.
+
+## Verification
+
+- `mcpp test -p yaml-cpp` / `-p yaml-cpp-v080` with the pinned mcpp 2026.9.18.3,
+  cold: `test result ok`. Objects: 32 + test TU (0.9.0), 31 + test TU (0.8.0),
+  equal to the source count.
+- 0.8.0 member asserts at compile time that `yaml-cpp/fptostring.h` is absent,
+  so it cannot pass by silently resolving 0.9.0.
+- openkal: both members are listed in `tests/openkal/members.toml`. Locally,
+  `x86_64-linux-gnu`: `runs (posix)` for both. The Windows leg is taken from
+  the PR's openkal-compat run (a local run with an unpinned mcpp failed inside
+  openkal-llvm-runtime's libunwind for the cli11 control member as well, so it
+  says nothing about this package).

.github/workflows/openkal-compat.yml

@@ -25,6 +25,7 @@ on:
     paths:
       - "pkgs/**/*.lua"
       - "tests/openkal/**"
+      - "tests/examples/**"
       - ".xpkgindex/openkal-compat.json"
       - ".github/workflows/openkal-compat.yml"
 
@@ -68,15 +69,17 @@ jobs:
         with:
           fetch-depth: 0
 
-      # A pull request measures the members its change can affect; the schedule
-      # and a request with no members measure every listed member.
+      # A pull request measures the members its change can affect (see
+      # `select_members` in compat.py: adding one member measures that member);
+      # the schedule and a request with no members measure every listed member.
       - name: Select the members
         id: select
         shell: bash
         run: |
           if [ "${{ github.event_name }}" = "pull_request" ]; then
-            files=$(git diff --name-only "origin/${{ github.base_ref }}...HEAD")
-            members=$(python3 tests/openkal/compat.py select $files)
+            base=$(git merge-base "origin/${{ github.base_ref }}" HEAD)
+            files=$(git diff --name-only "$base" HEAD)
+            members=$(python3 tests/openkal/compat.py select --base "$base" $files)
           else
             members="${{ github.event.inputs.members }}"
             [ -n "$members" ] || members=$(python3 tests/openkal/compat.py select tests/openkal/)