fix(ci): 分片数要数腿,不是数 job —— #184 把 65 个成员跑成了 29 个 (#186)

`Plan the shards` 用平台的矩阵条目数当分片数:

    linux:$(jq -r '[.include[]|select(.platform=="linux")]|length' ...)

在 #184 之前这两个数恰好相等,所以一直是对的。#184 给 linux 加了第二条工具链
腿之后不再相等:平台发 2 x 3 = 6 个条目,而切分仍然是 3 路,每个条目带的
shard 是 0..2。于是 plan 按 6 路切,job 只消费 0/1/2 —— 分到 3/4/5 的成员
一个都没跑。

65 个成员实际只跑了 29 个,而且是**静默**的:一个从未被分配的成员,和一个跑
过并通过的成员,在 CI 界面上长得一模一样。丢掉的里面有 ffmpeg、opencv-module
及其两个 feature 成员、catch2-v2、catch2-main、openssl —— 正是那条新腿被加进
来要测的东西。#184 全绿,但它想验证的路径一次都没执行。

改成读 `.shards`,也就是 emit() 已经写进每个条目、job 自己也在用
(matrix.shards)的那个值。plan 和消费方从此读同一个数,而不是两个碰巧相等
的数。

macos / windows 不受影响也不需要改:它们仍是单腿,条目数正好等于分片数 ——
这正是这个 bug 只咬 linux 的原因,也是它能在 review 里活下来的原因。

验证:拿 #184 那次运行的真实 matrix.json 跑 jq,linux 6 → 3,macos / windows
维持 2;plan_shards 三片合计从 29 回到 65/65,上面点名的成员全部归位。

Author: Sunrisepeak

.github/workflows/validate.yml

@@ -519,9 +519,24 @@ jobs:
           {
             printf '{'
             first=1
-            for spec in linux:$(jq -r '[.include[]|select(.platform=="linux")]|length' /tmp/matrix.json) \
-                        macos:$(jq -r '[.include[]|select(.platform=="macos")]|length' /tmp/matrix.json) \
-                        windows:$(jq -r '[.include[]|select(.platform=="windows")]|length' /tmp/matrix.json); do
+            # `.shards`, NOT the number of matrix entries.
+            #
+            # These stopped being the same number the moment linux grew a
+            # second toolchain leg: the platform emits 2 x 3 = 6 entries while
+            # the split is still 3 ways, and every entry carries shard 0..2.
+            # Planning 6 ways and consuming three of them dropped 36 of 65
+            # members on the floor — silently, because a member that is never
+            # assigned is indistinguishable from one that passed. `ffmpeg`,
+            # `opencv-module*`, `catch2-v2` and `openssl` were among them, on
+            # the very run that added the leg meant to test them.
+            #
+            # `.shards` is the value emit() already wrote per entry and the
+            # same one the job reads for its own `matrix.shards`, so plan and
+            # consumer now read one number instead of two that agreed by
+            # accident.
+            for spec in linux:$(jq -r 'first(.include[]|select(.platform=="linux")).shards' /tmp/matrix.json) \
+                        macos:$(jq -r 'first(.include[]|select(.platform=="macos")).shards' /tmp/matrix.json) \
+                        windows:$(jq -r 'first(.include[]|select(.platform=="windows")).shards' /tmp/matrix.json); do
               p=${spec%%:*}; n=${spec##*:}
               [ "$first" = 1 ] || printf ','
               first=0