fix(spirv): popen 是 POSIX 的,Windows 拼作 _popen

windows-2022 上 `mcpp.rules.spirv` 的宿主模块编译失败:

    rules/spirv.cppm:277:17: error: no member named 'popen' in the global namespace
    rules/spirv.cppm:282:7:  error: no type named 'pclose' in the global namespace

同一形状此前在 sycl 里已经处理过。空设备也一样(`/dev/null` / `NUL`)。两者都命名
成常量,让调用点在每个宿主上读起来一样 —— 另一种写法是每个调用点套一个 `#if`,而
被忘掉的那一个恰好是没人编译的那一个。

hip 那条 lane 的 clang++ 也补上后缀:它今天只到得了 Linux(NVIDIA 平台的头文件包
只为它发布),所以这段 Windows 拼写没有任何东西在走。仍然写下来,因为错误的路径会
把自己报成「工具链缺 clang」。

CI:跨平台 job 里把「每条规则都为本宿主编译过」挪到端到端那一步之前。它更便宜、答案
更有信息量;放在后面时,它的失败以别人的构建错误形态到达 —— 一个与它无关的 consumer
报 `no member named 'popen'`。

Author: Sunrisepeak

.github/workflows/ci.yml

@@ -461,6 +461,22 @@ jobs:
           echo "MCPP=$MCPP" >> "$GITHUB_ENV"
           echo "MCPP_VENDORED_XLINGS=$MCPP_VENDORED_XLINGS" >> "$GITHUB_ENV"
 
+      # FIRST, BECAUSE IT IS THE CHEAPER QUESTION AND THE MORE INFORMATIVE
+      # ANSWER. Every other step here drives one rule end to end and needs
+      # that rule's payload; this one names no accelerator, downloads nothing,
+      # and asks only whether all six modules COMPILE for this host -- which
+      # is the half of a rule that a Linux-only CI never sees. Run after the
+      # end-to-end step, its failure arrived as somebody else's build error:
+      # `no member named 'popen' in the global namespace`, reported against a
+      # consumer that had nothing to do with it.
+      - name: every rule module compiles for this host
+        working-directory: tests/all-rules-compile
+        run: |
+          set -e
+          "$MCPP" build
+          "$MCPP" run | tee run.log
+          grep -q '^all-rules-compile ok' run.log
+
       - name: rules-spirv through a consumer
         working-directory: tests/spirv-consumer
         run: |
@@ -473,20 +489,6 @@ jobs:
       # come from the GRAPH, not from the fixture. Without it, a fixture that
       # quietly regained an `[xlings.workspace]` would keep this green while the
       # claim stopped being true.
-      # THE STEP THAT MAKES THIS JOB WORTH ITS NAME. Above it, one rule is
-      # exercised because one rule's compiler is published for these hosts.
-      # Below it, EVERY rule is compiled for them -- including the ones whose
-      # payload reaches a device that macOS and Windows do not both have, and
-      # whose host-dependent code was therefore written without ever being
-      # compiled on the host it was written for.
-      - name: every rule module compiles for this host
-        working-directory: tests/all-rules-compile
-        run: |
-          set -e
-          "$MCPP" build
-          "$MCPP" run | tee run.log
-          grep -q '^all-rules-compile ok' run.log
-
       - name: the rule declared its own compiler
         working-directory: tests/spirv-consumer
         run: |

rules/hip.cppm

@@ -328,7 +328,17 @@ inline std::vector<edge> plan(std::span<const std::string> sources, options opt
     // everywhere else. `mcpp.rules.cuda` takes the same path for the same
     // reason.
     const std::string tcdir = mcpp::toolchain_dir();
+    // The suffix is the host's. This lane reaches only Linux today -- the
+    // NVIDIA-platform header package is published for it alone -- so the
+    // Windows spelling is not exercised by anything. It is written anyway,
+    // because the alternative is a path that is wrong on a host this rule
+    // will one day be asked about, and a wrong path reports itself as a
+    // missing toolchain.
+#if defined(_WIN32)
+    const std::string cc = tcdir + "/bin/clang++.exe";
+#else
     const std::string cc = tcdir + "/bin/clang++";
+#endif
     if (tcdir.empty() || !std::filesystem::exists(cc)) {
         std::cerr << std::format("mcpp.rules.hip: the NVIDIA platform compiles through clang, and this "
             "project's\n  toolchain has no clang++ at {}.\n"

rules/spirv.cppm

@@ -273,13 +273,38 @@ inline compiler find_compiler(const options& opt) {
 // magic, the second is the release. The release is what a floor compares, and
 // stating it as a fact is what makes a build log answer "which compiler
 // produced this SPIR-V" without anyone having to reproduce the build.
+// `popen` is POSIX and Windows spells it `_popen`; the null device differs
+// too. Both are named here so the call sites below read the same on every
+// host -- the alternative is a `#if` around each one, and the one that gets
+// forgotten is the one nobody compiles.
+inline FILE* open_pipe(const std::string& cmd) {
+#if defined(_WIN32)
+    return ::_popen(cmd.c_str(), "r");
+#else
+    return ::popen(cmd.c_str(), "r");
+#endif
+}
+inline void close_pipe(FILE* p) {
+#if defined(_WIN32)
+    ::_pclose(p);
+#else
+    ::pclose(p);
+#endif
+}
+inline constexpr const char* kNullDevice =
+#if defined(_WIN32)
+    "NUL";
+#else
+    "/dev/null";
+#endif
+
 inline std::string run_and_capture(const std::string& cmd) {
-    FILE* p = ::popen(cmd.c_str(), "r");
+    FILE* p = open_pipe(cmd);
     if (!p) return {};
     std::string text;
     char buf[512];
     while (std::fgets(buf, sizeof buf, p)) text += buf;
-    ::pclose(p);
+    close_pipe(p);
     return text;
 }
 
@@ -301,7 +326,8 @@ inline bool has_optimizer(const std::string& exe) {
 }
 
 inline std::string compiler_version(const compiler& cc) {
-    const std::string text = run_and_capture("\"" + cc.path + "\" --version 2>/dev/null");
+    const std::string text = run_and_capture("\"" + cc.path + "\" --version 2>"
+                                             + std::string(kNullDevice));
     // glslc: `shaderc v2026.3 2fbab05...` on the first line. glslang:
     // `Glslang Version: 11:15.1.0`, whose first field is the SPIR-V generator
     // magic and whose second is the release.