fix: route explicit ninja goals through the manifest, not the command line — 0.0.108

CHANGELOG.md

@@ -3,6 +3,18 @@
 > 本文件追踪 `mcpp-community/mcpp` 公开仓的版本演进。
 > 格式参考 [Keep a Changelog](https://keepachangelog.com/zh-CN/1.1.0/)。
 
+## [0.0.108] — 2026-07-26
+
+### 修复
+
+- **Windows:显式 ninja 目标集不再撑爆命令行(0.0.104 起的回归)。** `mcpp test` 会把每一个共享前置(除测试自身 main 外的全部编译单元 + 非测试链接产物)列为 ninja 目标,好让包内源码出错时报**一次**包级错误,而不是 N 次雷同的逐测试编译失败。对大包来说这就是几千个对象路径 —— FFmpeg 的 2281 个编译单元拼出 **50,781 字符**的 argv。Windows 把 argv 合并成单条命令串交给 cmd.exe,而后者上限 **8191 字符**,于是命令**根本没有执行**:返回的是 cmd.exe 的裸 127,ninja 和 mcpp 都没有机会打印任何东西。
+
+  症状因此极难归因:mcpp-index 的 Windows CI 自 0.0.104 起在 `ffmpeg` 成员上失败,日志里最后一行是无关的下载进度条,既没有 `build failed` 诊断,`target/.build_cache` 也没写出。它是全仓唯一大到能触发的成员,`mcpp build` / `mcpp run` 走 `default`(不带目标参数)则始终正常。
+
+  修法是把目标集合写进 build.ninja 的一条 phony 聚合边,命令行只留一个词。清单文件没有长度限制,ninja 仍在**一次调用**内构建整个集合,并行度不变。e2e 164 锁住该机制。
+
+  与 0.0.107 修掉的 soname 别名回归**同源**:都来自 0.0.104 引入的"显式 ninja 目标"([#274](https://github.com/mcpp-community/mcpp/pull/274))—— 一处设计改动,两个只在特定条件下现形的症状。
+
 ## [0.0.107] — 2026-07-25
 
 ### 修复

mcpp.toml

@@ -1,6 +1,6 @@
 [package]
 name        = "mcpp"
-version     = "0.0.107"
+version     = "0.0.108"
 description = "Modern C++ build & package management tool"
 license     = "Apache-2.0"
 authors     = ["mcpp-community"]

src/build/ninja_backend.cppm

@@ -1101,6 +1101,38 @@ std::string emit_ninja_string(const BuildPlan& plan) {
     return out;
 }
 
+// Name of the phony edge that aggregates an explicit goal set. Not a path —
+// ninja resolves it in the build dir, and no rule produces a file by this name.
+constexpr std::string_view kGoalPhony = "mcpp-requested-goals";
+
+// Explicit goals go into the MANIFEST, not onto ninja's command line.
+//
+// `mcpp test` names every shared prerequisite as a goal so a broken package
+// source fails once, as a package error, rather than N times as identical
+// per-test compile failures (see execute.cppm phase A). For a large package
+// that is thousands of object paths: FFmpeg's 2281 translation units produced
+// a 50,781-character argv. Windows joins argv into a single command string for
+// cmd.exe, which truncates at 8191 characters — the command never ran, and the
+// bare 127 came back with no output at all, from cmd.exe rather than from
+// ninja or mcpp.
+//
+// A phony edge expresses exactly the same goal set with a one-word command
+// line. The manifest has no length limit, and ninja still builds the whole set
+// in one invocation, so parallelism is unchanged.
+//
+// Returns the goal to put on the command line, or empty for "build default".
+std::string append_goal_phony(std::string& manifest,
+                              const std::vector<std::string>& goals) {
+    if (goals.empty()) return {};
+    manifest += std::format("\nbuild {} : phony", kGoalPhony);
+    for (auto const& g : goals) {
+        manifest += ' ';
+        manifest += escape_ninja_path(g);
+    }
+    manifest += '\n';
+    return std::string(kGoalPhony);
+}
+
 std::expected<BuildResult, BuildError> NinjaBackend::build(const BuildPlan& plan,
                                                            const BuildOptions& opts) {
     auto t0 = std::chrono::steady_clock::now();
@@ -1113,7 +1145,9 @@ std::expected<BuildResult, BuildError> NinjaBackend::build(const BuildPlan& plan
                                           plan.outputDir});
 
     auto ninja_path = plan.outputDir / "build.ninja";
-    write_file(ninja_path, emit_ninja_string(plan));
+    auto manifest = emit_ninja_string(plan);
+    auto goalArg = append_goal_phony(manifest, opts.ninjaTargets);
+    write_file(ninja_path, manifest);
 
     // compile_commands.json — via the dedicated module.
     auto flags = compute_flags(plan);
@@ -1201,9 +1235,11 @@ std::expected<BuildResult, BuildError> NinjaBackend::build(const BuildPlan& plan
     }
 
     // Explicit goal targets: ninja builds only these outputs (and their
-    // prerequisites). Used by `mcpp test` to isolate per-test compiles.
-    for (auto& t : opts.ninjaTargets)
-        nargv.push_back(t);
+    // prerequisites). Used by `mcpp test` to isolate per-test compiles. The set
+    // travels through the manifest as a phony edge (append_goal_phony), so the
+    // command line stays one word no matter how many goals there are.
+    if (!goalArg.empty())
+        nargv.push_back(goalArg);
 
     // Real env pairs for THIS run (the "@env" cache encoding above is only
     // for the fast path's later re-creation of the same environment).

src/toolchain/fingerprint.cppm

@@ -18,7 +18,7 @@ import mcpp.toolchain.detect;
 
 export namespace mcpp::toolchain {
 
-inline constexpr std::string_view MCPP_VERSION = "0.0.107";
+inline constexpr std::string_view MCPP_VERSION = "0.0.108";
 
 struct FingerprintInputs {
     Toolchain                       toolchain;

tests/e2e/164_ninja_goal_command_length.sh

@@ -0,0 +1,66 @@
+#!/usr/bin/env bash
+# requires:
+# 164_ninja_goal_command_length.sh — an explicit ninja goal set must travel
+# through the manifest, never on the command line.
+#
+# `mcpp test` names every shared prerequisite as a goal so that a broken package
+# source fails once as a package error instead of N times as identical per-test
+# compile failures. For a large package that is thousands of object paths:
+# FFmpeg's 2281 translation units produced a 50,781-character argv. Windows
+# joins argv into one command string for cmd.exe, which caps at 8191 characters
+# — the command never ran and a bare 127 came back, from cmd.exe, with no output
+# from either ninja or mcpp. mcpp-index's Windows job failed this way on the
+# ffmpeg member from 0.0.104 (which introduced explicit goals) onward.
+#
+# The fix routes the goal set into build.ninja as a phony edge and puts one word
+# on the command line. This test asserts that mechanism rather than the 8191
+# limit itself: reproducing the limit needs a package big enough to be far too
+# slow here, and the limit does not exist on Linux/macOS at all. What is
+# portable — and what actually regressed — is "goals go in the manifest".
+set -e
+
+TMP=$(mktemp -d)
+trap "rm -rf $TMP" EXIT
+cd "$TMP"
+
+mkdir -p proj/src proj/tests
+cat > proj/mcpp.toml <<'EOF'
+[package]
+name    = "goalset"
+version = "0.1.0"
+EOF
+
+# Enough units that a regression would be visible as a long argv, while still
+# building in a couple of seconds.
+for i in $(seq 1 30); do
+    echo "int unit_$i() { return $i; }" > "proj/src/unit_$i.cpp"
+done
+echo 'int main() { return 0; }' > proj/src/main.cpp
+cat > proj/tests/sanity.cpp <<'EOF'
+extern int unit_1();
+int main() { return unit_1() == 1 ? 0 : 1; }
+EOF
+
+cd proj
+"$MCPP" test > test.log 2>&1 || { cat test.log; echo "FAIL: mcpp test"; exit 1; }
+grep -q "sanity ... ok" test.log || { cat test.log; exit 1; }
+
+NINJA=$(find target -name build.ninja | head -1)
+[ -n "$NINJA" ] || { echo "FAIL: no build.ninja"; exit 1; }
+
+# The phony edge is how the goal set reaches ninja.
+grep -q "^build mcpp-requested-goals : phony " "$NINJA" || {
+    echo "FAIL: explicit goals must be aggregated into a phony edge"
+    grep -n "phony" "$NINJA" | head; exit 1; }
+
+# And the goals themselves must not have been left on a command line. mcpp
+# records the ninja program it ran in target/.build_cache; the goal set never
+# belongs there either.
+if [ -f target/.build_cache ]; then
+    if grep -qE 'obj/.*obj/.*obj/' target/.build_cache; then
+        echo "FAIL: goal paths leaked into the recorded ninja invocation"
+        cat target/.build_cache; exit 1
+    fi
+fi
+
+echo "PASS 164_ninja_goal_command_length"