feat: generate compile database without building - #387
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Sunrisepeak merged 17 commits intoAug 10, 2026
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… replace - publish_compile_commands: treat a missing CDB (symlink_status type == not_found) as the normal first-build case instead of a fatal error. is_symlink sets ec on missing paths on every standard library (generic ENOENT on libstdc++/libc++, system ERROR_FILE_NOT_FOUND on MSVC), so no compile_commands.json was ever written on fresh workspaces and all CDB-dependent e2e tests failed. - close the existing-CDB ifstream before the atomic replace so Windows MoveFileExW can replace the destination (open handles cause Access denied / sharing violation). - unit tests: escape Windows backslash paths in the entry() JSON helper, write the mtime fixture in binary mode so on-disk bytes match on Windows, and add a regression test for publishing with no prior CDB.
Windows CDBs store file paths with backslashes, so `grep 'src/main.cpp'` never matched and the test failed on the Windows e2e shard once the CDB was actually being generated. Match either separator with `[\/]`.
Windows CDBs store paths with JSON-escaped backslashes (src\\main.cpp), so one-separator patterns still missed. Allow one or more separators.
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…g at its graph
The backend writes build.ninja before it honors dryRun, so `--configure-only`
rewrites the very file the P0 fast path replays — and a configure plan's graph
is not a normal build's graph: it carries the test targets and dev-dependencies,
so its `default` line names the TEST binaries and does not contain the package's
own target at all.
`target/.build_cache` was left untouched, and the fast path decides freshness by
comparing build.ninja's mtime against the SOURCES, never against the graph. So on
any already-built project:
mcpp build # default bin/app
mcpp build --configure-only # default bin/smoke <- same build.ninja
mcpp build # fast path -> links bin/smoke, never bin/app,
# prints `Finished dev in 0.04s`
which is the routine case, not a corner one: the whole point of the flag is that
an editor runs it continuously.
Drop the fast-path entry for the build dir whose graph was rewritten, before the
backend runs so a failed configure cannot leave the stale claim standing either.
Scoped to that one outputDir: other (target, profile, cache mode) triples own
different build dirs and keep their entries.
`write_build_cache`'s serializer is split out so the invalidation path rewrites
the file through the same spelling rather than a second one.
The e2e must NOT delete the built binary before the second build — a missing
output makes ninja fail in a way the fast path reads as a stale graph and falls
back to a full prepare, which hides the defect. Verified red (links `smoke`)
before the fix and green after.
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Review：架构对，一个真缺陷已修并入本 PR从架构 / 稳定性 / 简洁性 / 跨平台 / 可观测性 / 测试覆盖六个方向核过。结论是方案选对了：复用真实 下面是实测发现的问题，已经在本 PR 上改完并验证。 一、真缺陷：configure-only 会把构建快路径指向自己的图（已修）backend 在 $ mcpp build # default bin/repro
$ mcpp build --configure-only # default bin/smoke <- 同一个 build.ninja
$ mcpp build
Finished dev in 0.04s
$ ls target/*/*/bin
repro smoke # 链了测试，没链 target，还报了成功这不是边角情形：这个 flag 的全部意义就是编辑器会不停地跑它。 修法是在 backend 跑之前丢掉指向该构建目录的快路径条目（configure.cppm），失败的 configure 也不会留下过期声明。只作用于被重写的那一个 outputDir，别的 (target, profile, cache mode) 三元组各有自己的构建目录，实测 dev+release 两条条目只掉 dev 那条。
二、E2E 编号撞车（已修）
三、新加的守卫差点是假绿（已修）我给 e2e 补的快路径断言最初写成「先 另外把首次调用的 四、补 CHANGELOG
五、核过没问题的部分
六、验证本机 x86_64-linux-gnu：unit 76 个测试二进制全过；e2e 🤖 Generated with Claude Code |
…uced Windows links `fastpath.exe`; the new fast-path section hardcoded the POSIX spelling and failed at the baseline check before reaching the assertion it exists for (e2e 2/2 windows). The suffix is a host constant, so take it off the artifact `find` actually returned rather than branching on the platform.
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…#408) 图形栈不可用不是一个 bug,是三层各自独立的故障。追到代码之后,其中两层的既有结论 是错的 —— 按它们去修,修完还是坏的。 ## 三条被测量推翻的结论 1. #405 的 issue 根因是错的(我自己写的那条,而且是这个 issue 上第二次)。 它说「谓词漏判 ⇒ 不发 std 的 stage 边」。生成物否掉了它:边就在 build.ninja 第 65 行。 `scan_packages` 的 packages 本来就含依赖包根,谓词恒为真。真因是**没有任何边依赖 那条边**,ninja 于是从不执行它。按 issue 里的修法(entry.json 记 imports_std) 作用在一个已经为真的谓词上 —— 改完仍然坏。 2. mcpp-index 上 8 个图形成员全红不是数据缺陷。`xim:libglvnd@>=1.7.0.1` 在 xlings 2026.8.9.2 起解析正常(四段版本 semver 重写),红的原因是 index CI 钉在 mcpp 2026.8.8.2,它内带 xlings 2026.8.8.1 —— 正好落在修复之前。 xim-pkgindex 一个字都不用改。 3. 图形拿不到 GPU 的直接原因在 mcpp 自己的链接命令行里:全仓没有一处 `--disable-new-dtags`,唯一相关的一处显式写了 `--enable-new-dtags`。 ## 修复 - **#405** 缓存命中时,被恢复的包传递依赖的 std BMI 没有消费者。修法把它放进 `_mcpp_staged_cache` —— 那个聚合本来就是为「stage 边丢掉编译边携带的次序」建的, std BMI 是同一缺陷早一条边。不动 cache key / entry schema,现有缓存全部有效。 缓存 miss 时依赖在本地编译、把 std 边带进图,所以第一个构建它的人永远是好的、 之后每个人都坏 —— 这就是它伪装成升级回归的方式。 - **#407** 三种模式写同一个 build.ninja,快路径只比源码 mtime。改成让图自己声明形态 (`# mcpp:graph=normal|test`),快路径校验它即将重放的那张图。**读取侧不变式**, 并同时删掉 #387 留下的写入侧修补 —— 写入侧要求每个未来的图重写者都记得调用, 这正是 `mcpp test` 那半边在 `--configure-only` 修好之后仍然坏着的原因。 ## 新增 - **加载器标签契约**(`mcpp.build.loader_contract`):可执行 DT_RPATH、库 DT_RUNPATH。 DT_RUNPATH 只对携带它的对象**自己发起**的 dlopen 生效,而图形程序到驱动的三到四层 dlopen 都不是它发起的 —— 是 libGLX.so.0 代发的。所以决定能否上 GPU 的是标签不是路径。 反过来在库上强制 RPATH 有害(打断 eglInitialize),所以一分为二。链接期与 pack 的 patchelf 期读同一条契约。这是 xlings 图形栈设计里 E2(构建侧)的 mcpp 那一半。 - **rule E**:标签校验落在产物上,写进 resolution.json 的 `loader_tags`,warn-first。 记录而不只是告警 —— 只在沉默中通过的检查,和根本没跑的检查,输出完全相同。 - **pack 不再残留构建机路径**:此前只重写主二进制,bundle 进来的每个 .so 都保留着 指向构建机 xlings store 的绝对 RUNPATH。「依赖 xlings 生态」是设计选择, 「依赖这一台机器的这一份 store」是缺陷,而且在构建它的机器上跑得好好的。 **不碰动态加载器** —— 它不是被搜索的库,它是执行搜索的程序;patchelf 改它会让 self-contained 档在 main 之前段错误(30_pack_modes 抓到的)。 - **HOST-REQUIREMENTS**:自包含有底。驱动只能来自目标机器(与内核模块锁步 + 禁止 再分发),所以诚实产出是 bundle 加一份声明。带 discovery 列,因为几种发现机制 互不通用。 - **自带 libc 的档硬拒宿主能力**:self-contained 与 static 在 plan 期失败并指出改用 vendored。两者坏在同一件事上(#392/#401 的两个方向),此前都链得过去然后运行时崩。 - **`[[runtime.requirements]] discovery`**:声明式,mcpp 绝不推断 —— 从能力名推断 就是把 provider 专属知识写进 mcpp,`test_runtime_contract` 正是为此设的门。 - **artifact 身份判决**:resolution.json 每个 artifact 带 `identity` (ok/mismatch/missing/unverified),跟随符号链接。这是 mcpp 已经对私有 libc 执行的 规则的推广,纯路径事实。`why runtime` 的 `(none declared)` 改为 `(not declared by the environment — nothing to verify)`:有名无物是未验证,不是通过。 ## 变更 - 内带 xlings 升到 2026.8.10.4(16 个 pin 由 check_version_pins.sh 机器校验)。 ## 本地验证 - unit 77/77 通过(含新增 test_loader_contract:契约、图形态、宿主要求、身份判决)。 - e2e 183 通过 / 25 失败 / 8 跳过。**25 条里 24 条用已发布的 2026.8.8.2 逐条复现**, 同一个环境根因:本机共享 gcc 载荷的 specs 被历史安装污染 —— `--dynamic-linker` 指向已被改名的 glibc/2.44,rpath 里还有约 40 条来自已删除沙箱的 /tmp/tmp.* 条目。 第 25 条(30_pack_modes)是真回归,已定位并修复(不得 patchelf 动态加载器)。 - 每条新 e2e 都先证伪过:撤掉对应修改必须变红,并已实测。 Co-authored-by: speak-agent <248744407+speak-agent@users.noreply.github.com>
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Summary
mcpp build --configure-only, reusing the real build plan and existing build selectors while skipping ordinary compilation, linking, BMI cache population, and build-success cache writestests/**/*.cpp, matching[build].flags, and test dev-dependencies in the generated CDB; stage only std and already-cached dependency BMIs needed by language toolingcompile_commands.jsonatomically across platforms, preserve last-known-good files and CDB symlinks, and keep normal build/test publication failures non-fatalbuild.mcpp, resolve/install dependencies or toolchains, and update lock/resolution metadataThis is the independently agreed A part from #379. It intentionally does not add JSON/NDJSON,
idesubcommands, snapshots,mcpp.wire,invalidatedBy, or new selector semantics. It does not close the RFC.Core impact
mcpp test; existing list/build/run behavior remains covered by unit and E2E testsrequireCompileDatabaseflag; default build/test behavior remains warning-onlyTest plan
mcpp build --no-color --no-cacheon macOS ARM64mcpp test --no-color: 70 passed, 0 failedtests/e2e/202_configure_only_cdb.sh: syntax-error source, test/dev-dependency flags, workspace fan-out,-p, no build artifacts/cache, publication failure preservation01,18,35,76,77,90,157,159Refs #379
Refs mcpp-community/mcpp-vscode#5