fix(compile): pin TMP/TEMP for compiler subprocess on Windows (#875) by zackees · Pull Request #885 · FastLED/fbuild

zackees · 2026-06-30T18:05:27Z

Problem

compile_source passed Vec::new() as the env to svc.compile(...). zccache's apply_client_env treats Some(env) — even an empty vec — as "client provided full env, clear the daemon's inherited env." So gcc was spawned with a literally empty environment. On Windows that broke compilation on the very first TU: without TMP/TEMP/USERPROFILE/LOCALAPPDATA, the Windows GetTempPathW fallback chain bottoms out at C:\Windows\ (not writable for regular users), and gcc fails with Cannot create temporary file in C:\Windows\: Permission denied before producing a single .o.

This was uncovered by PR #850's tempfile-rooting sweep — the four callers it migrated cover the build-pipeline tempfile creation, not the per-TU compile subprocess's env.

Fix

New helper fbuild_core::subprocess::compile_env_for_build(build_dir) composes the minimum env a Windows compile subprocess needs:

TMPDIR / TMP / TEMP -> fbuild-owned <build_dir>/.compile-tmp (mirrors the link_env_for_build pattern)
PATH, SystemRoot, USERPROFILE, LOCALAPPDATA, APPDATA, PATHEXT, ComSpec forwarded from the host env when present (silently skipped on POSIX where they don't exist).

compile_source derives the build_dir from compile_cwd (with sensible fallbacks) and threads the resulting env into the zccache client call.

Tests

compile_env_for_build_pins_tmp_keys_to_build_dir
compile_env_for_build_is_idempotent

Both pass locally. soldr cargo clippy -p fbuild-core -p fbuild-build --all-targets -- -D warnings clean.

Closes #875

`compile_source` passed `Vec::new()` as the env to `svc.compile(...)`. zccache's `apply_client_env` treats `Some(env)` — even an empty vec — as "client provided full env, clear the daemon's inherited env." So gcc was spawned with a literally empty environment. On Windows that broke compilation on the very first TU: without `TMP`/`TEMP`/`USERPROFILE`/`LOCALAPPDATA`, the Windows `GetTempPathW` fallback chain bottoms out at `C:\Windows\` (not writable for regular users), and gcc fails with `Cannot create temporary file in C:\Windows\: Permission denied` before producing a single `.o`. This is uncovered by PR #850's tempfile-rooting sweep — the four callers it migrated cover the build-pipeline tempfile creation, not the per-TU compile subprocess's env. Fix: add `fbuild_core::subprocess::compile_env_for_build(build_dir)` — the minimum env a Windows compile subprocess needs to find tempfiles + helper binaries (cc1/cc1plus/as) without reintroducing host pollution that would hurt zccache hit rates. Specifically: - TMPDIR / TMP / TEMP -> fbuild-owned `<build_dir>/.compile-tmp` - PATH, SystemRoot, USERPROFILE, LOCALAPPDATA, APPDATA, PATHEXT, ComSpec forwarded from the host env when present (silently skipped on POSIX where they don't exist). `compile_source` derives the build_dir from `compile_cwd` (with sensible fallbacks) and threads the resulting env into the zccache client call. Two regression tests: - `compile_env_for_build_pins_tmp_keys_to_build_dir` - `compile_env_for_build_is_idempotent` Closes #875

coderabbitai · 2026-06-30T18:05:35Z

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crates/fbuild-build/src/compiler.rs
crates/fbuild-core/src/subprocess.rs

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Rolls up the fixes shipped since 2.3.14: - #855 (#883) — drop stale standalone-zccache CI/Docker/docs references after the soldr embedded-zccache transition (soldr#977/#980/#1081) - #865 (#884) — write daemon status via sync write_atomic; unblocks fbuild-daemon unit tests on macOS/Windows by eliminating the block_in_place panic in current-thread tokio runtimes - #875 (#885) — pin TMP/TEMP for compiler subprocess on Windows; ESP32 compile no longer fails with 'Cannot create temporary file in C:\Windows\' on the very first TU - #720 (#886) — record anti-removal policy for dump_usb_ids example - #829 (#887) — stage fbuild._native cdylib during source/editable install so 'from fbuild import ...' works after 'uv pip install -e .' Plus all prior #664 platform_packages audit work, the #826 testing followups, and the build cancellation fix from earlier in the cycle.

…indows (#890) Follow-up to #885 (`fix(compile): pin TMP/TEMP for compiler subprocess on Windows`). With TMP/TEMP env now propagated correctly, gcc's driver finally manages to create its internal spec file — and as soon as it does, the next failure mode surfaces: cc1plus.exe: fatal error: srcmain.cpp: No such file or directory The driver writes args into the spec file using GCC's quoting rules, where `\` is an escape character. So `src\main.cpp` (which `path_arg_for_compile_cwd` returns on Windows because that's how the host OS spells it) is parsed by cc1 as `srcmain.cpp` and fails to open. Fix: convert backslashes to forward slashes for every path arg on Windows. Windows GCC has always accepted both separators for filesystem lookups; forward slashes additionally survive every spec-file / response-file pass unchanged. POSIX hosts pass through unmodified. Repro pre-fix (after #885): bash compile esp32dev --examples Blink → cc1plus.exe: fatal error: srcmain.cpp: No such file or directory Post-fix: clean Blink build in 117 s on Windows. Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

…ESP32 (#3446) (#3447) ## chip-id detection — three-strategy fallback chain (#3446) Previously the autoresearch port detection probed each port with a single 3.0 s esptool `chip-id` attempt using the default DTR/RTS auto- reset. On a CP210x ESP32-WROOM devkit that budget consistently undershoots — the realistic worst case is ~7 s (slow CP210x driver init + ~4 s of esptool SYNC retries + bootloader handshake), so healthy boards were misclassified as "device may not be in bootloader mode" and the entire bring-up gave up before any test could start. New behaviour: - Per-strategy timeout default is 7 s (covers the worst case while keeping a 5-port-all-empty sweep under ~10 s total). - Primary strategy is still `--before default-reset`. - ONLY when the primary attempt actually times out do we escalate to the fallback chain (`--before usb-reset` then `--before no-reset`). "Port open OK but no chip-id produced" stays a fast-path failure — empty ports don't drag the total budget out. - The caller in `_resolve_port` drops its explicit `timeout=3.0` override so it picks up the new default and the fallback chain. Local repro: `bash autoresearch esp32dev` with a CP210x ESP32-wroom on COM11 now resolves to `(esp32) ESP32` on the first attempt instead of `detection failed (esptool timed out after 3.0s)`. ## LegacyClocklessProxy — gate pin 8 on classic ESP32 `SK6812<8, RGB>` instantiation fires FastLED's `_ESPPIN<8, 256, false>::validpin() == false` static_assert because GPIO8 on the classic ESP32 (esp32dev / WROOM) is reserved for SPI flash (D2/HD). Newer ESP32 variants (S2/S3/C2/C3/C5/C6/H2/P4) repurpose GPIO8 and accept it as a valid output pin, and every non- ESP family treats pin 8 as a normal digital — so the gate is the narrow classic-ESP32 exclusion, not a broad change. Mirrors the existing `AUTORESEARCH_LEGACY_SUPPORTS_PIN_22` Teensy gate. Without this the sketch failed at compile time for esp32dev and autoresearch never got past the build phase. ## pyproject.toml — fbuild 2.3.15 pin note + version chase The pin stays at `fbuild==2.3.14` for now (2.3.15 isn't on PyPI yet as of this commit) but the comment history is updated to reflect the Windows compile env + path-separator fixes that landed in FastLED/fbuild#885 and FastLED/fbuild#890. Bump the pin to 2.3.15 in a follow-up once the release workflow publishes. Closes (pending CI): #3446 Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

…path (#912) * feat(cli): fbuild sync + platformio.lock (#618 Phase 1) Implements Phase 1 of the roadmap in #618: fbuild sync reads platformio.ini, classifies every lib_deps entry per env, and writes a deterministic JSON platformio.lock next to the ini. All flags in the issue proposal land: -e <env>, --yes, --locked, --check, --dry-run, --upgrade, --upgrade-package. Multi-env prompt gates whole-project sync; --yes / -e / --check bypass it. # Scope Phase 1 is a full CLI + classification + lockfile-shape ship. Network resolution (GitHub ref -> SHA, PIO registry version -> archive URL, archive sha256) is deferred to Phase 2 per the issue's staged rollout. Every remote entry gets status: "unresolved" with the raw spec + extracted owner/name/ref captured, so Phase 2 will only add fields, never renegotiate the schema. Local sources (symlink://, file://, filesystem paths — absolute POSIX, relative ./ / ../, Windows drive letters) get status: "unlocked" and are recorded verbatim for auditability. # Files Module layout (kept as one focused directory tree, three files, no new crate — respects the monocrate rule): - crates/fbuild-cli/src/sync/mod.rs — orchestrator + SyncArgs + run_sync + prompt logic - crates/fbuild-cli/src/sync/source.rs — SourceType + LockStatus + ClassifiedDep + classify() - crates/fbuild-cli/src/sync/lockfile.rs — Lockfile struct + JSON I/O + LockDiff comparison + atomic write via fbuild_core::fs::write_atomic_sync (from #865) - crates/fbuild-cli/src/cli/sync_cmd.rs — thin CLI adapter - crates/fbuild-cli/src/cli/args.rs — new Commands::Sync variant + KNOWN_SUBCOMMANDS entry - crates/fbuild-cli/src/cli/dispatch.rs — wire the new command - crates/fbuild-cli/src/cli/mod.rs — register sync_cmd - crates/fbuild-cli/src/main.rs — register sync module - docs/sync.md — user-facing docs - docs/CLAUDE.md — index entry # Lockfile schema (v1) - envs sorted alphabetically (BTreeMap) - packages per env sorted by (name, source_type, raw) - generated_at trimmed to seconds (ISO-8601 UTC) - fields with a documented consumer only (no decorative registry metadata — per issue decision) - package records DUPLICATED under each env (per issue decision: auditability > disk size) - read() refuses to load an unrecognized version — schema evolution is versioned # TDD-first — 30+ unit tests written before implementation Written first, then wired up: - crates/fbuild-cli/src/sync/source.rs::tests — 18 tests covering every documented lib_deps shape: - Registry: bare name, name@ver, owner/name@ver, whitespace, raw preservation - GitHub: bare URL, .git suffix, #ref, case-insensitive host - Git+: URL, ref - HTTP archive: .zip, .tar.gz - Local: symlink://, file://, ./relative, ../relative, /posix-abs, C:\ backslash, D:/ forward-slash - phase1_lock_status returns Unlocked for locals, Unresolved for remotes - crates/fbuild-cli/src/sync/lockfile.rs::tests — 10 tests: - Shape smoke - Packages sorted by name - Envs sorted - Local dep -> Unlocked - Registry dep -> Unresolved in Phase 1 - JSON deterministic for same input (regardless of insertion order) - Read/write roundtrip - Version mismatch rejected - compare fresh/stale detection (new dep added, env added, version changed) - JSON ends with newline - crates/fbuild-cli/src/sync/mod.rs::tests — 11 tests: - Missing platformio.ini is error - Single env writes lockfile - --check on missing lock is failed - --check on fresh lock passes - --locked on stale lock returns LockedFailed - --dry-run writes nothing - -e <env> skips multi-env prompt - -e <bad-env> is error - Second run without changes is NoOp - exit_code matrix (Wrote/NoOp/CheckPassed/DryRun=0, CheckFailed=1, LockedFailed=2, UserCancelled=3, Error=4) - skip_multi_env_prompt matrix - ISO date formatter basic + time-of-day # Local verification - `soldr cargo check -p fbuild-cli --all-targets` — clean - `soldr cargo clippy -p fbuild-cli --all-targets -- -D warnings` — clean - `soldr cargo test -p fbuild-cli --no-run` — clean (test binaries build) - `soldr cargo fmt -p fbuild-cli` — no-op Note on test execution: my local environment (soldr silently swallows all stdout/stderr; direct-cargo hits Windows SDK linker env issues that this session has documented at length in #899) prevents me from running the test binary end-to-end today. Every test is pure enough that the compile-clean under -D warnings + the TDD-first authoring order gives strong confidence, and CI will exercise them on Linux. Closes #618 * fix(sync): allow dead_code on Phase 2 hook fields (#618 CI fix) CI on macos/windows failed with clippy `-D dead-code`: - SyncArgs.upgrade + upgrade_package — Phase 2 fields, captured from the CLI now so the argv surface is stable but not yet consumed. - SyncOutcome::Wrote(PathBuf) — payload used by structured callers (tests + future --json subcommand). Clippy doesn't see the tests as consumers. Annotate with #[allow(dead_code)] at the field / enum level with a comment pointing at #618's Phase 2. * fix(compile): rewrite backslashes in source/output args on the no-compile-CWD fallback path Windows PIO builds under `.build/pio/<board>/` don't have a `.fbuild` component upstream of the output path, so `compile_cwd_from_output()` returns None and `compile_source()` fell through to the raw `to_string_lossy()` on the source/output paths. That leaves backslashes intact in argv, which GCC's internal spec-file pass interprets as escape characters: `-c src\sketch\AutoResearchNet.cpp` → cc1plus.exe receives `srcsketchAutoResearchNet.cpp` → "fatal error: srcsketchAutoResearchNet.cpp: No such file or directory". Symptomatically identical to the fix that landed in #875 / #885 for the compile-CWD arm; the fallback arm was missed. Mirror the same `replace('\', "/")` guard so both paths agree on Windows. Bump workspace version 2.3.15 → 2.3.16. Repro: `bash compile esp32dev --examples AutoResearch` from a FastLED checkout on Windows failed at the first .cpp compile with `srcsketchAutoResearchNet.cpp` / `srcsketchAutoResearchBle.cpp` etc. After this fix, the compile completes end-to-end. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

zackees merged commit 8bab4db into main Jun 30, 2026
81 of 93 checks passed

zackees deleted the fix/875-windows-tempfile-empty-env branch June 30, 2026 18:05

zackees mentioned this pull request Jun 30, 2026

chore: bump version to 2.3.15 #888

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zackees mentioned this pull request Jun 30, 2026

fix(compile): force / in path args so cc1 spec-file pass works on Windows #890

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zackees mentioned this pull request Jun 30, 2026

fix(autoresearch): chip-id probe fallback chain + classic-ESP32 pin 8 gate (#3446) FastLED/FastLED#3447

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fastled-project-sync Bot added this to FastLED Tracker Jun 30, 2026

This was referenced Jul 1, 2026

dylint(ban_std_pathbuf): unstuck migration + catch manual backslash-to-slash rewrite anti-pattern #911

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fix(compile): rewrite backslashes on the PIO no-compile-CWD fallback path #912

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fastled-project-sync Bot moved this to Triage in FastLED Tracker Jul 1, 2026

This was referenced Jul 1, 2026

feat(dylints): ban manual backslash-to-slash rewrite; migrate all sites to NormalizedPath::display_slash() (#911) #914

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perf(build): framework libs (~150s) recompiled per project; core cache never hydrates #952

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fix(compile): pin TMP/TEMP for compiler subprocess on Windows (#875)#885

fix(compile): pin TMP/TEMP for compiler subprocess on Windows (#875)#885
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zackees commented Jun 30, 2026

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zackees commented Jun 30, 2026

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