default source installs to fast no-LTO profile

[zackees]

Summary

• Keep source installs on the fast Rust dev profile (no LTO) by default.
• Add the supported PEP 517 override: pip install . --config-settings fbuild-profile=release.
• Preserve FBUILD_BUILD_RELEASE=1 as an environment override.
• Guarantee ESP32 linker section garbage collection even when SDK linker flags replace the JSON fallback.
• Document the profile behavior and include the backend adapter in source distributions.

Why

pip install . -- --release is not a supported pip-to-PEP-517 forwarding mechanism. The backend adapter translates the standard --config-settings value into the existing setup.py profile switch.

No-LTO builds already compile with -ffunction-sections and -fdata-sections across the platform JSON configurations. The ESP32 linker now adds -Wl,--gc-sections when SDK-provided linker flags omit it, preserving section-level dead-code elimination for compact quick builds.

Measurements

Using tests/platform/esp32dev, ESP32 Arduino core 3.3.7, and xtensa-esp-elf-gcc 14.2.0:

Profile	Clean build	Flash	RAM
Quick / no LTO	17.5s	295,244 bytes	100,521 bytes
Release / full LTO	20.2s	295,244 bytes	100,521 bytes

For this fixture, no-LTO is 2.7 seconds (13%) faster with no measured size penalty after section garbage collection. The result is fixture-specific; broader boards should be benchmarked separately.

Validation

• uv build --wheel --no-build-isolation: passed; produced dist/fbuild-2.5.2-cp313-cp313-win_amd64.whl.
• PEP 517 profile translation and setuptools metadata hook: passed.
• soldr rustfmt --check crates/fbuild-build-esp/src/esp32/esp32_linker.rs: passed.
• Static audit: all platform JSON configurations contain function/data section splitting and --gc-sections.
• git diff --check: passed.

The wheel’s first native build took about 12.1 minutes because the Cargo target was cold; subsequent installs reuse the pinned incremental target.

Summary by CodeRabbit

• New Features

  • Added support for selecting fast development or optimized release builds through standard package installation settings.
  • Source distributions now include the required build support for these installation options.

• Bug Fixes

  • Ensured section garbage collection is enabled when using SDK-provided linker flags, reducing unnecessary firmware content.

• Documentation

  • Clarified installation commands, release-build configuration, and unsupported argument-passing behavior.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 8601d091-1a0e-46a7-88fe-2445b144e620

📥 Commits

Reviewing files that changed from the base of the PR and between debc996 and 0824754.

📒 Files selected for processing (6)

• MANIFEST.in
• build_backend.py
• crates/fbuild-build-esp/src/esp32/esp32_linker.rs
• docs/getting-started/README.md
• pyproject.toml
• setup.py

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📝 Walkthrough

Walkthrough

Adds a PEP 517 backend adapter supporting fbuild profile settings, configures packaging to use it, documents release builds, and preserves ESP32 linker section garbage collection when SDK flags are provided.

Changes

PEP 517 build backend

Layer / File(s)	Summary
Profile-aware backend adapter build_backend.py	Normalizes and validates fbuild-profile and fbuild-release, temporarily sets FBUILD_BUILD_RELEASE, and delegates wheel, editable, sdist, metadata, and requirement operations to setuptools.
Backend wiring and release documentation pyproject.toml, MANIFEST.in, setup.py, docs/getting-started/README.md	Selects the custom backend, packages it, documents the supported release setting, and describes the corresponding build behavior.

ESP32 linker flags

Layer / File(s)	Summary
Preserve section garbage collection crates/fbuild-build-esp/src/esp32/esp32_linker.rs	Ensures -Wl,--gc-sections is present when SDK linker flags are used and tests that path.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Pip
  participant build_backend
  participant Setuptools
  participant setup_py
  Pip->>build_backend: Pass fbuild profile settings
  build_backend->>build_backend: Validate settings
  build_backend->>setup_py: Set FBUILD_BUILD_RELEASE temporarily
  build_backend->>Setuptools: Delegate build operation
  Setuptools-->>Pip: Return artifact or metadata

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch agent/no-lto-pip-gc-sections

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