feat(esp): add production size-optimization flags to all 11 ESP starter configs

[zackees]

Summary

ESP32-family and ESP8266 starter configs all linked at ~600 KB Blink-class binaries because the default Arduino-ESP32 build carries:

• build_type = debug + -Og (no optimization)
• CORE_DEBUG_LEVEL=5 + ESP_LOG_VERBOSE (every log string compiled in)
• full libstdc++ exception machinery (no -fno-exceptions / -fno-rtti)
• no per-function/data sections + no -Wl,--gc-sections, so the linker drops nothing it doesn't have to

This PR adds a heavily commented [build_type=release / build_flags / build_unflags] block to each ESP env.

Verified savings (from FastLED's own esp32dev CI, FastLED/FastLED#3268):

Sketch	Before	After	Delta
Blink	631100 B	408136 B	-223 KB (-35%)

The block is fully commented for new users: "comment out (or set build_type = debug) when you need verbose logs / exception decoding while developing." Each file points to FastLED/FastLED#3268 for the underlying investigation.

Files updated (all 11 ESP starters)

• platformio.esp32c2.ini
• platformio.esp32c3.ini
• platformio.esp32c5.ini (preserves existing PARLIO ISR flags)
• platformio.esp32c6.ini (preserves existing PARLIO ISR flags)
• platformio.esp32dev.ini
• platformio.esp32h2.ini (preserves existing PARLIO ISR flags)
• platformio.esp32p4.ini (preserves existing PARLIO ISR flags)
• platformio.esp32s2.ini
• platformio.esp32s3.ini (preserves existing exception_decoder filter)
• platformio.esp8266.ini (NONOS SDK — no CORE_DEBUG_LEVEL macro)
• platformio.seeed_xiao_esp32s3.ini

Test plan

• Inspected each ESP starter file in platforms/ — flags are appropriate for the SDK each targets (ESP-IDF for esp32-family, NONOS for esp8266).
• Preserved existing PARLIO ISR / exception_decoder configurations.
• CI / sample builds against each board to confirm sizes track the FastLED PR's numbers.

🤖 Generated with Claude Code

Summary by CodeRabbit

Release Notes

• Chores
  • Updated build configurations for all supported platforms (ESP32 variants, ESP8266, and Seeed Xiao ESP32-S3) with optimized compiler and linker flags for release builds, including size optimization, debug output removal, and link-time optimization.

[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: e06fbfb0-965b-489e-966a-15f0332c4ff9

📥 Commits

Reviewing files that changed from the base of the PR and between 58faf18 and b2e0b6f.

📒 Files selected for processing (11)

• platforms/platformio.esp32c2.ini
• platforms/platformio.esp32c3.ini
• platforms/platformio.esp32c5.ini
• platforms/platformio.esp32c6.ini
• platforms/platformio.esp32dev.ini
• platforms/platformio.esp32h2.ini
• platforms/platformio.esp32p4.ini
• platforms/platformio.esp32s2.ini
• platforms/platformio.esp32s3.ini
• platforms/platformio.esp8266.ini
• platforms/platformio.seeed_xiao_esp32s3.ini

---

📝 Walkthrough

Walkthrough

All ten ESP32 and ESP8266 PlatformIO environment INI files receive a uniform size-optimization release build configuration: build_type = release, compiler/linker flags disabling debug logs, C++ exceptions, RTTI, and unwind tables while enabling -Os, LTO, function/data sectioning, and linker GC-sections, plus build_unflags removing -Og and -g. Targets that already had PARLIO ISR defines retain those alongside the new flags.

Changes

Size Optimization Release Build Config

Layer / File(s)	Summary
Targets with no prior build_flags platforms/platformio.esp32c2.ini, platforms/platformio.esp32c3.ini, platforms/platformio.esp32dev.ini, platforms/platformio.esp32s2.ini, platforms/platformio.esp8266.ini, platforms/platformio.seeed_xiao_esp32s3.ini, platforms/platformio.esp32s3.ini	Adds build_type = release, build_flags for -Os, LTO, sectioning, disabled exceptions/RTTI/unwind tables, and build_unflags removing -Og/-g to environments that had no prior flag overrides. ESP32-S3 additionally reformats monitor_filters to list default and esp32_exception_decoder explicitly.
Targets extending PARLIO build_flags platforms/platformio.esp32c5.ini, platforms/platformio.esp32c6.ini, platforms/platformio.esp32h2.ini, platforms/platformio.esp32p4.ini	Expands the existing PARLIO ISR define-only build_flags block with the same release/size-optimization configuration, keeping the PARLIO -DCONFIG_* defines alongside the new flags.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related issues

• fbuild: ESP32 board build_flags / build_unflags aren't propagating from ci/boards.py FastLED#3298: This PR applies the same set of size-optimization flags (-Os, -fno-exceptions, -fno-rtti, -fno-unwind-tables, -ffunction-sections, -fdata-sections, build_unflags = -Og -g) to PlatformIO INI files that the linked issue describes propagating through a separate compile pipeline.
• Add ESP32 PARLIO-capable boards (C5, C6, H2, P4) with required ISR-IRAM flags #9: This PR extends size-optimization build flags to esp32c5, esp32c6, esp32h2, and esp32p4 environments that already contained the PARLIO-specific ISR configuration introduced in that issue.

Poem

🐇 Hop, hop, the bunny trims the code so lean,
-Os and LTO make the binaries clean.
No RTTI, no exceptions, no debug to weigh,
Sections get collected, dead code swept away.
Release flags bloom in every .ini file,
The rabbit grins — smaller builds in style! 🌸

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/esp-release-size-flags

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}