chore(ci): clean up CH32V307 workflow warnings #382

Context

The Build CH32V307 workflow emitted warnings in GitHub Actions run/job:

• Job: https://github.com/FastLED/fbuild/actions/runs/26870686326/job/79244964744
• Source run: PR Fix ESP32-C2 skeleton SDK install #378 merge ref 5413534c2964257eb904ee3f28ee864093f8e59c
• Workflow input: test-dir=tests/platform/ch32v307, env-name=ch32v307
• Build commands from .github/workflows/template_build.yml:
  • fbuild build tests/platform/ch32v307 -e ch32v307 --quick
  • fbuild build tests/platform/ch32v307 -e ch32v307 --release
• Toolchain reported in the log: riscv-none-elf-gcc 14.2.0
• CH32V core package pinned by fbuild: openwch/arduino_core_ch32 1.0.4

The job completed successfully and produced both quick and release firmware.bin artifacts, but the CH32V307 build commands emitted 104 compiler warning lines. These are 52 warning sites repeated once by the quick build and once by the release build.

Compiler warning breakdown across both passes:

• 30x -Wmissing-field-initializers
  • cores/arduino/ch32/analog.cpp: DAC/ADC init structs
  • cores/arduino/ch32/interrupt.cpp: GPIO/EXTI init structs
• 28x excess elements in struct initializer
  • variants/CH32V30x/CH32V307VCT6/PeripheralPins.c: ADC/DAC/I2C/UART/SPI pin-map terminators
• 20x -Wattributes
  • cores/arduino/ch32/clock.c
  • cores/arduino/ch32/interrupt.cpp
  • system/CH32V30x/USER/ch32v30x_it.c
• 18x -Wcomment
  • system/CH32V30x/SRC/Peripheral/inc/ch32v30x_eth.h: nested comment markers
• 4x -Wunused-variable
  • cores/arduino/ch32/analog.cpp: bank and calibration_value
• 2x -Wsign-compare
  • cores/arduino/ch32/uart.c
• 2x "CH32V30x_D8C" redefined
  • cores/arduino/ch32/ch32_def_build.h defines CH32V30x_D8C
  • fbuild's crates/fbuild-config/assets/boards/json/genericCH32V307VCT6.json also passes -DCH32V30x_D8C via build.extra_flags

The same job also emitted these GitHub warning annotations outside the CH32V firmware build commands:

• setup-soldr: defaulting SOLDR_LINKER=fast ... Set linker: platform-default ... or linker: <value> to silence this warning.
• setup-soldr: build-cache cache payload is 1.12GB before compression (>512.0MB).
• soldr cook prebuilt dependencies, but this job's compile cache recorded 18 miss(es) and 0 hit(s) ... set prebuild-deps: none to skip the unused cook.

Assessment: this is explainable with the current implementation, but should not be treated as the expected final CI state. Most compiler diagnostics come from the pinned upstream OpenWCH Arduino core being compiled under fbuild's CH32V -Wall -Wextra flags. The duplicate CH32V30x_D8C warning is at least partly local, because fbuild's board JSON passes a macro that the OpenWCH startup-selection header also defines. The setup-soldr annotations are expected in the sense that the action is explicitly warning about current cache/linker configuration, but they still produce warning annotations on an otherwise successful board build.

Proposal

Decide and implement a CH32V warning policy so Build CH32V307 no longer emits untracked warnings on successful builds.

Practical options:

• Patch known OpenWCH 1.0.4 issues during Ch32vCores::patch_compatibility, similar to the existing backup-header compatibility patch.
• Scope warning suppressions to third-party OpenWCH core/framework compilation only, so user project code can still surface useful warnings.
• Remove or de-duplicate local board defines that OpenWCH derives internally, starting with CH32V30x_D8C for genericCH32V307VCT6.
• If some upstream diagnostics are intentionally accepted, encode that as an explicit allowlist/count so new warnings are visible.
• Decide whether the setup-soldr annotations should be silenced through explicit workflow inputs/configuration, tracked separately, or kept as intentional annotations.

Acceptance criteria

• Re-running the CH32V307 quick and release CI build no longer emits untracked compiler warning: lines from the OpenWCH core.
• The CH32V30x_D8C redefinition is either fixed or explicitly documented as intentional.
• Any warning suppression is scoped narrowly enough that fbuild does not hide warnings from user/project source files.
• The setup-soldr warning annotations in this job are either removed, intentionally documented, or split into a separate cache/workflow follow-up.
• The issue is closed with evidence from a fresh Build CH32V307 run, including the run URL and warning count.

Open questions

• Should fbuild patch the pinned OpenWCH core on install, or should it keep the downloaded package untouched and apply compile-flag suppressions around third-party sources?
• Should this warning policy apply only to CH32V307 first, or to every CH32V board that consumes openwch/arduino_core_ch32?
• Are the setup-soldr cache/linker annotations in scope for this issue, or should they become a separate CI-cache cleanup issue?

Related issues

No strong duplicate found after searching for CH32V307 warnings, openwch warning, and arduino_core_ch32 in FastLED/fbuild issues.