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Add a native compatibility shim for build_type=debug and debug_build_flags #36
Description
Parent: #34
Problem
PlatformIO's debug mode is a declarative feature, not just a pile of user flags. build_type = debug changes the build mode, strips existing optimization/debug flags, adds __PLATFORMIO_BUILD_DEBUG__, and applies debug_build_flags (defaulting to -Og -g2 -ggdb2 when not overridden).
PlatformIO source evidence
- Build mode is derived from
build_type/ special targets:.cache/platformio-core/platformio/builder/tools/piobuild.py:47-57 - Debug mode is activated during dependency processing:
.cache/platformio-core/platformio/builder/tools/piobuild.py:118-128 - Debug configuration removes prior
-O*/-g*, adds__PLATFORMIO_BUILD_DEBUG__, and mergesdebug_build_flags:.cache/platformio-core/platformio/builder/tools/piomisc.py:91-127 - PlatformIO has regression tests for default and custom debug flags:
.cache/platformio-core/tests/commands/test_run.py:200-248
Current fbuild state
BuildProfileonly hasReleaseandQuick:crates/fbuild-core/src/lib.rs:55-69- The native build pipeline only reads
build_flags/build_src_flags:crates/fbuild-build/src/pipeline.rs:106-111
Requested change
Design and implement a native compatibility shim for the declarative debug subset:
- parse
build_type = debug - parse
debug_build_flags - apply PlatformIO-like debug semantics to effective compile/link flags
- add
__PLATFORMIO_BUILD_DEBUG__ - decide how this maps onto fbuild's internal profile model (
debugprofile vs reworked profile abstraction)
Scope notes
- This issue is about the declarative debug subset only
- It should not pull in arbitrary
extra_scripts/ full SCons behavior build_type = testcan be left out of the first implementation if that reduces risk, but the support boundary should be explicit
Acceptance criteria
- A native fbuild build reproduces PlatformIO-like debug flag semantics for representative cases
- Default debug flags match PlatformIO expectations unless explicitly overridden
- Existing optimization/debug flags are cleaned up before new debug flags are applied
- Regression tests cover both default and custom
debug_build_flags
Activity
zackees commentedon Apr 17, 2026
Closing this as completed on current main.
The native debug compatibility shim is already implemented:
PlatformIOConfigparsesbuild_typeanddebug_build_flagsincrates/fbuild-config/src/ini_parser.rsBuildContext::new()applies the debug path incrates/fbuild-build/src/pipeline.rswhenbuild_type == "debug"apply_debug_build_type()strips prior-O*/-g*, adds-D__PLATFORMIO_BUILD_DEBUG__, and appliesdebug_build_flagsCurrent regression coverage also matches the issue intent:
cargo test -p fbuild-config test_get_build_type_reads_debugcargo test -p fbuild-config test_get_debug_build_flags -- --nocapturecargo test -p fbuild-build test_apply_debug_build_type_replaces_opt_flags_and_adds_debug_definecargo test -p fbuild-build test_debug_mode_then_build_unflags_can_remove_debug_flags_againThose all pass on current
main, so the requested declarative debug subset is in place.