The merged component copied every library into ONE interleaved tree and
then exported EVERY directory that held a file. A library's private
internals therefore sat on the global -I and hijacked #includes issued by
other libraries, by the arduino-esp32 core and by ESP-IDF itself. Each
incident was patched by adding a name to _SHADOW_STD_HEADERS — chasing
symptoms, since the denylist grows with every library that ships a
generically-named internal header (three landed yesterday alone:
FastLED's platforms/stub/Arduino.h, its fl/stl/asio/http/http_parser.h,
and earlier LovyanGFX's lgfx/internal/limits.h).
Adopt arduino-cli's model instead — the resolver every other Velxio board
family already delegates to. It shares one global -I list too, but adds
exactly ONE directory per library: <lib>/src for the recursive layout,
<lib> for the flat legacy one, never a subdirectory; utility/ stays
private to its owner. arduino-esp32 does the same as an IDF component.
- Each library is copied into its own subtree of the component, so two
libraries shipping the same relative path no longer collapse into one
silently-picked copy.
- INCLUDE_DIRS is one root per library, in resolution order. Internals
stay copied and reachable through file-relative includes.
- Legacy-layout utility/ dirs go in PRIV_INCLUDE_DIRS.
- Root-level header collisions (the only shadowing still possible) are
logged the way the Arduino IDE reports them, instead of being silent.
- The transitive scan now walks only the library just copied.
One component is deliberate: a component per library would swap this
failure mode for REQUIRES-order shadowing (IDF exports component includes
as plain -I, never -isystem) plus IDF component-name collisions, and buys
no caching ccache does not already provide.
Verified against the real FastLED+U8g2 project WITH the two denylist
entries removed: green, byte-identical firmware size. The 3-library
SSD1306+GFX+BusIO corpus is green too. VELXIO_PER_LIB_ROOTS=0 restores
the legacy layout; the mode is folded into the build-variant hash so the
two can never share a configured build dir.
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