Now that main/CMakeLists.txt globs every *.cpp/*.c into SRCS (commit
27c9a28 — needed so multi-file Arduino projects link), sketch.ino.cpp
is compiled as its own translation unit. The template main.cpp's
`#include "sketch.ino.cpp"` is left over from when SRCS only named
main.cpp — back then we had to pull the user code into main.cpp's TU
to get it compiled at all.
With the glob in place, keeping the include re-defines setup() and
loop() in main.cpp's TU AND in sketch.ino.cpp.obj, so the linker dies
with "multiple definition of `setup'". Replace the include with a
forward declaration and let the linker resolve setup()/loop() from
sketch.ino.cpp.obj. Matches arduino-cli's per-file compile + auto-link
model, and frees pure-C++ multi-file sketches to put helper TUs in
their own .cpp files without textual-include hacks.
Repro: robot-desktop-eyes after the glob fix (#13 rebuild) — compile
got past resolve+compile and into link, where multi-def of setup()
would have appeared on the next attempt. This commit closes the loop.
21791a8237