Compile fails after upgrading to v4.0(undefined reference to `_Z9setupMenuv')

[davetcc]

Set the default option back to source and generated code together, anything else is not supported by regular Arduino build system.

Discussed in #376

^{Originally posted by prowong July 7, 2023}
All things work fine in v3.1. But after upgrading to v4.0, I just created a very simple menu with only two items, and the compilation error message is as follows. I've tried a full clean install with the same result. On the other hand, when opening the old version of the project in v4.0 and generating code, the compilation is successful. Any suggestions?

d:/program files/arduinodata/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.1.0-gcc10.3-e5f9fec/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: C:\Users\Patrick\AppData\Local\Temp\arduino\sketches\3797C9C34B5C4AC64A24480549BFE714\sketch\VNC008.ino.cpp.o:(.text.setup+0x0): undefined reference to _Z9setupMenuv'
collect2.exe: error: ld returned 1 exit status`

[davetcc]

Should you hit this issue, simply set the build location property to all in one location (select root menu item in tree). we'll look at other options like a local library (which I think Arduino supports later.

[davetcc]

Unfortunately, there are no easy answers for regular Arduino build, it does not support local libraries in the lib directory, and it does not support subfolders, so for Arduino, everything must be in one directory.

PlatformIO, cmake and probably mbed - you can use any directory/storage option you like.
Arduino CLI/IDE - there must be not be a generated subfolder.