There's no hook to surface exceptions to MicroPython so they're basically useless?

I can imagine people would want to use

try
{
  //do C++
}
catch(const std::exception&)
{
  mp_raise_msg(&mp_type_RuntimeError, "oops your C++ code threw an exception");
}

Not sure what would happen in such case with this PR, but probably won't work as expected, so I'd say this should be optional?

I'd say this should be optional?

Probably, I have no idea what I'm doing and why nosys.specs seems to be the only way I can disable the exception handling stuff here.

All I know for sure is that our USER_C_MODULES builds (a lotta modules to be fair) bloat up and overflow the flash app size when these features are enabled, and we don't ever use C++ style exception handling.

I guess ideally this would be possible to disable per module? In fact I wonder if I've ever actually tried just adding this to our USER_C_MODULES cmake files...

It would probably also be nice if builds didn't build at all when User Flash overlaps the App, but that's been quite tricky. See this saga: #8761

Right now it'll happily build a MicroPython port where the user filesystem simply overwrites the end of the app, corrupts it and renders the Pico unbootable until it's reflashed.

I wonder if I've ever actually tried just adding this to our USER_C_MODULES cmake files...

Ah, I though you tried that first then made it into a PR because it worked :)

Ah, I though you tried that first then made it into a PR because it worked :)

I've only ever added it directly to the CMakeLists.txt. Turns out there's no real need for it to be there, other than as a hint/helper/optional thing to prevent future C++ module users running into the same trouble I did- not thinking to put it into our downstream cmake files has caused me untold pain over the last few years. 🤦

pimoroni/pimoroni-pico#968

I guess it would make more sense as a snippet in examples/usercmodule/cppexample/micropython.cmake with appropriate comments.

Though I'm still not sure why nano.specs is needed and how that might conflict with nosys.specs used elsewhere.

I guess it would make more sense as a snippet in examples/usercmodule/cppexample/micropython.cmake with appropriate comments.

Yes, that would make sense. If you want to change this PR to do that, I'd be happy to merge it.

Though I'm still not sure why nano.specs is needed and how that might conflict with nosys.specs used elsewhere.

I also have no idea about this.

I have re-targeted this but I'm still not sure it's suitable since:

1. I don't know why it works
2. The commented-out snippet isn't run in CI, so we wont know if/when it breaks

But at least, for now, it's here for posterity.

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.42%. Comparing base (ee10360) to head (65913d8).

@@           Coverage Diff           @@
##           master   #11143   +/-   ##
=======================================
  Coverage   98.42%   98.42%           
=======================================
  Files         161      161           
  Lines       21253    21253           
=======================================
  Hits        20919    20919           
  Misses        334      334           

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