Zero Sized Strings

[Kronos3]

In the spec https://nasa.github.io/fpp/fpp-spec.html#Type-Names_String-Type-Names it says that string sizes must be in the range [0, 2^31), the wiki agrees with this.

The implementation doesn't allow 0:

fpp/compiler/lib/src/main/scala/analysis/CheckSemantics/FinalizeTypeDefs.scala

Lines 222 to 226 in 35ac2c9

	if (size > 0 && size <= Int.MaxValue) Right(t)
	else {
	val loc = Locations.get(id)
	Left(SemanticError.InvalidStringSize(loc, size))
	}

Not really sure what the implications of string size 0 are but presumably it could be useful if the string size configuredConstant use case is used and you want to disable a field? We should test to make sure compilation works with string size 0 without any warnings.

[bocchino]

Good catch! We should also test that in the framework, the Fw::StringBase classes are OK with having a zero capacity.