semantic_analysis.txt

semantic analysis
- [error] [done] auto string not allowed as struct field
- [error] [done] only one auto string param or return allowed per function
- [error] [done] array of auto strings is not allowed
- [error] [done] custom data type must be in the list of structs or enums
- [warning] [done] custom enum or struct not referenced in any function or any other custom type
- [error] [done] duplicate service IDs
- [error] [done] duplicate function IDs (in same service)
- [error] [done] duplicate enum field IDs (in same enum)
- [error] [done] duplicate service names
- [error] [done] duplicate function names (in same service)
- [error] [done] duplicate struct/enum names
- [error] [done] duplicate enum field names (in same enum)
- [error] [done] duplicate struct field names (in same struct)

# Decision:
# 1. Trivial function parameters (int, bool, float, etc) are by value
# 2. Structs function parameters are also passed by value
#   - string and array struct members are passed by value as etl::string and etl::array
# 3. Non-trivial function parameters are always by reference
#   - arrays are passed as span
#   - strings are passed as string_view
# 4. Function returns are by default by value
#   - For strings and arrays and structs, this could result in a large object on the stack and an additional copy of data.
#     However, returning things by reference means that the returned values must exist outside the scope of the function.
#     This is more efficient, but less intuitive
#   - At a later stage it may become possible to annotate a function to make it return something by reference
# 5. The implication of returning things by value is that it is not possible to return an auto string
# 6. The implication of passing structs by value is that it structs cannot have an auto string member