Related to discussion on #738, but also trying to standardize handling of everything and make placement of token spellings (`AND "and"`) consistently in lexer.lpp.
I could have gone the other direction, removing the list of things in lexer.lpp, but this feels like it does more to use the compiler to detect skew between lexer.lpp and parser.ypp.
`Pattern` is intended to pilot some changes I would like to apply to all our sum types:
- The alternatives are expressed as derived classes rather than members of a `std::variant`.
- The alternatives are classes in the [style guide sense](https://google.github.io/styleguide/cppguide.html#Structs_vs._Classes), meaning they can have invariants, but can't have public data members.
- Creating an object is expressed using a constructor rather than a factory function.
- Accessing an alternative is expressed as a cast (using LLVM's RTTI system) rather than `std::get` or a `Get` method.
Co-authored-by: Jon Meow <46229924+jonmeow@users.noreply.github.com>
This is intended to:
- Standardize use of line_num (and highlight where no line_num is available).
- Standardize indications of runtime/compilation errors.
- Make it incrementally easier to write new errors.
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
Jon Meow
Geoff RomerandJon Meow
Jeremy G. SiekandJon Meow