This implements #826, I think covering everything important there.
Regarding ReturnTypeContext, I broke that out because it started feeling like a significant number of args to be passing around, and I think this makes the association inside type checking clearer.
Co-authored-by: Geoff Romer <gromer@google.com>
The code is pretty intertwined: having the AST be truly mutable means (to me) changing parser.ypp to return non-const values, but then the way things are passed around between objects should be non-const (particularly an issue with lists), which then creates issues with construction of lists in the TypeChecker, which then TypeChecker needs to mostly be non-const.
Due to the difficulties in breaking this apart, whereas I'd previously considering refactoring accessor naming in the same PR, I've largely avoided doing so. The intent is then that this PR focuses mainly on const -> non-const AST behavior.
call_main moves out of interpreter.cpp so that interpreter.cpp can receive a fully const AST.
Revives BisonWrap because this seems a reasonable use of it (avoiding the need to have an std::optional or pointer for Alternative, both of which I thought could be unclear about the intent).
I'm seeing if I can upstream thundergolfer/bazel-mypy-integration#43, but we can also point at my fork for the time being.
This should resolve conflicts with mypy treating imports as non-hermetic, creating inconsistent behavior if packages are/aren't installed locally.
With this, only main.cpp instantiates an arena. Maybe we'll want to split that up more later (e.g., so that the runtime interpreter uses its own arena), but given the intent to have type-checking update the AST, I thought this was a reasonable approach for now in order to avoid ownership complexities.
Fixes#769
Also apply it to the list of tokens. This way there's no need for "sort order" comments.
This was a side-effect of me trying to merge in api/impl/library/package, and thinking "why am I doing this manually?"
Co-authored-by: Geoff Romer <gromer@google.com>
Doesn't add much logic, only takes advantage of parser structure for the ordering enforcement.
Note import_nonexistent tests should probably fail, but writing import tests needs a chain of functionality, and I figured I'd just start adding some to validate the syntax (not adding existent imports because that'd require multi-file structure).
This is based on discussion on #732: that we should probably parse the invalid whitespace, then reject it as part of string validation, rather than having different parses. I worry the question of "how is this parsed" may lead to subtly unexpected results if we aren't consistent, so I'm switching the logic from the lexer to the unescape library (and also adjusting the list of rejected whitespace).
Along with #789 this addresses most of #769 although global_arena is still a TODO (that's widespread and overlaps with other changes so I wanted to do it after these are in).
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.
Note this makes a few cases where the Statement was optional explicit (Block, If, Sequence). I do add a few CHECKs around where statements were optional and assumed but unverified.
I switch TypeCheckStmt to not take an optional Statement because I think it makes the call sites clearer in behavior. It's also a smaller change than the converse, because taking an optional Statement means the returned statement would also need to be optional. Arguably a wrapper for optional statements could be added, but this still seems cleaner to me, and there aren't that many cases of an optional statement.
Co-authored-by: Geoff Romer <gromer@google.com>
Sorry about the big change, this is hard to split. ParenContents is used by both, templated, and expects the same pointer type. While I could duplicate ParenContents with some ExpressionParenContents or PatternParenContents, that seems a little kludgy versus a single large change handling both. The worst of it is that Expression is already pretty sweeping, Pattern is really just incrementally adding.
That said, I believe this includes a couple fixes I found with incorrect use of dyn_cast in typecheck.cpp (checked nullptr at the wrong step in 2 code locations). There's also a missing `*` in member.cpp this caught. I adjust passing of expressions for Return due to nullness (I felt adding another constructor was the best solution).
I add a `.Release()` to BisonWrap due to things like `$3.first` needing some way to work through BIsonWrap. I felt this was better than `operator->`, but feel free to comment if you prefer the other path (`.Release()` conveniently lets me do pair unwrapping, so it felt a better solution).
I do add a TODO to think about better Ptr-to-Ptr cast<> support too, though, as that doesn't work cleanly with LLVM's infra. But so far it seems to only come up in one spot, so I'm not prioritizing it.
Per https://github.com/bazelbuild/rules_cc this still isn't necessary. There's no build-time enforcement, so usage is inconsistent/incorrect. Rather than letting this linger, remove it pending Bazel tooling enforcing it.
This opens up a path for switching `int line_num` to a `Location loc`, which I want to do for tracking filenames of code. But I don't think we should have a default constructor on `Location` to avoid mistakes, and switching FunctionDefinition to an arena alloc seems more consistent anyways.
It was in my mind to add String in order to support libraries in `package`. `print` is added in order to have a String go to stdout. I've tried to do `print` in a way that won't be too hard to add other printable types, but it's probably also somewhat optional here -- that is, if desired, I could remove it. But it was a lot easier to doublecheck `\n` behavior with it, and I suspect it'll be helpful in other tests if it supports more value types.
On the side, this also fixes dereferencing in Pattern/Expression Print() calls, which I was noticing printing pointers instead of values. This may be another argument for moving away from passing pointers, since this seems to be a difficult-to-catch error.
Co-authored-by: Geoff Romer <gromer@google.com>
This creates a ReturnExpression. A separate change should enforce that an implicit return of `()` is only allowed in functions that have an implicit return type of `()`, and I think the structure taken here should ease that.
`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>
Geoff Romer
Jon Meow
Jeremy G. SiekandJon Meow