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.
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.
`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>
- Switch code to llvm::raw_ostream as part of standardizing output forms.
- Preferring llvm::raw_ostream over std::ostream because other tooling code should be expected to rely on llvm more closely, and an overall preference towards library consistency.
- There are a couple spots in syntax/ that still use std streams, but I'd prefer to take a separate PR to see how best to address those.
- std::boolalpha doesn't work with llvm, so I've implemented equivalent in a couple places (not enough that it felt like worth making a helper function).
- Implement Print(ostream) as consistently as we can, as an instance member.
- This facilitates the use of the common/ostream.h template to provide operators.
- Preferring this approach so that Print is easily accessible via gdb, per suggestion on #executable-semantics.
- Switch code currently calling `type->Print(ostream)` to instead do `ostream << *type`.
- Remove the unused `PrintTypeEnv`, nothing used it and the declaration didn't match the definition.
Note this makes some structural choices that I'm not sure how popular they'll be... Most notably, I could remove `DeclarationKind` because I'm using `std::visit` and `Declaration::Visitor` in reality. I could go to `switch(tag())` instead, but I'm wondering if this approach will be well received for the separation of ownership. Alternatively, I could move `Declaration` around so that it actually implements the things like `TopLevel` -- I did feel weird with the old structure of typecheck.cpp implementing members of declaration.h, though.
Making Values const allows us to separate the actual mutations (search for "*&" in this change) from places where the Value is effectively passed by-value.
* global variables
* implemented type checking of global variable, added test case
* added a comment
* improvements based on Dave's suggestions
* improvements based on Jon's suggestions
* added test cases about global variable ordering
* improve abstraction for AssocList, fix bug in optional else
* add flag for tracing output, clean up code for output
* turned off tracing by default, updated goldens, removed two examples that use pointers, shouldn't have been there yet
This change creates an unpleasant amount of boilerplate where `Declaration` is declared, in exchange for being able to—very pleasantly—treat it as a simple value that composes with other values everywhere it is used. Applying this technique broadly will pay off in code comprehensibility; once it has been done for all things being new'd, pointers disappear and references are only needed as an idiomatic approximation of inout. The unpleasant code grows only when new polymorphic operations are added, and then only a bit, and is an idiom whose details can readily be ignored once in place. The pleasant code pervades the codebase.
Too bad we don't have existential types in C++ ;-)
* [executable semantics] class-ify Declaration
NFC (no functional change).
Proof of concept that we can simplify code by replacing unions with safer, more
regular types. Hand-rolled existentials (type-erasing CoW wrappers) are a follow-on
step that will further simplify usage.
Began adding `const` where possible, and replacing `std::string*` with
`std::string`. Most `const`s can disappear as we replace reference semantics
with value semantics, but in the meantime it's an important step in the right
direction.
Notes versus what jsiek wrote:
- This adopts Bazel for building.
- System-local versions of bison/flex are used. I found https://github.com/jmillikin/rules_bison, but those print a lot of warnings (things like -Wsign-compare IIRC) which makes builds hard to read. Plus I think the underlying bison_cc_library rule didn't work, so this would really only get a hermetic bison/flex build (helpful, but didn't seem worth more time).
- I'm adding in a .bazeliskrc to push a somewhat more standard choice of bazel versions. I noticed I was getting unstable versions by default, possible Google-specific, but seemed good to include.
- The `-lpthread` kludge.
- Turn all of the examples into golden tests.
- Including adding a golden test rule.
- Fixed various style guide issues. For example:
- Fixing function names to be CamelCase instead of snake_case (https://google.github.io/styleguide/cppguide.html#Function_Names)
- Removed exception use (https://google.github.io/styleguide/cppguide.html#Exceptions)
- File name fixes (https://github.com/carbon-language/carbon-lang/blob/trunk/docs/project/cpp_style_guide.md#file-names)
- Dropped `using` of `std` names -- I believe this is preferred (maybe we should be explicit about this in the Carbon style guide)
- Switched `enum` uses to `enum class` for ease-of-identification.
- Spent some time breaking out files to hopefully be easier to read/edit pieces, and understand relations between structs.
- Added `code requires` to `syntax.ypp` to address include issues
Possibly other things -- but the fundamental structure is, I believe, unchanged. I put in the golden tests pretty early to ensure I wasn't mutating output/results.
Jon Meow
Geoff Romer
Jeremy G. Siek
Dave Abrahams
Jeremy G. SiekandJon Meow