#2569 added PrintAsID to //common/ostream.h, but given it's
explorer-specific behavior, I don't think it's the right home for it.
Noticed this while pondering better ostream interfaces.
Defines methods into `TraceStream` for adding line prefixes. Instead of
directly using string literals.
Example usage,
```
trace_stream_->Start() << "declaring ... " << ... ;
```
will result in,
```
->> declaring ...
```
Per #257, we should be treating unformedness as all-or-nothing, rather than being a per-field or per-array-element property. Previously we initialized an array with no explicit initializer as containing a sequence of uninitialized values, but that led to crashes when attempting to access those values, as the checks for reading an uninitialized value only expected values to be uninitialized at the top level.
Also, we had existing tests that attempt to store to an element of an uninitialized array. We now detect that and treat it as UB during evaluation, rather than crashing due to trying to perform field access into an uninitialized value.
Finally, many of these problems can be detected statically, but the resolve_unformed pass wasn't catching them because it missed a few expression and declaration forms. Support for those cases has been added too. This causes the pass to recurse more often, and in particular our existing recursion test started hitting a stack overflow after this, so resolve_unformed now uses `RunWithExtraStack`. In passing, remove the need to explicitly tell `RunWithExtraStack` the return type, and infer it as the return type of the callable instead.
Removes `__continuation`, `__await`, and `__run`.
In part here, the discussion was that while the feature had been useful for validating the early explorer design, it's no longer needed for that role as the explorer is now quite robust. Continuations have been experimental and, at this point, don't have an owner pushing to a proposal.
The triggering factor is that, as we push to address fuzzer issues, I ran into a crash bug in this code; basically, `fn Main() -> i32 { __await; return 0; }`. When I mentioned this, the reaction seemed to trend towards removal of the feature.
Add support for user-defined assignment, as well as compound assignment and increment, following the design direction in pending proposal #2511.
Some of this isn't fully testable yet: because explorer doesn't properly support `impl` specialization, the blanket `impl`s in the prelude prevent types from customizing assignment.
Add basic support for `match_first` declarations to explorer, as described in https://github.com/carbon-language/carbon-lang/blob/trunk/docs/design/generics/details.md#prioritization-rule. The concrete syntax here is not yet approved, so `match_first` is renamed to `__match_first` for now, but the semantics are necessary to implement other approved features in explorer so we're intentionally getting a little ahead of the design here.
Addresses comments from this discussion: https://github.com/carbon-language/carbon-lang/pull/2460#discussion_r1046444433
Features:
* Move subtyping logic from Interpreter to TypeChecker, exposing subtyping as a series of access to `.base`.
* Excludes function parameter conversion, which is still done in ::Convert due to parameters conversion being handled differently.
Changes:
* Add new `class BaseAccessExpression : public MemberAccessExpression`, allowing rewrites
* Handle `BaseAccessExpression` expression type in Interpreter
* Move subtyping logic to `TypeChecker::ImplicitlyConvert`
In particular, this means that a type can implement `ImplicitAs(Type)` and have values of that type behave like types.
This implies that `()` and `{}` are no longer types. They are now values whose type is the result of converting `()` or `{}` to type `Type`, as has been discussed recently and seems to be the supported direction. This fixes various cases where these types were previously mishandled.
Instead of forming a `SymbolicWitness` that contains an `Expression` when we can't directly resolve a witness to an `impl`, form different kinds of `Witness` values for the various situations:
- A `BindingWitness` witnesses that a type implements a constraint by reference to an `ImplBinding`.
- A `ConstraintWitness` witnesses that a type implements a constraint by reference to witnesses for each of the impl constraints within the constraint.
- A `ConstraintImplWitness` witnesses that a type implements a constraint by reference to a larger constraint which contains that constraint as an impl constraint.
Remove `SymbolicWitness` values and `InstantiateImpl` expressions, which are now unused. In order to remove the final usage of `SymbolicWitness`, I fixed a TODO to give `Self` the proper type within an interface declaration. I don't think this is an observable change.
No functional change intended.
* Replay changes from pre-force-push mixin branch
* Base MixinPseudoType off of the new InterfaceType
* Add more test cases.
Also removed an unnecessary check that would have already been
handled by the parser.
* WIP detect member clashes during mixing mixins
* Implement fuzzer changes
* Implement member name clash check when mixing mixins
* Modify parser and lexer for experimental mixin feature
* Add comments
* Update explorer/testdata/mixin/simple-mix-in-mixin.carbon
Co-authored-by: josh11b <josh11b@users.noreply.github.com>
* Update explorer/testdata/mixin/use-mixin-method-in-class-method.carbon
Co-authored-by: josh11b <josh11b@users.noreply.github.com>
* Make code review changes
Co-authored-by: josh11b <josh11b@users.noreply.github.com>
- Added detection of unformed usage with `return var`, control-flow statements and member access.
- Refactored the work flow: made flow facts a class and moved operations of flow facts into the class.
- Added, cleaned and renamed test cases. Some test cases for the dynamic unformed check were suppressed by the static check. They are now added back.
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
- An introprocedural forward analysis that checks the may-be-formed states on local variables.
- Returns compilation error on usage of must-be-unformed variables.
- Implemented as a pass of `ASTNode` traversal.
- Currently supports detection of: function parameter, return expression and rhs of assign.
Jon Ross-Perkins
Prabhat Sachdeva
josh11b
Richard Smith
Adrien Leravat
pmqtt
Darshal Shettyandjosh11b
Zenong ZhangandJon Ross-Perkins
