Updates the trace output for type checking to be more consistent like
the rest of trace output.
This PR also includes few changes in the lit tests related to trace
output.
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Co-authored-by: Richard Smith <richard@metafoo.co.uk>
See arena.h for discussion of what canonicalization means in this
context. This is primarily intended to support implementing a memo table
of template instantiations to resolve#2951, but could be useful for
other purposes as well.
Additional changes:
- Pass `VTable` constructor parameters by pointer, to avoid the need to
define `operator==` and `hash_value` for it.
- Clean up the recurring pattern of allocating identical `NamedElement`s
on the stack and heap. Instead we always allocate it on the heap and
pass it by pointer.
- Add `Print()` and `Dump()` to `Bindings` as a debugging convenience.
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Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
This is intended to be used for template instantiation, but for now takes no stance as to what it's cloning.
This is tested by parsing and cloning all of our test files, and checking that the result of converting each AST to proto is the same as the result of cloning and then converting each AST to proto.
Change explorer's handling of witnesses to track them wherever possible. Associated constant support needs witnesses to be available much more pervasively.
The main changes here are:
- `Substitute` now takes a set of bindings covering both `Value`s for `GenericBinding`s and `Witness`es for `ImplBinding`s, and substitutes both.
- Witnesses are now tracked within `ConstraintType`s. The `.Self` type has an `ImplBinding` that self-references from parts of the constraint to other parts of the constraint can use to access the witness for the constraint.
- The constraint type for an `impl` and for a `GenericBinding` are now stored in pre-substituted form, with references to the actual constrained type rather than symbolic references to `.Self`. This results in minor changes in diagnostic text.
Argument deduction still performs substitutions without remapping witnesses.
This avoids the need to make copies of potentially large maps when
the same bindings are used in multiple values, such as when forming
a bound method value.
Prabhat SachdevaandRichard Smith
