This change implements the check behavior for the arrow operator.
`ptr->Foo()` is rewritten as `(*ptr).Foo()` and `ptr->(X.y)` is
rewritten as `(*ptr).(X.y)`
On the parsing side, we treat `a.(b)` as a member access whose second
operand is a `ParenExpr` rather than a `MemberName`. A new node category
is added for the union of `MemberName` and `ParenExpr` to support this.
Checking is mostly reusing the same pieces we already have for simple
member access. Compound member access is in most ways a simplified form
of simple member access because it doesn't need to do any lookup.
Add a general substitution mechanism to support substituting symbolic
bindings with their values throughout symbolic constants and, more
specifically, types. This is done by decomposing the constant
instruction into its operands, substituting into the operands, and then
rebuilding the constant value by invoking the constant evaluator.
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Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com>
When a member access names an interface member, perform impl lookup to
find the impl and its corresponding member.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
A couple of minor functional changes here:
- We now always create a `name_ref` for the name referred to by the
right-hand operand of member access. Previously we skipped creating this
instruction if the referenced name was a field, and just created the
field access instruction. This makes our processing of member accesses
and our SemIR representation a bit more uniform.
- We now perform lookup into the type of the left-hand operand if it's
any type with a scope, not just for classes. This means we do lookup
into interface types. However, doing so isn't really useful yet because
it always finds an associated entity that isn't usable by itself. This
changes the diagnostic in
`toolchain/check/testdata/interface/fail_todo_facet_lookup.carbon`.
The member access logic is fairly large, and will be growing with the
addition of impl lookup. Factor it out to separate the logic for dealing
with handling the parse node and updating the node stack from the logic
that checks and builds the member access expression.
CJ Johnson
Richard Smith
