This does some more work to the run_clang_tidy.py wrapper script, and runs an example pass.
"again" because it's really the proto fuzzer changes that broke it, it had been working before.
"mostly" because there's still an issue within the proto fuzzer that it can't find "port/protobuf.h", i.e. https://github.com/google/libprotobuf-mutator/tree/master/port, but I'm still hesitant to add an include path there.
Previously we used an expression in some places and a `Witness` values in others. The eventual goal is to make `Witness` values behave like other symbolic values such as `NominalClassType`, but the first step is to consistently treat them like values rather than expressions.
No functionality change intended.
This renames `Witness` to `ImplWitness` and adds a new form, `SymbolicWitness`, that holds an expression by which a witness can be computed. A common base class `Witness` is provided.
We form the new kind of witness when evaluation of a witness expression fails because the witness is not in scope, as happens when evaluating a subexpression such as a type expression in isolation, and retry evaluation in the larger context when the interpreter performs type instantiation when running the code.
This allows us to properly handle compile-time evaluation of constructs involving witness table lookups when the witness can be statically determined. The intent is that we will eventually also form symbolic witness table references when impl selection finds a non-final witness, in order to support specialization.
Simplify `NominalClassValue`: it can now always store a witness map rather than either a witness map or a witness-or-witness-expression map.
Jon Ross-Perkins
Richard Smith
pmqtt