These APIs are quite convoluted. The checks for var_decl need to be performed in
just the right order. The is a consequence of complexity in the SIL
representation itself, not a problem with the APIs.
It is common for code to accidentally call a less-complete form of the API. It
is essential that they be defined in a central location, and the we get the same
answer whether we start with an Instruction, Argument, or Value. The primary
public interface should always check for debug_value users. The varDecl property
is actually an implementation detail.
It is questionable whether a function like findVarDecl() that returns a basic
property of SIL and does not require arguments should be a property instead. It
is a function to hint that it may scan the use-list, which is not something
we normally want SIL properties to do. Use-lists can grow linearly in function
size. But, again, this is a natural result of the SIL representation and needs
to be considered an implementation detail.
Add a note explaining that dependence on closure captures is not
supported. Otherwise, the diagnostics are very confusing:
"it depends on a closure capture; this is not yet supported"
* rename `ScopedInstruction.endOperands` -> `scopeEndingOperands`
* let them behave the same way. For `load_borrow` there was a difference because `endOperands` didn't consider branches to re-borrow phis.
Allow a dependency on a local [read] access scope to be transfered to the
caller's [modify] access.
Fixes rdar://149560133 (Invalid lifetime dependence error when
trying to return Span from an inout argument)
Add support for returnValue phis (e.g. to return an Optional .some or .none).
Fixes rdar://149397018 (Wrapping non escapable in an Optional
(or any copy lifetime wrapper) is an escape)
If the method is a default witness methods (`selfType` != nil) it has generic self type.
In this case the generic self parameter is at depth 0 and the actual generic parameters of the substitution map are at depth + 1, e.g:
```
@convention(witness_method: P) <τ_0_0><τ_1_0 where τ_0_0 : GenClass<τ_1_0>.T>
^ ^
self params of substitution map at depth + 1
```
* move it from the SIL to the AST module (where it belongs)
* change the signature of `diagnose` from `diagnose(location, .some_error)` to `diagnose(.some_error, at: location)`
* add an overload to allow passing a `SIL.Location` directly to `diagnose`
* add a `Diagnostic : Error` utility struct which allows throwing a `Diagnostic`
Store specialize witness tables in a separate lookup table in the module. This allows that for a normal conformance there can exist the original _and_ a specialized witness table.
Also, add a boolean property `isSpecialized` to `WitnessTable` which indicates whether the witness table is specialized or not.
When performing a dynamic cast to an existential type that satisfies
(Metatype)Sendable, it is unsafe to allow isolated conformances of any
kind to satisfy protocol requirements for the existential. Identify
these cases and mark the corresponding cast instructions with a new flag,
`[prohibit_isolated_conformances]` that will be used to indicate to the
runtime that isolated conformances need to be rejected.
