We noticed that a project failed to build with prepared overloads enabled,
but built successfully with prepared overloads disabled.
It turns out that the code clearly should never have been accepted in the
first place, because the type checker was making an arbitrary choice between
two nominal type declarations with the same name.
Further inspection revealed this was because of a FIXME added in 2013 which
was far too broad. Tighten up the logic here to only disambiguate if at least
one of the two declarations is a type alias, and it has the same underlying
type as the other one. A choice between unrelated nominal type declarations
should always be ambiguous.
This still isn't perfect, because we might have two generic type aliases
that are referenced in both solutions with different substitution maps,
in which case we will still erroneously pick the first one. But this
is better than the old logic, at least.
Fixes rdar://165863775.
There is no debug output from the `CompareDeclSpecializationRequest`
because the flag that enables it is not passed down from the primary
constraint system.
Package the flag into `performanceHacksEnabled()` method on
`ConstraintSystem` and start using it to wrap all of the hacks
in constraint generator and the solver.
Escaping solver-allocated types into a nested allocation arena is
problematic since we can e.g lazily compute the `ContextSubMap` for a
`NominalOrBoundGenericNominalType`, which is then destroyed when we
exit the nested arena. Ensure we don't pass any types with type
variables or placeholders to `typesSatisfyConstraint`.
rdar://152763265
Arguments that were already pack expansions were being wrapped in a
second layer--preventing some would-be unambiguous overloads from
resolving. This adds a check to avoid doing that.
Today ParenType is used:
1. As the type of ParenExpr
2. As the payload type of an unlabeled single
associated value enum case (and the type of
ParenPattern).
3. As the type for an `(X)` TypeRepr
For 1, this leads to some odd behavior, e.g the
type of `(5.0 * 5).squareRoot()` is `(Double)`. For
2, we should be checking the arity of the enum case
constructor parameters and the presence of
ParenPattern respectively. Eventually we ought to
consider replacing Paren/TuplePattern with a
PatternList node, similar to ArgumentList.
3 is one case where it could be argued that there's
some utility in preserving the sugar of the type
that the user wrote. However it's really not clear
to me that this is particularly desirable since a
bunch of diagnostic logic is already stripping
ParenTypes. In cases where we care about how the
type was written in source, we really ought to be
consulting the TypeRepr.
Previously, the constraint solver would first attempt member lookup that
excluded members from transitively imported modules. If there were no viable
candidates, it would perform a second lookup that included the previously
excluded members, treating any candidates as unviable. This meant that if the
member reference did resolve to one of the unviable candidates the resulting
AST would be broken, which could cause unwanted knock-on diagnostics.
Now, members from transitively imported modules are always returned in the set
of viable candidates. However, scoring will always prioritize candidates from
directly imported modules over members from transitive imports. This solves the
ambiguities that `MemberImportVisibility` is designed to prevent. If the only
viable candidates are from transitively imported modules, though, then the
reference will be resolved successfully and diagnosed later in
`MiscDiagnostics.cpp`. The resulting AST will not contain any errors, which
ensures that necessary access levels can be computed correctly for the imports
suggested by `MemberImportVisibility` fix-its.
Resolves rdar://126637855.
Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)
We have two places where `CompareDeclSpecializationRequest` is used:
- A performance optimization that compares two generic overloads;
- Solution ranking that checks all of the selected overloads against
another solution.
The former can allow missing conformances and shouldn't prevent
the solver from checking overloads that differ on `Sendable`
(because there is no information about what is passed as arguments)
but the latter, since it has a solution, should prefer Sendable
overloads over non-Sendable ones if possible
(i.e. `init<T: Sendable>(_: T)` is a subtype of `init<T>(_: T)`).
If one of the choices is variadic generic, let's use `matchCallArguments`
to find argument/parameter mappings and form pack expansions for arguments
when necessary.
Resolves: rdar://112029630
Ignore conversion score increases during code completion to make sure we don't filter solutions that might start receiving the best score based on a choice of the code completion token.
This is phase-1 of switching from llvm::Optional to std::optional in the
next rebranch. llvm::Optional was removed from upstream LLVM, so we need
to migrate off rather soon. On Darwin, std::optional, and llvm::Optional
have the same layout, so we don't need to be as concerned about ABI
beyond the name mangling. `llvm::Optional` is only returned from one
function in
```
getStandardTypeSubst(StringRef TypeName,
bool allowConcurrencyManglings);
```
It's the return value, so it should not impact the mangling of the
function, and the layout is the same as `std::optional`, so it should be
mostly okay. This function doesn't appear to have users, and the ABI was
already broken 2 years ago for concurrency and no one seemed to notice
so this should be "okay".
I'm doing the migration incrementally so that folks working on main can
cherry-pick back to the release/5.9 branch. Once 5.9 is done and locked
away, then we can go through and finish the replacement. Since `None`
and `Optional` show up in contexts where they are not `llvm::None` and
`llvm::Optional`, I'm preparing the work now by going through and
removing the namespace unwrapping and making the `llvm` namespace
explicit. This should make it fairly mechanical to go through and
replace llvm::Optional with std::optional, and llvm::None with
std::nullopt. It's also a change that can be brought onto the
release/5.9 with minimal impact. This should be an NFC change.
`openType` didn't need a locator before it was simply replacing generic
parameters with corresponding type variables but now, with opening of
pack expansions types, a locator is needed for pack expansion variables.
`getValue` -> `value`
`getValueOr` -> `value_or`
`hasValue` -> `has_value`
`map` -> `transform`
The old API will be deprecated in the rebranch.
To avoid merge conflicts, use the new API already in the main branch.
rdar://102362022
These will never appear in the source language, but can arise
after substitution when the original type is a tuple type with
a pack expansion type.
Two examples:
- original type: (Int, T...), substitution T := {}
- original type: (T...), substitution T := {Int}
We need to model these correctly to maintain invariants.
Callers that previously used to rely on TupleType::get()
returning a ParenType now explicitly check for the one-element
case instead.
