Implementation is as follows: In `preCheckExpression` try to
detect if there is `T(literal)` call in the AST, replace it with
implicit `literal as T`, while trying to form type-checked AST,
after constraint solving, restore source information and drop
unnecessary coercion expression.
Resolves: rdar://problem/17088188
Resolves: rdar://problem/39120081
Resolves: rdar://problem/23672697
Resolves: rdar://problem/40379985
Instead of mixing flags between type-checker and constraint solver, let's
move the ones which are useful in constraint system there. Doing
so allows for `solveForExpression` to be moved from `TypeChecker` to
`ConstraintSystem` which consolidates solver logic.
It also allows to set these flags as part of constraint generation/solving,
which is sometimes important.
Replace the last (and most obscure) use of the poor “use ‘?’ or ‘!’” diagnostic with the
new, more explanatory version that provides separate notes with Fix-Its for coalescing or
force-unwrapping the value.
Finishes rdar://problem/42081852.
Introduce a new fix kind into the constraint solver to cover unwrapping the base
of a member access so we can refer to the a member of the unwrapped base.
Wire this fix kind to the just-added diagnostic that suggests either the
chaining ‘?’ or the force-unwrap ‘!’ via separate, descriptive Fix-Its.
Example:
error: value of optional type 'X?' must be unwrapped to refer to member 'f' of wrapped base type 'X'
let _: Int = x.f()
^
note: chain the optional using '?' to access member 'f' only for non-'nil' base values
let _: Int = x.f()
^
?
note: force-unwrap using '!' to abort execution if the optional value contains 'nil'
let _: Int = x.f()
^
!
Before this, we would sometimes get a Fix-It for just ‘?’ and sometimes get a Fix-It for the
coalescing ‘??’, neither of which is likely to be right.
More work on rdar://problem/42081852.
When we determine that an optional value needs to be unwrapped to make
an expression type check, use notes to provide several different
Fix-It options (with descriptions) rather than always pushing users
toward '!'. Specifically, the errors + Fix-Its now looks like this:
error: value of optional type 'X?' must be unwrapped to a value of
type 'X'
f(x)
^
note: coalesce using '??' to provide a default when the optional
value contains 'nil'
f(x)
^
?? <#default value#>
note: force-unwrap using '!' to abort execution if the optional
value contains 'nil'
f(x)
^
!
Fixes rdar://problem/42081852.
While trying to emit implicit load expression make sure that it's
done in a way where force/paren expression is always top level,
that leads to better fix-its and, in case of forcing, more compact
SIL by intermediate optional container.
Resolves: [SR-8150](https://bugs.swift.org/browse/SR-8150) / rdar://problem/41725207
`finish{Array,Dictionary}Expr` currently invoke `cs.cacheExprTypes` after building their semantic exprs, which in a nested collection expression, immediately undoes the type changes done by this peephole, leading to crashes due to inconsistencies in the AST later. rdar://problem/41040820
The storage kind has been replaced with three separate "impl kinds",
one for each of the basic access kinds (read, write, and read/write).
This makes it far easier to mix-and-match implementations of different
accessors, as well as subtleties like implementing both a setter
and an independent read/write operation.
AccessStrategy has become a bit more explicit about how exactly the
access should be implemented. For example, the accessor-based kinds
now carry the exact accessor intended to be used. Also, I've shifted
responsibilities slightly between AccessStrategy and AccessSemantics
so that AccessSemantics::Ordinary can be used except in the sorts of
semantic-bypasses that accessor synthesis wants. This requires
knowing the correct DC of the access when computing the access strategy;
the upshot is that SILGenFunction now needs a DC.
Accessor synthesis has been reworked so that only the declarations are
built immediately; body synthesis can be safely delayed out of the main
decl-checking path. This caused a large number of ramifications,
especially for lazy properties, and greatly inflated the size of this
patch. That is... really regrettable. The impetus for changing this
was necessity: I needed to rework accessor synthesis to end its reliance
on distinctions like Stored vs. StoredWithTrivialAccessors, and those
fixes were exposing serious re-entrancy problems, and fixing that... well.
Breaking the fixes apart at this point would be a serious endeavor.
This is correct because it's the apparent rule used by CSSimplify:
value-to-autoclosure conversion is considered if and only if the
input type is not an autoclosure function type.
The real solution to this problem is that @autoclosure should be tracked
as a bit on the parameter type instead of as a bit on function types.
Slava has a PR leading towards that (https://github.com/apple/swift/pull/10094),
but it causes a source-compatibility problem when forwarding autoclosures.
You really shouldn't be able to forward autoclosures, but that's an
issue for the core team to resolve, and in the meantime there's this bug.
Fixes rdar://41219750.
There are other parts of CSApply that attempt to peephole transform ArrayExprs (particularly bridging, which tries to turn `[x, y, ...] as T` into `[x as T, y as T, ...]`) and expect the elements to have already been rvalue-d. Fixes rdar://problem/40859007.
Refactor the interface to return a bit vector. Along the way, fix up
the callers and remove some dead usages of the defaults information
that were copied and pasted around Sema.
If the base value was 'self', we were allowing a reference to a
non-required initializer, because you're allowed to do this inside
another initializer.
But if you're in a static method, 'self.init' should obey the same
restrictions as 'foo.init' for any other metatype value 'foo'.
The isImplicit flag on an UnresolvedMemberExpr was not carried over to the CallExpr node generated after type checking, which caused later stages of compilation to try to use invalid SourceLocs. This change correctly propagates the flag.
Disallow implicit conversion or arguments from Array, String, and
InOut (formed by &) to pointer types if the argument is for an
@autoclosure parameter.
These conversions were really only intended to be used for C/ObjC
interop, and in some contexts like autoclosures they are not safe.
Fixes: rdar://problem/31538995
This is modeled in constraint system in a way
that when member type is resolved by `resolveOverload`
it would take r-value type of the element at
specified index, but if it's a type variable it
could still be bound to l-value later, so r-value
result has to be enforced by coercion if necessary.
Resolves: rdar://problem/39931475
Rather than ASTContext-allocating ConcreteDeclRef’s storage when there is a
non-empty substitution map, put the SubstitutionMap directly in the
ConcreteDeclRef. Simplify the various interfaces along the way.
Replace two prominent uses of SubstitutionList, in ConcreteDeclRef and
Witness, with SubstitutionMap. Deal with the myriad places where we
now have substitution maps and need substitution lists (or vice versa)
caused by this change.
Overall, removes ~50 explicit uses of SubstitutionList (of ~400).
This code dates back to the dark ages when forming substitutions
was something only the constraint solver could do.
Now that findNamedWitnessImpl() returns a ConcreteDeclRef instead
of a ValueDecl, we don't have to build a whole constraint system
and type check it just to form substitutions for the call.
