Stop creating ImplicitlyUnwrappedOptional<T> so that we can remove it
from the type system.
Enable the code that generates disjunctions for Optional<T> and
rewrites expressions based on the original declared type being 'T!'.
Most of the changes supporting this were previously merged to master,
but some things were difficult to merge to master without actually
removing IUOs from the type system:
- Dynamic member lookup and dynamic subscripting
- Changes to ensure the bridging peephole still works
Past commits have attempted to retain as much fidelity with how we
were printing things as possible. There are some cases where we still
are not printing things the same way:
- In diagnostics we will print '?' rather than '!'
- Some SourceKit and Code Completion output where we print a Type
rather than Decl.
Things like module printing via swift-ide-test attempt to print '!'
any place that we now have Optional types that were declared as IUOs.
There are some diagnostics regressions related to the fact that we can
no longer "look through" IUOs. For the same reason some output and
functionality changes in Code Completion. I have an idea of how we can
restore these, and have opened a bug to investigate doing so.
There are some small source compatibility breaks that result from
this change:
- Results of dynamic lookup that are themselves declared IUO can in
rare circumstances be inferred differently. This shows up in
test/ClangImporter/objc_parse.swift, where we have
var optStr = obj.nsstringProperty
Rather than inferring optStr to be 'String!?', we now infer this to
be 'String??', which is in line with the expectations of SE-0054.
The fact that we were only inferring the outermost IUO to be an
Optional in Swift 4 was a result of the incomplete implementation of
SE-0054 as opposed to a particular design. This should rarely cause
problems since in the common-case of actually using the property rather
than just assigning it to a value with inferred type, we will behave
the same way.
- Overloading functions with inout parameters strictly by a difference
in optionality (i.e. Optional<T> vs. ImplicitlyUnwrappedOptional<T>)
will result in an error rather than the diagnostic that was added
in Swift 4.1.
- Any place where '!' was being used where it wasn't supposed to be
allowed by SE-0054 will now treat the '!' as if it were '?'.
Swift 4.1 generates warnings for these saying that putting '!'
in that location is deprecated. These locations include for example
typealiases or any place where '!' is nested in another type like
`Int!?` or `[Int!]`.
This commit effectively means ImplicitlyUnwrappedOptional<T> is no
longer part of the type system, although I haven't actually removed
all of the code dealing with it yet.
ImplicitlyUnwrappedOptional<T> is is dead, long live implicitly
unwrapped Optional<T>!
Resolves rdar://problem/33272674.
DeclContexts as they exist today are "over aligned" when compared to
their natural alignment boundary and therefore they can easily cause
adjacent padding when dropped into the middle of objects via C++
inheritance, or when the clang importer prefaces Swift AST allocations
with a pointer to the corresponding clang AST node.
With this change, we move DeclContexts to the front of the memory layout
of AST nodes. This allows us to restore natural alignment, save memory,
and as a side effect: more easily avoid "over alignment" in the future
because DeclContexts now only need to directly track which AST node
hierarchy they're associated with, not specific AST nodes within each
hierarchy.
Finally, as a word of caution, after this change one can no longer
assume that AST nodes safely convert back and forth with "void*". For
example, WitnessTableEntry needed fixing with this change.
This expression node is only used when applying the results of
expression type checking. It initially appears above the function
reference that returns an optional that needs to be unwrapped, and
then when dealing with function application we remove this and insert
a node to force-unwrap the result of the function application.
1) Remove SWIFT_INLINE_BITS boilerplate. Now that we're not using anonymous/transparent unions, we don't need the
SWIFT_BITFIELD_BITS macro.
2) Refine the the bitfield size check to better support templated bitfields.
3) Refine the SIL templated bitfields to not be prematurely "full".
Also, give each class hierarchy at least 8 bits for the 'Kind' field.
In practice, no class hierarchy has more than 256 nodes, so this
optimizees code generation to make isa/dyn_cast faster.
Inline bitfields are a common design pattern in LLVM and derived
projects, but the associated boilerplate can be demotivating and
brittle. This new header makes it easier to define and use inline
bitfields in Swift.
This also reorders some fields for better code generation.
Integer and Floating literals are aware of their negation but
do not store the sign in the text of the value. Retrieve the
sign bit and properly interpolate the text of the literal value
with it to distinguish negative and positive literals.
just for pointer identity.
The current technique for deciding whether that's the case is *extremely*
hacky and need to be replaced with an attribute, but I'm reluctant to
take that on so late in the schedule. The hack is terrible but not too
hard to back out in the future. Anyone who names a method like this just
to get the magic behavior knows well that they are not on the side of
righteousness.
rdar://33265254
To remove some callers of 'is<InOutType>' after Sema, start using what will soon be a structural invariant - the only expressions that can possibly have 'inout' type are semantically InOut expressions.
ground work for the syntactic bridging peephole.
- Pass source and dest formal types to the bridging routines in addition
to the dest lowered type. The dest lowered type is still necessary
in order to handle non-standard abstraction patterns for the dest type.
- Change bridging abstraction patterns to store bridged formal types
instead of the formal type.
- Improve how SIL type lowering deals with import-as-member patterns.
- Fix some AST bugs where inadequate information was being stored in
various expressions.
- Introduce the idea of a converting SGFContext and use it to regularize
the existing id-as-Any conversion peephole.
- Improve various places in SILGen to emit directly into contexts.
We neglected to set it on one path (a scalar-to-tuple conversion path currently only taken by subscript applications). Change TupleShuffleExpr's constructor to take it as an argument so this mistake is harder to make in the future. Fixes SR-5264 | rdar://problem/32860988.
Situations where there is a contextual RawRepresentable type is
used incorrectly would produce `<Type>(rawValue: )` fix-it only
in cases where neither or both sides of the expression are optional.
Let's fix that by adding a fix-it for optional to contextual raw
value type conversion.
Resolves: rdar://problem/32431736
Now that preCheckExpression() can handle more cases, we can
eliminate a special case where sometimes we would make
DeclRefExprs instead of TypeExprs for references to generic
types.
It's particularly likely someone will try to type `\(foo)`, which looks like a string interpolation segment, outside of a string literal, so give that case a special diagnostic. Fixes rdar://problem/32315365.
This introduces a few unfortunate things because the syntax is awkward.
In particular, the period and following token in \.[a], \.? and \.! are
token sequences that don't appear anywhere else in Swift, and so need
special handling. This is somewhat compounded by \foo.bar.baz possibly
being \(foo).bar.baz or \(foo.bar).baz (parens around the type), and,
furthermore, needing to distinguish \Foo?.bar from \Foo.?bar.
rdar://problem/31724243
