The ASTs for functions which aren't definitions may not be fully
typechecked or well-formed, so: avoid looking at them.
This fixes at least one assertion failure seen while building a project
with coverage, and is probably good for some substantial compile-time
improvements with coverage enabled.
rdar://39069115
Previous to this change, the initial inspection of the -{enable,disable}-batch-mode
flag was made separate from the subsequent overriding by -wmo; this in turn meant
that the driver might decide it's "in batch mode" in one place (in particular,
when judging whether to ignore the -num-threads flag) and "in wmo mode" elsewhere
(when judging whether to emit one or multiple outputs, which depends on the
-num-threads flag).
Divergence between these two views caused the driver to effectively drop
the -num-threads flag even when overriding batch mode with wmo; since xcode
assumes that passing -wmo -num-threads _will_ cause multiple outputs, this
in turn caused linking to fail since the expected output files were not found.
Code may end up indirectly using a witness table for a Clang-imported type by inlining code that used the conformance from another module, in which case we need to ensure we have a local definition at hand in the inlining module so we can have something to link against independently. This needs to be fixed from both sides:
- During serialization, serialize not only witness tables from the current module, but from Clang-imported modules too
- During deserialization, when the SILLinker walks a loaded module, ensure that all shared conformances get deserialized, including those from ApplyInsts and inherited/associated type protocol requirements.
Fixes rdar://problem/38687726.
Also, make ExistentialLayout non-self-referential, by moving that logic to the
point where it is used. The construction of the one-element-ArrayRef is so cheap
that it doesn't need to be cached.
Many uses of conditional conformance to protocols with super-protocols
are for wrappers, where the conformances to those super-protocols
usually ends up using weaker bounds, such as:
struct MyWrapper<Wrapped: Sequence> {}
extension Wrapped: Sequence {} // Wrapped: Sequence
extension Wrapped: Collection where Wrapped: Collection {} // *
extension Wrapped: BidirectionalCollection where Wrapped: BidirectionalCollection {}
If this code was instead written:
struct MyWrapper<Wrapped: Sequence> {}
extension Wrapped: Sequence {} // Wrapped: Sequence
extension Wrapped: BidirectionalCollection where Wrapped: BidirectionalCollection {}
Inferring a Collection conformance would have to mean
extension Wrapped: Collection where Wrapped: BidirectionalCollection {}
which is unnecessarily strong.
It is a breaking change to change a protocol bound, and so we're
thinking we'd prefer that the compiler didn't magic up that incorrect
conformance. It also only is a small change (and the compiler even
suggests it, with a fixit) to explicitly get the implying behaviour:
declare the conformance explicitly.
extension Wrapped: Collection, BidirectionalCollection where Wrapped: BidirectionalCollection {}
Fixes rdar://problem/36499373.
We need to be able to find which conformances need to be
declared/constructed without forcing extensions to be completely
validated. This is important for both SR-6569 and
rdar://problem/36499373. The former due to the source-level recursion,
and the latter because implied conformances weren't always
constructed (but are needed for good diagnostics).
They weren't always constructed because:
1. ConformanceLookupTable's updateLookupTable on an early stage (before
implied conformances are found) triggers extension
validation *before* constructing any conformances, but *after*
updating the stage state
2. extension validation validates the conditional requirements
3. validating the conditional requirements requires setting up generic
signatures
4. setting up generic signatures forces the types conformances and so
ends up in updateLookupTable on the same nominal again, skipping over
the earlier stages that are complete/in progress
5. we expand the conformances that are implied by all the conformances we
know about... But we don't know any, because we haven't finished the
first updateLookupTable.
This breaks the loop at step 2: we instead do the minimal work needed to
know what conformances an extension (might) declare, which is connect
the extension to a type, and then resolve the inherited TypeReprs to
Types.
With the previous changes, validating a property while
type checking its initializer is no longer a fatal error.
This means we don't have to do anything special when
validating typo correction candidates, so we can get rid
of the TypoCorrectionResolver. This means there is now
only one subclass of LazyResolver, the TypeChecker itself.
We can use the existing logic for checking recursion in
declaration validation. This eliminates some bogus
diagnostics and allows some weird logic to be removed
from typo correction.
Type of elements contained by field offsets vector can be adjusted
to 32-bit integers (from being pointer sized) to safe space in the
binary since segment size is limited to 4 GB.
Resolves: rdar://problem/36560486
