Invertible protocols are currently always mangled with `Ri`, followed by
a single letter for each invertible protocol (e.g., `c` and `e` for
`Copyable` and `Escapable`, respectively), followed by the generic
parameter index. However, this requires that we extend the mangling
for any future invertible protocols, which mean they won't be
backward compatible.
Replace this mangling with one that mangles the bit # for the
invertible protocol, e.g., `Ri_` (followed by the generic parameter
index) is bit 0, which is `Copyable`. `Ri0_` (then generic parameter
index) is bit 1, which is `Escapable`. This allows us to round-trip
through mangled names for any invertible protocol, without any
knowledge of what the invertible protocol is, providing forward
compatibility. The same forward compatibility is present in all
metadata and the runtime, allowing us to add more invertible
protocols in the future without updating any of them, and also
allowing backward compatibility.
Only the demangling to human-readable strings maps the bit numbers
back to their names, and there's a fallback printing with just the bit
number when appropriate.
Also generalize the mangling a bit to allow for mangling of invertible
requirements on associated types, e.g., `S.Sequence: ~Copyable`. This
is currently unsupported by the compiler or runtime, but that may
change, and it was easy enough to finish off the mangling work for it.
Introduce metadata and runtime support for describing conformances to
"suppressible" protocols such as `Copyable`. The metadata changes occur
in several different places:
* Context descriptors gain a flag bit to indicate when the type itself has
suppressed one or more suppressible protocols (e.g., it is `~Copyable`).
When the bit is set, the context will have a trailing
`SuppressibleProtocolSet`, a 16-bit bitfield that records one bit for
each suppressed protocol. Types with no suppressed conformances will
leave the bit unset (so the metadata is unchanged), and older runtimes
don't look at the bit, so they will ignore the extra data.
* Generic context descriptors gain a flag bit to indicate when the type
has conditional conformances to suppressible protocols. When set,
there will be trailing metadata containing another
`SuppressibleProtocolSet` (a subset of the one in the main context
descriptor) indicating which suppressible protocols have conditional
conformances, followed by the actual lists of generic requirements
for each of the conditional conformances. Again, if there are no
conditional conformances to suppressible protocols, the bit won't be
set. Old runtimes ignore the bit and any trailing metadata.
* Generic requirements get a new "kind", which provides an ignored
protocol set (another `SuppressibleProtocolSet`) stating which
suppressible protocols should *not* be checked for the subject type
of the generic requirement. For example, this encodes a requirement
like `T: ~Copyable`. These generic requirements can occur anywhere
that there is a generic requirement list, e.g., conditional
conformances and extended existentials. Older runtimes handle unknown
generic requirement kinds by stating that the requirement isn't
satisfied.
Extend the runtime to perform checking of the suppressible
conformances on generic arguments as part of checking generic
requirements. This checking follows the defaults of the language, which
is that every generic argument must conform to each of the suppressible
protocols unless there is an explicit generic requirement that states
which suppressible protocols to ignore. Thus, a generic parameter list
`<T, Y where T: ~Escapable>` will check that `T` is `Copyable` but
not that it is `Escapable`, and check that `U` is both `Copyable` and
`Escapable`. To implement this, we collect the ignored protocol sets
from these suppressed requirements while processing the generic
requirements, then check all of the generic arguments against any
conformances not suppressed.
Answering the actual question "does `X` conform to `Copyable`?" (for
any suppressible protocol) looks at the context descriptor metadata to
answer the question, e.g.,
1. If there is no "suppressed protocol set", then the type conforms.
This covers types that haven't suppressed any conformances, including
all types that predate noncopyable generics.
2. If the suppressed protocol set doesn't contain `Copyable`, then the
type conforms.
3. If the type is generic and has a conditional conformance to
`Copyable`, evaluate the generic requirements for that conditional
conformance to answer whether it conforms.
The procedure above handles the bits of a `SuppressibleProtocolSet`
opaquely, with no mapping down to specific protocols. Therefore, the
same implementation will work even with future suppressible protocols,
including back deployment.
The end result of this is that we can dynamically evaluate conditional
conformances to protocols that depend on conformances to suppressible
protocols.
Implements rdar://123466649.
Extend TypeDecoder with support for inverse requirements, passing them
along to the type builder. Then implement support for inverse
requirements within the AST demangler, which addresses the round-trip
demangling failures we've been seeing.
The runtime and remote inspection facilities still need metadata to
deal with inverse requirements.
Fixes rdar://124564447.
Previously, inverses were only accounted-for in inheritance clauses.
This batch of changes handles inverses appearing in other places, like:
- Protocol compositions
- `some ~Copyable`
- where clauses
with proper attribution of default requirements in their absence.
We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.
Patch produced by
for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done
This avoids us using reserved identifiers as the enum case names of all
our underscored protocols like _ObjectiveCBridgeable. I used the
convention PROTOCOL_WITH_NAME to mirror how the known identifiers work.
Swift SVN r32924
This way they can be used from other projects, like LLDB. The downside
is we now have to make sure the header is included consistently in all
the places we care about, but I think in practice that won't be a problem,
especially not with tests.
rdar://problem/22240127
Swift SVN r31173
...and per DaveA's recommendation, drop the leading zero and reorder, so
people notice that something weird's going on.
No functionality change.
Swift SVN r7267
This doesn't do anything yet, but will be used to record which decls
conform to these protocols when serializing a module.
This introduces a new metaprogramming file, KnownProtocols.def.
Swift SVN r7263
