It was originally designed for faster trasmission of syntax trees from
C++ to SwiftSyntax, but superceded by the CLibParseActions. There's no
deserializer for it anymore, so let's just remove it.
By convention, most structs and classes in the Swift compiler include a `dump()` method which prints debugging information. This method is meant to be called only from the debugger, but this means they’re often unused and may be eliminated from optimized binaries. On the other hand, some parts of the compiler call `dump()` methods directly despite them being intended as a pure debugging aid. clang supports attributes which can be used to avoid these problems, but they’re used very inconsistently across the compiler.
This commit adds `SWIFT_DEBUG_DUMP` and `SWIFT_DEBUG_DUMPER(<name>(<params>))` macros to declare `dump()` methods with the appropriate set of attributes and adopts this macro throughout the frontend. It does not pervasively adopt this macro in SILGen, SILOptimizer, or IRGen; these components use `dump()` methods in a different way where they’re frequently called from debugging code. Nor does it adopt it in runtime components like swiftRuntime and swiftReflection, because I’m a bit worried about size.
Despite the large number of files and lines affected, this change is NFC.
This silences the instances of the warning from Visual Studio about not all
codepaths returning a value. This makes the output more readable and less
likely to lose useful warnings. NFC.
We cannot use unowned strings for token texts of incrementally parsed
syntax trees since the source buffer to which reused nodes refer will
have been freed for reused nodes. Always copying the token text whenever
OwnedString is passed is too expensive. A reference counted copy of the
string allows us to keep the token's string alive across incremental
parses while eliminating unnecessary copies.
For ScalarTraits, a buffer was always created on the heap to which the
scalar string value was written just to be copied to the output buffer
again. In case the value already exists in a memory buffer it is way
cheaper to avoid the heap allocation and copy it straight to the output
buffer.
The existing libSyntax infrastructure uses external python
dictionaries to share logic between C++ and Swift implementations.
This patch teaches trivia kinds to adapt to this infrastructure
as well.
