It turns out that the bitpacked Commons struct is actually fairly expensive because the CPU needs to apply bitmasks to fetch the IsToken and Presence flag. We've got padding space available, so we might as well properly align these boolean flags.
Also on a source level, replace a couple of bit-restricted unsigned fields by their representing type (e.g. SyntaxKind).
Finally, we can pull out the common bits to RawSyntax and have the Bits union only contain the token- or layout-specific fields.
This also allows us to initialise these fields in the constructor's initialiser list (instead of in the initialiser body).
Lastly, change copyToArenaIfNecessary to work on a char *& and length, which allows us to initialise leading/trailing trivia/token text in the initialiser list and adjust if necessary later.
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C++ to SwiftSyntax, but superceded by the CLibParseActions.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.
To represent a type with code completion.
type? '.'? <code-completion-token>
This is "parser only" node which is not exposed to SwiftSyntax.
Using this, defer to set the parsed type to code-completion callbacks.
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.
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.
* Generate libSyntax API
This patch removes the hand-rolled libSyntax API and replaces it with an
API that's entirely automatically generated. This means the API is
guaranteed to be internally stylistically and functionally consistent.
