The order of evaluation for arguments is underspecified in the language
specification. It is permissible to evluate right to left, resulting in the use
after the move of the OwnedPtr. This happens in practice on Windows. Alter the
construction to avoid this.
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.
Add an option to the lexer to go back and get a list of "full"
tokens, which include their leading and trailing trivia, which
we can index into from SourceLocs in the current AST.
This starts the Syntax sublibrary, which will support structured
editing APIs. Some skeleton support and basic implementations are
in place for types and generics in the grammar. Yes, it's slightly
redundant with what we have right now. lib/AST conflates syntax
and semantics in the same place(s); this is a first step in changing
that to separate the two concepts for clarity and also to get closer
to incremental parsing and type-checking. The goal is to eventually
extract all of the syntactic information from lib/AST and change that
to be more of a semantic/symbolic model.
Stub out a Semantics manager. This ought to eventually be used as a hub
for encapsulating lazily computed semantic information for syntax nodes.
For the time being, it can serve as a temporary place for mapping from
Syntax nodes to semantically full lib/AST nodes.
This is still in a molten state - don't get too close, wear appropriate
proximity suits, etc.
