sammccall planned changes to this revision.
sammccall added a comment.
As discussed offline:
We agree on the goal of disallowing duplicate types in decl-specifier-seq, but
the grammar changes are too intrusive if a guard-based approach can work
instead.
The concern with guards on `seq` nodes is duplicate work (a tree walk at every
level).
Since ForestNodes are immutable and reasonable in number we can introduce
fairly cheap caching, e.g. of whether a decl-specifier[-seq] contains an
exclusive type definition. This is a reusable building block for guards etc, so
we should build it into the contract.
The other idea I was playing with of guarding `simple-declaration :=
decl-specifier-seq /*no declarators*/ ;` by requiring the decl-specifier-seq to
declare a type (disallow "declaration declares nothing") is inferior as a) the
code is technically legal, b) it doesn't address `std::string x;` misparsing as
`Type{std} Type{::string} Declarator{x};`.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D130150/new/
https://reviews.llvm.org/D130150
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