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Require passing an AttrWrapper to collect_tokens_trailing_token

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This is a pure refactoring split out from #80689.
It represents the most invasive part of that PR, requiring changes in
every caller of `parse_outer_attributes`

In order to eagerly expand `#[cfg]` attributes while preserving the
original `TokenStream`, we need to know the range of tokens that
corresponds to every attribute target. This is accomplished by making
`parse_outer_attributes` return an opaque `AttrWrapper` struct. An
`AttrWrapper` must be converted to a plain `AttrVec` by passing it to
`collect_tokens_trailing_token`. This makes it difficult to accidentally
construct an AST node with attributes without calling `collect_tokens_trailing_token`,
since AST nodes store an `AttrVec`, not an `AttrWrapper`.

As a result, we now call `collect_tokens_trailing_token` for attribute
targets which only support inert attributes, such as generic arguments
and struct fields. Currently, the constructed `LazyTokenStream` is
simply discarded. Future PRs will record the token range corresponding
to the attribute target, allowing those tokens to be removed from an
enclosing `collect_tokens_trailing_token` call if necessary.
This commit is contained in:
Aaron Hill 2021-01-22 13:28:08 -05:00
parent 7e0241c637
commit 0b411f56e1
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GPG key ID: B4087E510E98B164
9 changed files with 621 additions and 407 deletions
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15
compiler/rustc_ast/src/ast.rs
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@ -2975,3 +2975,18 @@ macro_rules! derive_has_tokens {
derive_has_tokens! {
Item, Expr, Ty, AttrItem, Visibility, Path, Block, Pat
}
macro_rules! derive_has_attrs_no_tokens {
($($ty:path),*) => { $(
impl HasTokens for $ty {
fn finalize_tokens(&mut self, _tokens: LazyTokenStream) {}
}
)* }
}
// These ast nodes only support inert attributes, so they don't
// store tokens (since nothing can observe them)
derive_has_attrs_no_tokens! {
StructField, Arm,
Field, FieldPat, Variant, Param, GenericParam
}