This does a number of things, but especially dramatically reduce the
number of allocations performed for operations involving attributes/
meta items:
- Converts ast::meta_item & ast::attribute and other associated enums
to CamelCase.
- Converts several standalone functions in syntax::attr into methods,
defined on two traits AttrMetaMethods & AttributeMethods. The former
is common to both MetaItem and Attribute since the latter is a thin
wrapper around the former.
- Deletes functions that are unnecessary due to iterators.
- Converts other standalone functions to use iterators and the generic
AttrMetaMethods rather than allocating a lot of new vectors (e.g. the
old code would have to allocate a new vector to use functions that
operated on &[meta_item] on &[attribute].)
- Moves the core algorithm of the #[cfg] matching to syntax::attr,
similar to find_inline_attr and find_linkage_metas.
This doesn't have much of an effect on the speed of #[cfg] stripping,
despite hugely reducing the number of allocations performed; presumably
most of the time is spent in the ast folder rather than doing attribute
checks.
Also fixes the Eq instance of MetaItem_ to correctly ignore spans, so
that `rustc --cfg 'foo(bar)'` now works.
d029ebfc5f